Fisheries

1970-71

Ecological Aspects of Selected Crustacea of Two Marsh Embayments of the Texas Coast. Fred S. Conte and Jack C. Parker. June 1971. 184 pages. $3. TAMU-SG-71-211. NTIS-COM-71-00963.

Research reported here was aimed at sampling and identifying the assemblage of Crustacea collected in two highly saline marsh embayments near West Bay, Texas. Seasonal abundance of these organisms with respect to temperature and salinity were determined for the purpose of comparing seasonal variations in abundance, the coefficient of condition and the size distribution of each of the commercial penaeid shrimp, Penaeus setiferus (Linnaeus) and Penaeus aztecus Ives. The extent to which commercial shrimp use marsh bayous as nursery grounds and the effect of the pesticide malathion on commercial penaeid shrimp were also studied.

1971-72

A Hydrophonic Study of the Feeding Activities of Western Atlantic Parrotfishes. John D. Sartori and Thomas J. Bright. 92 pages. $3. TAMU-SG-72-203. NTIS-COM -73-10073.

A passive acoustic technique for monitoring feeding activities is described. A relationship between amount of calcareous material removed from a coral substrate and number of feeding sounds heard was derived, whereby it was calculated that 1050 kg/ha/yr of calcareous material would be removed by grazing parrotfishes in the study area.

1972-73

Artificial Reefs for Texas. December 1973. 39 pages. $3. TAMU-SG-73-214. NTIS-COM-74-10853/AS.

This report discusses some of the criteria that must be considered in the development of artificial saltwater reefs for the Texas coast. Materials of past and future reefs, site locations that reduce risks and enhance usability, project financing and possible alternatives and legal institutional issues are examined.

1975-76

Aspects of the Life History of the Atlantic Croaker, Micropogon undulatus. Michael L. White and Mark E. Chittenden, Jr. March 1976. 54 pages. $2. TAMU-SG-76-205. NTIS-PB-256-105/AS.

A validated scale method of age determination is described for the Atlantic croaker, Micropogon undulatus. Two age classes were generally observed, but only one was abundant. Mean total lengths were 155-165 mm at age 1 and 270-289 mm at age 11 based on three methods of growth estimation. Fish matured near the end of their first year of life when they were about 140-170 mm in total length. Spawning occurred September through March and reached a peak in October. Contrasts are presented to illustrate differences in the life histories of croaker found north and south of Cape Hatteras, N.C.

Composition of the Ichythofauna Inhabiting the 110-M Bathymetric Contour of the Gulf of Mexico, Mississippi River to the Rio Grande. Mark E. Chittenden, Jr. and Donald Moore. July 1976. 15 pages. $1. TAMU-SG-76-210. NTIS-PB-259-595.

This paper documents the ichthyofauna of the 110-m bathymetric contour of the northern Gulf from the Mississippi River to the Rio Grande. Sixty-nine species were identified. Analyses presented are based on trawl surveys conducted 1962-1964 by the Bureau of Commercial Fisheries. Implications of the present findings are discussed in Chittenden and McEachran (TAMU-SG-76-208) which reviews the demersal fish communities on the continental shelf for the entire Gulf.

1976-77

Stop Shrimp "Black Spot". Ranzell Nickelson, II and Bruce Cox. April 1977. 4 pages. TAMU-SG-77-504.

Black spot, its occurrence and its prevention are discussed in this advisory bulletin. The use of sodium bisulfite in the prevention of black spot formation, both as a powder sprinkled on layers of harvested shrimp and in solution as a dip, is explored. It was determined that the dip, in the proportions given, was far more effective due to more even distribution. Frequent changes of the dip solution ensure maximum effectiveness. The use of sodium bisulfate as related to shrimp packers and processors, as well as to consumers, is also discussed.

1977-78

Proceedings of the Second Annual Tropical and Subtropical Fisheries Technological Conference of the Americas. Ranzell Nickelson, II (comp.) October 1977. 338 pages. $10. TAMU-SG-78-101. NTIS-PB-279-405.

The conference was held April 17-20, 1977 in Biloxi, Mississippi. Twenty-eight papers were given on topics related to production, processing, packaging, distribution or utilization of tropical and subtropical fish species.

1978-79

Proceedings of the Third Tropical and Subtropical Fisheries Technological Conference of the Americas. September 1978. 365 pages. $10. TAMU-SG-79-101. NTIS-PB-289-998.

Thirty-three papers presented at the Annual Conference of the Tropical and Subtropical Fisheries Technological Society of the Americas in New Orleans, April 23-26, 1978, appear in this proceedings. Topics include utilization, production and processing of fishery products.

1980-81

Immunoenzyme Microscopy for Differentiating Among Systemic Bacteria Pathogens of Fish. D.H. Lewis. In Canadian Journal of Fisheries and Aquatic Sciences 38: 463-466 (1981). TAMU-SG-81-819.

Immunoenzyme techniques were developed for detecting subclinical infections of Yersinia ruckeri and differentiating acute yersiniosis from motile Aeromonas septicemia in channel catfish Ictalurus punctatus. Immunoenzyme techniques were comparable to immunofluorescence and cultural procedures for detecting and differentiating Y. ruckeri and Aeromonas hydrophilia infections in catfish. The availability of immunoenzyme microscopic techniques extends immunostaining microscopy to laboratories possessing only conventional microscopes.

1981-82

Proceedings of the Sixth Annual Tropical and Subtropical Fisheries Technological Conference of the Americas. Ranzell Nickelson, II (comp.). December 1981. 219 pages. $10. TAMU-SG-82-101.

The sixth annual meeting of the Tropical and Subtropical Fisheries Technological Society of the Americas was held in San Antonio, Texas, in April, 1981. This proceedings includes 21 papers which focus on factors associated with the harvesting and utilization of tropical and subtropical fishery species. Topics range from the status of the fishing industry and seafood technology in Asia, Central America and South American to reviews of the crawfish and alligator meat industries in the southern United States. Graphs, tables and photographs accompany many of the papers.

Description of Eggs and Larvae of Laboratory Reared Red Drum, Sciaenops ocellata. J. Holt, A.G. Johnson, C.R. Arnold, W.A. Fable, Jr. and T.D. Williams. In Copeia, 1981(4): 751-756. TAMU-SG-82-816.

Egg and early larval development and pigment patterns of the red drum Sciaenops ocellata are described to 13 days after hatching. The pelagic, spherical eggs had a mean diameter of 9.5 mm and usually contained one oil globule averaging 0.30 mm in diameter; about 25 percent contained two to six oil globules that coalesced into a single globule by 13 h. Hatching (at 22-23°C) occurred about 28-29 h after fertilization. Standard length at hatching was between 1.71 and 1.79 mm. Yolk-sac larvae were negatively buoyant and drifted downward (head first) about 95 percent of the time. Larvae began swimming in a horizontal position in pursuit of prey when the yolk sac exhausted and the mouth and eyes were developed. Development was temperature-dependent. Length of the yolk-sac stage varied from 40 h at 30°C to 84 h at 20°C. Growth of larval red drum was rapid after they began to feed. Larvae grew from 1.74 mm mean SL at hatching to 5.11 mean SL at 300 h. Larvae were fed rotifers Brachionis plicatilis and Artemia salina nauplii.

Differences in Hemoglobin Phenotypes among Spanish Mackerel, Scomberomorus maculatus. L.C. Skow and M.E. Chittenden, Jr. In Northeast Gulf Science, 5: 67-70 (1982). TAMU-SG-82-817.

Hemoglobin from Spanish mackerel can be fractionated into two electrophoretic patterns. Analysis of the frequencies of the two hemoglobin phenotypes suggests that Spanish mackerel from the northwestern Gulf of Mexico and from the East Coast constitute separate populations.

Reproduction, Movements and Population Dynamics of the Sand Seatrout, Cynoscion arenarius. Philip A. Shlossman and Mark E. Chittenden, Jr. In Fishery Bulletin 79(4): 649-669 (1981). TAMU-SG-82-820.

Cynoscion arenarius females mature at 140-180 mm total length (TL) as they approach age I. Spawning occurs from early March through September, with peaks in spring (March-May) and late summer (August-September). Spawning occurs in the inshore Gulf of Mexico, coinciding with the periodicity of shoreward winds and surface currents that probably transport eggs or larvae to estuarine and inshore nurseries, which are usually in water shallower than 18 m. Both spawned groups winter in the Gulf of Mexico. TL averages 210-280 mm. The largest trawled specimen was 342 mm TL, and 99.5% were less than 280 mm TL. No more than three spawned groups or two year classes occurred at any one time. The typical maximum lifespan is one to two years based on trawl data, and possibly as much as two to three years based on other collection methods. Total annual mortality rate was 99.79% based on trawl data and no less than 80-90% if maximum lifespan typically is as long as three years. Regressions of TL with total weight, girth and standard length are presented.

The Imprinting Hypothesis and Sea Turtle Reproduction. David W. Owens, Mark A. Grassman and John R. Hendrickson. In Herpetologica 38(1): 124-135 (1982). TAMU-SG-82-822.

Carr proposed that sea turtles learn characteristic components of their natal beach early in life and use olfaction and possibly other senses to locate their natal beach for nesting. Several aspects of sea turtle life history have hampered verification of this hypothesis using experiments designed to artificially imprint turtles to a new beach. Laboratory tests suggest that loggerheads Caretta caretta acquire a food preference that has an olfactory component but that food imprinting does not occur because the turtle rapidly loses this initial food preference. A preliminary laboratory attempt at artificially imprinting on chemical cues is equivocal. An alternate hypothesis is the "social facilitation model" proposed by Hendrickson, which supposes sociality for maturing turtles in which first-time nesters encounter and follow experienced adults to the nesting beach, which they then "learn" by olfactory and other navigation systems. The latter model appears to have parsimonious attributes, thus warranting increased consideration for at least some populations.

Dynamic Modeling of the Eastern Gulf of Mexico Shrimp Fishery. Vito J. Blomo, John P. Nichols, Wade L. Griffin and William E. Grant. In American Journal of Agricultural Economics 64: 475-482 (1982). TAMU-SG-82-825.

Using simulation techniques, the authors analyze the impacts of alternate management schemes on the shrimp fishery of the eastern Gulf of Mexico and compare them to a baseline. Modeling of the fishery's biological and economic functions includes intraseasonal shrimp growth rates, differences in demand for shrimp by size, and a heterogenous fishing fleet. Using consumer and producer surplus techniques, the comparisons suggest that new fishing regulations appear socially optimal. A rent-maximization scheme increases social surplus to its highest level. However, applying such a scheme to only one part of the Gulf shrimp fishery is not recommended.

1982-83

Proceedings of the Eighth Annual Tropical and Subtropical Fisheries Conference of the Americas. Ranzell Nickelson II (comp.). August 1983. 269 pages, figures and tables. $10. TAMU-SG-83-112. NTIS-PB-84-104-488.

The proceedings includes 25 papers presented at the conference. Topics include fisheries production and management, fish community ecology, fishing gear and methods, parasitology, pathology and microbiology and seafood technology.

Saltwater Fishes of Texas: A Dichotomous Key. Edward O. Murdy. August 1983. 220 pages, spiral bound, 500 + drawings. $10. TAMU-SG-83-607. NTIS-PB-83-256-842.

In the 10 years since the second edition of Key to the Estuarine and Marine Fishes of Texas was published, many studies have improved our knowledge of Texas marine fishes. Notable among these works are Bright and Cashman (1974), Hoese and Moore (1976) and the FAO Species Identification Sheets for the Western Central Atlantic (1978). These publications and other sources have provided the impetus and new information for Saltwater Fishes of Texas. The new key retains the format and style of the earlier key, but roughly 50 percent of the keys have been updated at the ordinal, familial and species levels. Saltwater Fishes of Texas includes 130 species not found in the earlier volume and contains more than 500 drawings of fishes and diagnostic structures referred to in the keys.

Contracting Problems and Regulation: The Case of the Fishery. Ronald N. Johnson and Gary D. Libecap. In American Economy Review 72(5): 1005-1022 (1982). TAMU-SG-83-809.

The paper examines common property conditions of the Texas bay shrimp fishery and other fisheries. It analyzes the limited nature of private territorial rights, customs and formal state regulation. The study argues that the heterogeneity of fishermen, a result of different skills, labor/leisure decisions and capital endowments, increases the costs of bargaining within fishing groups for controls on fishing effort and affects the types of regulations that ultimately emerge. The study demonstrates that fishermen, in general, support regulations increasing total yields without disrupting status quo rankings of fishermen, such as season closures and gear restrictions protecting juvenile shrimp. An analytical model is presented, illustrating hazards to fishermen of quota arrangements and limited entry with transferable licenses. These arrangements can redistribute income and reduce total rents in the fishery, and they explain the lack of support among shrimpers for intense regulation. The incentive of shrimpers to agree to internal effort constraints, however, increases as the fishery becomes economically overfished. At that point, detailed limited entry and quota schemes may be adopted. The paper reveals the importance of widespread support of regulations reducing enforcement costs and increasing the probability of success. While better, more productive fishermen may be few in number, their endorsement of any regulatory effort is crucial, given the high esteem they hold in fishing communities.

Development and Extinction of Food Preferences in the Loggerhead Sea Turtle, Caretta caretta. Mark A. Grassman and David W. Owens. In Copeia (4): 965-969 (1982). TAMU-SG-83-810.

Hatchling loggerhead sea turtles developed preferences for the first foods they ate after hatching. These preferences did not persist after the animals had eaten foods different from their initial diets. Thus, our results do not support the food-imprinting hypothesis in turtles. Because sea turtles fed a particular diet readily adapt to a new diet under laboratory conditions, we suggest that headstarted turtles could adapt to natural foods encountered in the wild. Finally, because the turtles chose their initially preferred diets whether or not the foods were visually disguised, chemoreception appeared significant in the turtle's food-choice behavior.

Effects of Temperature and Salinity on Egg Hatching and Larval Survival of Red Drum, Sciaenops ocellata. Joan Holt, Robert Godbout and C.R. Arnold. In Fisheries Bulletin 79(3): 569-573 (1981). TAMU-SG-83-811.

Eggs were obtained from laboratory spawnings induced by manipulations of temperature and photoperiod simulating natural seasonal changes. Brood-tank temperatures ranged from 24 to 26°C and salinities from 26 to 32 ppt. The best conditions for hatching and 24-hour larval survival were 30 ppt and 25°C. Poorest survival was at 15 ppt and 30°C. Temperature was associated with significant differences in survival of two-week-old larvae. The lowest temperature used (20°C) resulted in reduced survival rate. The effect of temperature on larval growth rate was pronounced. Growth at 20°C was much slower than at 25 or 30°C. Salinity had little influence on growth.

Spawning, Age Determination, Longevity and Mortality of the Silver Seatrout, Cynoscion nothus, in the Gulf of Mexico. Douglas A. DeVries and Mark E. Chittenden, Jr. In Fisheries Bulletin 80(3): 487-500 (1982). TAMU-SG-83-812.

Cynoscion nothus females from the Gulf of Mexico off Texas matured at 140-170 mm SL as they approached age I. Spawning occurred from early May through late October but primarily in two periods, May and August-September. Greatest spawning occurred in the August-September period when two distinct spawned groups (intrayear class cohorts) were produced. The multiple-spawned group structure within a year class may be important to the population dynamics and stability of C. nothus. This species reached 130-190 mm SL at age I. Only one year class occurred or dominated in any one month, and only two year classes were ever present at once. The largest specimen captured was 190 mm SL and 99% were <160 mm. The maximum life span (tL) was only 1-1.5 years off Texas but might be 2 years in the northcentral Gulf. The total annual mortality rate was best estimated at 99.83% and probably is no lower than 90% if the life span is as long as 2 years. Larger C. nothus almost disappeared during winter suggesting an offshore movement for overwintering.

Reproduction, Movements and Population Dynamics of the Longspine Porgy, Stenotomus caprinus. Paul Geoghegan and Mark E. Chittenden, Jr. In Fisheries Bulletin 80(3): 523-540 (1982). TAMU-SG-83-813.

Stenotomus caprinus mature at 90-125 mm TL as they approach age I. Spawning occurs once a year in a discrete period of 50-80 days from January through April, peaking in February or March. The male/female ratio was 1-to 1.21 during spawning. Spawning occurs in waters deeper than 17 m, coinciding with the periodicity of onshore surface currents in the northern Gulf of Mexico. These currents probably carry eggs and larvae inshore to nursery areas less than 27 m deep where recruitment occurs. As they mature, young-of-the-year gradually disperse to waters of 36-55 m, where age I and II fish are most abundant. S. caprinus are most vulnerable to trawling at night. Growth in length is fastest in the first eight months but slows greatly as they mature and divert energy toward reproduction. TL averaged 110-135 mm at age I, 130-155 mm at age II, and 160 mm at age III. Maximum TL is about 200 mm , and maximum lifespan is 2.5-3 years. Total annual mortality rate is 83-99%, but postspawning survival, mortality rate and lifespan vary greatly with year class. Total weight/TL, length/width, and girth/TL relationships are presented. The population dynamics of S. caprinus appears quite different from that of S. chrysops, and the genus may show zoogeographic change at Cape Hatteras, N.C.

Changes in LH and Progesterone Associated with the Nesting Cycle and Ovulation in the Olive Ridley Sea Turtle, Lepidochelys olivacea. Paul Licht, David W. Owens, Kim Cliffton and Cuauhtemoc Penaflores. In General Comparative Endocrinology 48: 247-253 (1982). TAMU-SG-83-815.

Studies of a large nesting population of the olive ridley sea turtle on the Pacific coast of Mexico established that ovulation is completed in most animals within a few days after nesting in this multiclutched species. By three days postoviposition, eggs in the oviduct contain thin, partially calcified shells, even though eggs may not be laid for as long as a month. Analysis of serum samples demonstrated the presence of a pronounced "ovulatory surge" in luteinizing hormone (LH) and progesterone (Pro). Levels of both hormones increase by more than an order of magnitude within a day after oviposition and return to near baseline levels within 2 to 3 days, by the time the egg shell membrane appears. Testosterone and estradiol levels change little in the preovulatory period. These increases in LH and Pro are highly correlated in both time and magnitude. Increases in Pro comparable to the ovulatory surge could not be induced by injection of extracts of homologous pituitaries into preovulatory animals before nesting. Also, gonadotropin releasing hormone and a potent agonistic analog were inactive in both sexes of the breeding turtle.

Growth of Juvenile Red Snapper, Lutjanus campechanus, in the Northwestern Gulf of Mexico. Scott A. Holt and Connie R. Arnold. In Fisheries Bulletin 80(3): 644-648 (1982). TAMU-SG-83-816.

Red snapper were collected off Texas from an artificial reef (sunken liberty ships) with fish traps, and from the outer continental shelf by trawling. The largest fish trapped were 100-110 mm, and the smallest trawled were 20-29 mm. Bimodal size distributions indicate that juvenile red snapper grow more slowly than previously reported. Data indicate the fish grow to 110-130 mm the first year and 200-230 mm the second year. The distinct bimodality in length frequencies in snapper less than 220 mm from June through December indicated the presence of two year classes within this size range. Tagging studies indicated that snapper stay around the artificial reef during the summer and fall, but none were captured there or elsewhere after December.

The Commercial Production of Mudminnows (Fundulus grandis) for Live Bait: A Preliminary Economic Analysis. Benita P. Waas, Kirk Strawn, Michael Johns and Wade Griffin. In Texas Journal of Science XXXV(1): 51-60 (1983). TAMU-SG-83-820.

The economic feasibility of operating a commercial mudminnow farm was determined using the Generalized Budget Simulation Model for Aquaculture developed at Texas A&M University. A ten year planning horizon was used. Initial investment costs, annual budgets and cash flows were estimated to determine cost, returns and profit. Economic profit, break-even analysis and net present value were used to evaluate the economic feasibility. Based on a grow-out stocking density of 400,000/ha, 85 percent projected survival, two crops per year and achieved production at 80 percent of capacity, the 24-ha facility showed an economic profit of $41,160 for the sixth year of operation. The break-even price of $0.40/dozen was $0.25 less than the market price of $0.65. The break-even production of 278,705 dozen/year is 174,629 dozen less than the assumed annual production of 453,334 dozen.

1983-84

Western Gulf of Mexico Sea Turtle Workshop Proceedings. David Owens, et al. October 1983. 74 pages, 3 tables, 1 photograph. $3. TAMU-SG-84-105. NTIS-PB-84-121-177.

This publication summarizes the presentations made at the Western Gulf of Mexico Sea Turtle Workshop, held January 13-14, 1983 at Texas A&M University. The following presentations were made: "Current Status of the Kemp's Ridley Population", "Historical Background of the International Conservation Program for Kemp's Ridley", "Padre Island Hatchery Research", "Headstarting Kemp's Ridley", "Experimental Marking of Sea Turtles by Tissue Modification", "Random Notes on Sea Turtles in the Western Gulf of Mexico", "Sea Turtle Stranding and Salvaging Research", "Turtle Excluder Device" and "Oil and Gas Impacts on Marine Turtles in the Gulf of Mexico."

Cutting Fuel Costs: Alternatives for Commercial Fishermen. Dewayne Hollin and Steven Windh. January 1984. 17 pages, 2 charts, 2 graphs, 9 illustrations. TAMU-SG-84-504.

If you're looking for ways to reduce fuel consumption or increase fuel efficiency, this publication is a place to start. It describes 14 alternatives for commercial fishermen, including long-term maintenance measures and long-term alternatives such as management aids, devices to improve engine performance and vessel modifications. Advantages and disadvantages of each alternative are listed along with cost and economic data estimates. Although costs vary with time and geographic location, the estimates can help you decide which alternatives you might want to investigate more thoroughly. Alternatives described include speed reduction, hull maintenance, self-polishing paints, fuel flow meters, track plotters, LORAN C equipment, turbochargers, engine changeout, diesel fuel preheaters, controllable pitch propellers and bulbous bows. A payback formula worksheet and example are included to help you calculate how long it would take for any particular device or modification to save enough fuel to pay for itself.

Seasonal Occurrence of Black Drum, Pogonias cromis, and Red Drum, Sciaenops ocellatus, off Texas. Jeffrey L. Ross, John S. Pavela and Mark E. Chittenden, Jr. 1983. In Northeast Gulf Science 6(1): 67-70. TAMU-SG-84-802.

The black drum, Pogonias cromis, and red drum, Sciaenops ocellatus, are important recreational and commercial fishes commonly captured on the Atlantic coast of the United States from Virginia to Key West, Florida and along the Gulf of Mexico (Gulf) to at least northern Mexico. The literature describes various aspects of the life history of both species, but their winter distribution has not been well defined. This paper provides data on the seasonal occurrence and distribution of black drum and red drum off Texas.

Texas Shrimpers: Community, Capitalism and the Sea. Robert Lee Maril. September 1984. 222 pages. $18 (plus shipping and applicable sales taxes). TAMU-SG-84-805. Order from Texas A&M University Press, Texas A&M University, College Station, Texas 77843.

In preparing management plans for the shrimp fishery of the Gulf of Mexico, the Gulf of Mexico Fisheries Management Council is instructed to consider socioeconomic data as well as that related to fisheries biology. Until this book was published, however, the social and economic situation of Texas shrimpers had not been documented. The book describes the work and life of a shrimper and tabulates information obtained in interviews with shrimpers, such as incomes, families, age, ethnicity, work attitudes, costs and returns for vessels, and landings.

1984-85

Proceedings of the Ninth Annual Tropical and Subtropical Fisheries Conference of the Americas. Ranzell Nickelson, II (comp.). November 1984. 344 pages, numerous figures and tables. $12. TAMU-SG-85-106. NTIS-PB-85-221141/AS.

This proceedings includes 21 papers presented at the conference. Topics include fisheries production and management, seafood technology, pathology and microbiology, parasitology and seafood marketing.

Aspects of Reproduction, Larval Development, and Morphometrics in the Pyramidellid Boonea impressa (Odostomia impressa) (Gastroposa: Opistobranchia). Marie E. White, Christopher L. Kitting and Eric N. Powell. In The Veliger 28(1): 37-51 (1985). TAMU-SG-85-823.

Boonea impressa is an important ectoparasite of the American oyster, Crassostrea virginica. Here, the reproductive and larva life history, intraspecific variation in certain shell characters, and the internal anatomy of the feeding apparatus are described for population of B. impressa from the western Gulf of Mexico (Texas) and, for the latter two subjects, the western Atlantic (North Carolina). Larval development in the Pyramidellidae is reviewed. The life-span of B. impressa was approximately one year. Reproduction occurred throughout the year, but peaked in mid-summer. Eggs (182-238 um diameter) were deposited in numbers of 20-250 per egg mass. Larval development from oviposition to be hatched veliger required 3.3-4.8 days. Two days after hatching, the veligers became negatively phototaxic. Metamorphosis occurred within one week of hatching. The developmental mode of B. impressa fits that designated as Type II-lecithotrophic, and agrees with that expected for an opistobranch with a stable food source. The short pelagic life-span may facilitate dispersal for a species with a non-mobile, but patchy host. Recently metamorphosed B. impressa often attached near the aperture of an adult. This behavior may protect the young snail from predation and increase access to its food supply. The internal anatomy of the feeding apparatus differed from European odostomians in the absence of a well developed first buccal pump. Shell sculpture (number of cords per whorl) was most dependent on the length of the whorl. Adult snail size, whorl length, whorl width, and the number of spiral cords varied significantly between populations collected from Texas and North Carolina. Egg size, size of the components of the feeding apparatus, whorl length-width ratio, and protoconch size differed less. These latter characters might be employed advantageously in the study of interspecific differences among odostomians where, heretofore, characters with greater intraspecific variability typically were used.

1985-86

Proceedings of the Tenth Annual Tropical and Subtropical Fisheries Conference of the Americas. D.R. Ward and G.D. Treece, (comps.). November 1985. 313 pages. $15. TAMU-SG-86-102. NTIS-PB-86-140-688/AS.

The 10th annual meeting of the Tropical and Subtropical Fisheries Technological Society of the Americas was held in New Orleans, Louisiana, in January 1985. This proceedings includes 26 papers which focus on economics, fisheries production and management, seafood processing, pathology and microbiology, and seafood technology. This volume also includes an author and subject index for Volumes 1 through 10. Volumes 2 through 9 are still available through the Texas A&M University Sea Grant College Program.

Proceedings of the Shrimp Yield Prediction Workshop. André M. Landry, Jr., and Edward F. Klima, editors. $10. TAMU-SG-86-110.

Shrimp stocks of the Gulf of Mexico represent an extremely valuable commodity whose management falls under the jurisidiction of state and federal fisheries agencies. The Shrimp Yield Prediction Workshop traced the evolution of state and federal programs designed to manage shrimp resources. Management strategies and goals of various regulatory agencies' shrimp research programs were discussed. Insight was gained into the significance of abundance and size data obtained by traditional sampling methods, correlations of life history trends and hydrological factors, census data gathered from the bait-shrimp fishery and density information acquired from new quantitative techniques as predictive tools for shrimp resource management. The workshop also assessed the state of the art of predicting shrimp yield and identified critical problems in rendering meaningful predictions.

Economics of Harvesting and Market Potential for the Texas Blue Crab Industry. Charlotte L. Miller and John P. Nichols. September 1985. 118 pages, 24 tables, 18 figures. $5. TAMU-SG-86-201.

Texas ranks third in blue crab production within the Gulf of Mexico region. Two occurences which have directly affected the Texas blue crab industry began in 1975, an increase in involvement of Northeastern interest in the processing industry and an influx of Indochinese pickers and crabbers. These developments resulted in increased production due to more efficient harvesting and processing and an increase in the export of whole crabs and crabmeat to East coast markets. This report describes the Texas blue crab industry and identifies market development opportunities within Texas and the surrounding regions. The typical crab consumer is described as a middle-aged, white collar worker in the middle-income range. Demographic projections indicate that this socioeconomic group will increase, resulting in a growing market for crab. If a larger regional market should develop, according to the authors, prices rise and greater interest develops in commercial harvest, the resource may come under greater pressure. This suggests that greater emphasis be placed on more refined public management, including licensing of commerical crabbers.

Effects of Seismic Sounds on Marine Organisms: An Annotated Bibliography and Literature Review. T.L. Linton, N. Hall, D. LaBomascus and A.M. Landry. October 1985. 67 pages, 10 figures, 2 tables, 5 appendices. $3. TAMU-SG-86-604. NTIS-PB-86-13-598/AS.

Techniques of geophysical exploration are constantly changing, spurred by concerns for speed, efficiency and environmental protection. This project collects and reviews published studies relating to the effects of devices used for sound wave generation in geophysical exploration upon important marine organisms of the Texas coastal waters, including bays and estuaries. Researchers report that high-velocity explosives burn rapidly and produce a very fast buildup in pressure which kills fishes. The degree of lethality is directly related to charge size and distance from detonation site. Low-velocity explosives generate a moderate pressure buildup and relatively low peak pressure, producing relatively no lethal effects to aquatic organisms. Non-explosive sound sources such as air guns have a moderate pressure rise-time similar to that produces by low-velocity explosives. Although few studies have been conducted with air guns, they appear to have little adverse effect upon aquatic organisms.

Benthos Structure and Function in a South Texas Estuary. Flint. Contributions in Marine Science (1985) Vol. 28: 33-5. TAMU-SG-86-801.

The Corpus Christi Bay estuary in the northwestern Gulf of Mexico was investigated for spatial and temporal variation of benthos community structure and function. Four stations were sampled quarterly for 2.5 years to investigate for macroinfaunal species assemblage changes as well as changes in benthic metabolism and nutrient regeneration. Cluster analysis of species assemblages illustrated that community structure changed from the riverine-influenced end of the estuary to the oceanic-influenced end. Taxa number increased away from the fluvial source while total abundance decreased. Maximum biomass was observed in the middle estuary region. Although spatial patterns were evident, no consistent seasonal patterns were observed for community structure characteristics from one site to the next. Community functional processes were not significantly different between sites. Metabolism did not show consistent temporal patterns but sediment nutrient flux always exhibited peak rates during the summer at all sites. Sediment texture differences as well as variability in salinity between sites were thought to influence benthos structure and function in this estuary. Multivariate discriminant analysis differentiated communities according to 1) those that inhabited a less variable environment (salinity) and supported more benthic taxa, and 2) those that inhabited a significantly different kind of sediment, supported fewer taxa, and exhibited much greater faunal biomass with corresponding larger metabolic rates. A comparison with other estuaries indicated that Corpus Christi Bay benthic metabolic rates were intermediate and that nutrient regeneration rates were high in those estuaries where similar data were available.

Pineal Gland and Melanton in Sea Turtles. Owens and Gern. Current Trends in Comparative Endocrinology (1985). pp. 645-648. TAMU-SG-86-805.

Sea turtles possess unusually large pineal complexes which are highly vascularized and glandular in appearance. Histologically, secretory rudimentary photoreceptors and neurological supportive cells are distinguishable. However, there is no evidence of pineal innervation or typical photoreceptors in immature specimens of either the green (Chelonia mydas) or the loggerhead (Caretta caretta) sea turtles. Ralph has hypothesized a positive correlation between pineal complex development (importance?) and increasing latitude. This relationship has been supported in lizards and certain rodents. Sea turtles, which are primarily tropical and subtropical, do not fit this pattern. Using a melatonin radioimmunoassay, we have conducted several physiological experiments to try to determine the role of the pineal gland and melatonin in these species. Even though at one time it was thought that melatonin might be a unique pineal product, it is now clear that this indoleamide occurs in several other tissues including the retina where it is probably synthesized. Melatonin has also been found in the blood of pinealectomized rats, sheep and rainbow trout. In the course of two experiments in which pinealectomy was performed on C. mydas, we have been able to examine melatonin titers post-operatively.

Comparative Endocrinology of Sea Turtles. Owens and Morris. Copeia, 1985 (3), pp. 723-735. TAMU-SG-86-807.

In recent years, an effort has been made to begin to understand the endocrine regulation systems of endangered sea turtles. The purpose of the present paper is to review this area. The glycoproteins follicle stimulating hormone (FSH), luteinizing hormone (LH), and the thyroid stimulating hormone (TSH) have been purified from pituitaries of Chelonia mydas. A homologous radioimmunoassay for LH has been used to document a clear relationship between LH, ovulation and a pronounced progesterone peak which occurs as albumin is being secreted in the oviduct. A distinct role for FSH has yet to be proven, although, because estrogens seem to be out of phase with LH and progersteone, FSH may regulate estrogen. A complication with this suggestion, however, is that the reptiles which have been studied seem unique among tetrapods in not having LH and FSH receptor specificity. Circulating estrogens are at very low titers (20-50 pg/ml), with peaks in spring that may correlate with migration and ovarian maturation as well as during the internesting interval when subsequent follicular size classes are maturing. Testosterone is elevated slightly in female C. mydas during mating receptivity, but is much lower than early spring samples from mating males. The two species in the genus Lepidochelys hold mature eggs in their oviducts, apparently to ensure adequate recruitment of nesters for their unique mass nesting (arribada) system. Environmental temperature appears to directly affect some sea turtle endocrine systems. The unusually elaborate pineal complex in marine turtles produces the hormone melatonin which is reduced in the circulation and cerebrospinal fluid by the animal's exposure to light. Temperature, photoperiod and nutritional history appear capable of regulating reproductive cycling in these multiannual nesters. Much less is now known about males than females. Growth hormone (GH) and to a lesser degree prolactin are somatotrophic in marine turtles. GH also appears to synergize with gonadotropin in inducing final testicular spermiation. TSH from sea turtles or mammals did not stimulate the sea turtle thyroid in two separate assays, an observation which is both unexpected and unexplained. The ACTH-interrenal-stress axis in sea turtles is similar to other vertebrates with the glucocorticoid corticosterone demonstrating peaks at hatching, entry into the ocean and during induced stress situations.

Diel Periodicity of Spawning in Sciaenids. C.R.Arnold, S.A. Holt, G.J. Holt. Marine Ecology - Progress Series. Vol. 27: 1-7, 1985. TAMU-SG-86-812.

Time of day was determined for spawning of several species of sciaenid fishes by examining development stages of eggs collected in estuarine and near-shore plankton samples. Estuarine samples were taken at different times of day and night but newly spawned Cynoscion nebulosus and Bairdiella chrysoura eggs were taken only during a period from just before to 3 or 4 hours after sunset. Sciaenops ocellatus and Mentichirrhus sp. eggs from near-shore Gulf of Mexico samples, taken during the morning, all contained tail-bud stage embryos, indicating evening spawning in these species. It is proposed that evening spawning reduces predation on sciaenid eggs by allowing dispersal of eggs during the night when planktivores may be less active. Overnight dispersal reduced C. nebulosus egg density from 100 m-3 during evening spawning to 1 m-3 the next afternoon. Lower egg densities during the day would reduce egg mortality due to predation. Egg predation experiments showed that predation rates increased with increasing egg density but no difference was found in predation rates between trials run in light and total darkness.

Effects upon Selected Marine Organisms of Explosive used for Sound Production in Geophysical Exploration. T.L. Linton, A.M. Landry, J.E. Buckner and R.L. Berry. The Texas Journal of Science, XXXVII (4):pp. 341-353 (1985). TAMU-SG-86-832.

Survival rate and extent and nature of injury were monitored for red drum (Sciaenops ocellatus), black drum (Pogonias cromis), blue crab (Callinectes sapidus), white shrimp (Penaeus setiferus), and American oyster (Crassostrea virginica) held in cages at logarithmic distances (one to 46 meters) from where a strand of commercially available explosive (Primacord with 100 grams of powder per 33 centimeters), commonly used to produce sound waves for seismic exploration, was detonated in a shallow water environment. Survival of test organisms varied with species, depth of cage, and distance from detonation site. Fish held at the surface exhibited low mortality, whereas those in bottom cages closest to site of detonation (one and 23 meters away) exhibited mortality rates between 40 and 100 percent. The swimbladder, kidney, and peritoneum were all most frequently damaged organs in fish. Shrimp exhibited modest mortality rates at all stations and water depths. Survival of shrimp did not appear to be related to distance from detonation. Blue crab survival appeared to be directly related to distance from detonation site. Survival of oysters was high at all stations and inversely proportional to distance from sound source. Varying results among test organisms were attributed to pressure wave characteristics associated with charge detonation. Comparable testing is needed during summer months to determine effects under "worst case" conditions when greater numbers and life stages of organisms are present and ambient conditions more stressful in these shallow water environments.

Biological Enhancement of Estuarine Benthic Community Structure. Flint and Kaike. Marine Ecology - Progress Series, Vol. 31: 23-33, 1986. TAMU-SG-86-833.

Benthos in south Texas estuaries are normally concentrated in the top 3 to 4 cm where the sediment is well-oxygenated and less compact. Where larger infauna such as enteropneusts, ophiuroids, or echiurans occur in the sediments bioturbation by these infauna oxygenates and redistributes normally uninhabitated deeper sediments. A natural disturbance to Corpus Christi Bay benthos by these larger infauna could increase density and expansion of infaunal populations into deeper regions of the sediments, as well as enhance colonization by new infaunal species. During a 3.5 yr study of infaunal benthos there was a change in community structure associated with colonization of the soft-bottom habitat by the enteropneust Schizocardium n. sp. that resulted in a species composition atypical for a middle estuary habitat. After 2 yr the enteropneust population disappeared and the diverse and productive soft-bottom community regressed to pre-enteropneust characteristics. Increased aerobic sediments during enteropneust presence may have diminished predicted competition and encouraged development of a more diverse community than would have otherwise existed.

Niche Characterization of Dominant Estuarine Benthic Species. Flint and Kaike. Estuarine, Coastal & Shelf Science (1986), 22- 657-674. TAMU-SG-86-836.

Benthic macroinfaunal species in a south Texas estuarine environment were studied over a 2-5 year period to characterize their distributions and ecology. The 13 dominant taxa chosen for investigation exhibited distinct habitat usage differences as judged both by the use of discriminant analysis and the differentiation of behavioral characteristics. Species coexistence in the estuarine benthic community of Corpus Christi Bay was examined with respect to resource partitioning for such parameters as food and space. Utilization of these resources by the dominant taxa differed in both temporal and spatial dimensions, with the spatial dimension consisting of horizontal and vertical attributes. Benthic species were separated according to 1) occurrences in certain sediment types with varying organic content, 2) presence in estuarine regions characterized by different phytoplankton productivity rates, 3) different periods of annual occurrence, and 4) occurrence in different sediment microhabitats characterized by varying sediment depth and relation to depth of oxygenated sediments. Superimposed upon differences in habitat usage of these species were behavioral traits, such as feeding differences, which further discriminated how benthic species obtained resources. Based upon species occurrence in a certain characteristic environment, we speculated on the structural division of the benthic habitat by various taxa often classified as common members of the same species' assemblages in the past. Although other investigators have demonstrated interactions among co-occurring benthic infaunal species, the information presented here illustrated how these species could minimize interactions in order to maintain their populations.

1986-87

Age and Growth of Four Carcharhinid Sharks Common to the Gulf of Mexico: a Summary Paper. S. Branstetter and J.D. McEachran. Indo-Pacific Fish Biology: Proceedings of the Second International Conference on Indo-Pacific Fishes. 1986. pp. 361-371, Ichthyological Society of Japan, Tokyo. TAMU-SG-87-801.

Age and growth information is presented for four shark species: Carcharhinus limbatus, C. falciformis, Galeocerdo cuvieri, and Rhizoprionodon terraenovae. Ages were estimated from vertebral centrum ring structure. Results were verified through back calculations and marginal increments, and validated through grow-out studies on live sharks injected with a marker, tetracycline. Age at recruitment to a developing fishery is similar for all four species at 3-4 year of age, however they enter the fishery at different stages of their life histories. The species are taken in various combinations during fishing efforts, therefore fishery management at the group level is desirable, but due to differences in their life histories, may prove to be difficult.

Bay and Offshore Fishing in the Galveston Bay Area: A Comparative Study of Fishing Patterns, Fishermen Characteristics and Expenditures. Graefe and Ditton. North American Journal of Fisheries Management (1986), 6: 192-199. TAMU-SG-87-803.

Saltwater boat fishing patterns as well as fishermen characteristics and expenditures near Houston and Galveston, Texas, were investigated through a 1979 mail survey of registered boat owners who fished the Galveston Bay area. Bay and offshore fishermen were similar in most respects (income was an exception) but their economic impact varied greatly. Offshore fishing parties spent nearly twice as much money per day on the average as bay parties, but they contributed only about one-fifth as much to the regional economy because they were fewer in number and made fewer fishing trips. Offshore fishing parties were more likely than bay parties to buy snack foods and beverages, restaurant meals, tackle and equipment, and gas and oil for their boat in the coastal community. The findings presented here point to important differences in participation, spending and economic impact that need to be examined further elsewhere. The approach and findings should be of use to fishery managers and local officials when they allocate resources based on economic impact perspectives.

Utilization of Salt Marsh Plants by Postlarval Brown Shrimp: Carbon Assimilation Rates & Food Preferences. Gleason. Marine Ecology - Progress Series (1986). Vol. 31: 151-158. TAMU-SG-87-804.

Changes in stable carbon isotope ratios were monitored at 4 d intervals for postlarval Penaeus aztecus Ives reared on plant foods representative of those found within a Spartina alterniflora Loisel salt marsh. Plant materials fed to shrimp, individually and in combination, included Skeletonema costatum (Greville) Cleve, Isochrysis sp., Spartina detritus, and epiphytes that grow on Spartina. Results of carbon isotope analyses indicated that the most rapid changes in tissue d13C values occurred when shrimp were fed S. costatum alone or all foods combined. In both of these treatments the half-life of tissue carbon was reached before the first doubling of weight. Although shrimp fed epiphytes showed growth, significant assimilation of diet carbon was not detected. Food preferences were assessed with those materials which promoted growth (i.e. S. costatum and epiphytes) and, although there was no preference for S. costatum and epiphytes together compared to epiphytes alone, selection for both of these materials was greater than for S. costatum alone. Results indicate that (i) certain plants common in Spartina salt marshes such as the diatom S. costatum , can be important for metabolic maintenance in postlarval P. aztecus and (ii) postlarval brown shrimp may have substrate preferences that are not related to plant food value.

User-Resource Planning Framework for Offshore Recreational Artificial Reefs. Gordon and Ditton. Coastal Zone Management Journal, Vol. 13, No. 3/4. pp. 369-395. 1986. TAMU-SG-87-811.

Artificial reefs have been used extensively in coastal waters to attract and enhance recreational fishery resources. In the United States, they have been traditionally built from "materials of opportunity" using limited budgets. This paper explores some past planning philosophies and presents a recent artificial reef deployment case that demonstrates a lack of sensitivity to local and regional recreational demand. A systems framework is developed to guide future planning efforts in artificial reef development. The framework is intended to integrate previously fragmented knowledge and to demonstrate the interdisciplinary nature of artificial reef planning. Emphasis is given to advance planning, user dimensions, and the integral issue of reef access.

Effect of Carbon Dioxide on Growth-rates of Selected Microorganisms Isolated from Black Drum (Pogonias cromis). Michel Lannelongue and Gunnar Finne. In Journal of Food Protection 49(10): 806-810 (1986). TAMU-SG-87-831.

The effect of carbon dioxide (25-100%)-enriched atmospheres on growth rates of a coryneform bacterium, Micrococcus varians, a Vibrio sp., a Moraxella sp. and Pseudomonas fluorescens growing on trypticase soy agar at 4 and 25°C was investigated. Growth rates were determined by measuring the rate of increase in the diameter of colonies on plates packed in laminated plastic pouches containing the CO2-enriched environments. Carbon dioxide caused a significant decrease in the growth rates of all the organisms and the inhibitory effect was greatly enhanced by low temperatures. At 25°C, the gram-positive organisms were more resistant to CO2 than the gram-negative organisms, while at 4°C none of the organisms grew in 25% CO2, the lowest concentration tested. When exposed to air after being incubated in CO2-enriched environments, the organisms in most instances grew at normal rates indicating limited residual effect of CO2. The effect of temperature on relative CO2 inhibition was investigated in detail for the Moraxella sp. and P. fluorescens. In an atmosphere containing 25% CO2 in air at 20°C both organisms showed approximately 25% inhibition as compared to growth in air at the same temperature, while at 10°C P. fluorescens was completely inhibited and the Moraxella sp. showed 95% inhibition.

Chemoreception in the Homing and Orientation Behavior of Amphibians and Reptiles, with Special Reference to Sea Turtles. David Owens, Diana Crowell Comuzzie, and Mark Grassman. In Chemical Signals in Vertebrates 4. Ed. by David Duvall, Dietland Muller-Schwarze and Robert M. Silverstein. pp. 341-355. Plenum Publishing Corporation, 1986. TAMU-SG-87-832.

The importance of chemoreception in the life history of amphibians and reptiles has been reviewed on several occasions. Our task is considerably more specific as our interest is in the chemosensory components of orientation and homing. As in the far better documented avian and mammalian classes, it appears to be a gross over-simplication to think that an amphibian or reptile would rely on a single sensory system for homing or orientation. In fact a major difficulty that researchers appear to have had is the experimental dissection of the separate sensory modes in preparing protocols using the various animal models. It is very tricky to test just for chemoreception for example. Even though other senses surely must be important, we have attempted to avoid digressions into visual, tactile or other sensory systems. In actuality, evolution is acting to integrate all these systems in animals that have developed unusually keen orientation and homing abilities.

Abundance, Age Distributions and Growth of the Texas Hard Clam, Mercenaria mercenaria texana in Texas Bays. M. Alison Craig and Thomas J. Bright. In Contributions in Marine Science 29:59-72 (1986). TAMU-SG-87-840.

The hard clam Mercenaria mercenaria (Linne) has been well studied; however little information is available on Mercenaria mercenaria texana, the subspecies found in Texas bays. Age and growth of Mercenaria mercenaria texana in Christmas Bay, Texas were determined by sectioning the shell and examining annual growth bands. Christmas Bay harbors a sparse population of older clams with few under five years old. Substrate type plays an important role in the distribution and growth of the bivalve. Christmas Bay clams exhibited poorer recruitment and slower first year growth than did clams from Texas bays further south. Mercenaria mercenaria texana shows a pattern of growth similar to that reported in the literature for hybrids of Mercenaria mercenaria (Linne) and Mercenaria campechiensis (Gmelin).

1987-88

Explanation of "Red Oysters." January 1988. TAMU-SG-88-504.

Following an occurrence of red-hued oysters off the Texas coast, this fact sheet was prepared to describe the phenomena and to reinforce the public's confidence in the oyster harvest. A relatively simple test whereby packers could determine if a frozen oyster might turn red was also included.

1988-89

Proceedings of the First International Symposium on Kemp's Ridley Sea Turtle Biology, Conservation and Management. C.W. Caillouet and A.M. Landry, compilers. 260 pages. $20.00. TAMU-SG-89-105.

These proceedings contain papers and abstracts based on presentations made at the First International Symposium on Kemp's Ridley Sea Turtle Biology, Conservation and Management in Galveston, Tex., October 1985. Most papers have been updated by the respective authors to reflect 1989 data. The proceedings includes 33 papers and five abstracts, as well as transcripts of question and answer sessions and a concluding panel discussion.

1989-90

Adaptive Coloration in Invertebrates. M. Wicksten, compiler, August 1990. 144 pages. $15. TAMU-SG-90-106.

This publication is based on papers presented at an adaptive coloration symposium sponsored by the Divisions of Animal Behavior and Invertebrate Zoology of the American Society of Zoologists in 1987. The collection provides a variety of aspects of adaptive coloration in diverse taxa, with the goal of presenting summaries for review as well as stimulation for further research. Biologists tend to specialize according to taxa or disciplines, and interdisciplinary comparisons can be difficult yet rewarding. Studies on adaptive coloration among invertebrates could show important differences in protective mechanisms between and within taxa as well as between land, freshwater and marine habitats. Following an introduction by the compiler, the book includes the following papers: "The Evolution of Animal Coloration: Adaptive Aspects from Bioenergetics to Demography," Ward B. Watt; "Industrial Melanism in Moths; A Review and Reassessment," Theodore D. Sargent; "Relationships Between Visual Characteristics of Rainforest Butterflies and Responses of a Specialized Insectivouous Bird," Peng Chai; "A Kaleidoscope of Cryptic Colors: Polymorphic Caterpillars and Camouflaged Adults on a Multi-colored Host Plant," Justin O. Schmidt; "Adaptive Coloration of Pontoniine Shrimps (Crustacea: Decapoda: Caridea)," Deborah L. Zmarzly; "Aposematism and Bioluminescence in Coastal Marine Communities," Matthew S. Grober; "Analyzing Color Pattern as Complex Trait: Wing Melanization in Pierine Butterflies," Joel G. Kingsolver and Diance C. Wiernasz; "Photoprotective Pigmentation of Freshwater Zooplankton: A Phenomenon of Extreme Environments," Chris Luecke and W. John O'Brien; "Adaptive Coloration in Texas Fiddler Crabs (Uca)," Carl L. Thurman II; "Special Resemblance, Aposematic Coloration and Mimicry in Opisthobranch Gastropods," Terrence M. Gosliner and David W. Behrens.

The Effect of the Ectoparasitic Pyramidellid Snail, Boonea impressa, on the Growth and Health of Oysters, Crassostrea virginica, under Field Conditions. Elizabeth A. Wilson, Eric N. Powell and Sammy M. Ray. 1988. Fishery Bulletin 86 (3): 553-566. TAMU-SG-90-819.

Boonea (=Odostomia) impressa are contagiously distributed on oyster reefs so that some oysters are parasitized more than others. The parasite's mobility and the ability of oysters to recover from snail parasitism may be important in assessing the impact of parasitism on oyster populations. During a four-week exposure period in the field, B. impressa reduced American oyster, Crassostrea virginica, growth rate and increased the intensity of infection by the protozoan, Perkinsus (= Dermocystidium) marinus, but produced few changes in the oyster's biochemical composition because, although net productivity was reduced, the oysters retained a net positive energy balance (assimilation > respiration). During a four-week recovery period, growth rate returned to normal (control) levels, but infection by P. marinus continued to intensify in previously parasitized oysters kept B. impressa-free. Most changes in biochemical composition during recovery, including increased lipid and glycogen contents, could be attributed to the continuing increase in infection intensity of P. marinus. Consequently, the temporal stability and size of snail patches, particularly as they regulate infection by P. marinus, may be the most important factors influencing the impact of B. impressa on oyster reefs.

Control of Gonadotropin Release in the Atlantic Croaker (Micropogonias undulatus): Evidence for Lack of Dopaminergic Inhibition. Paul A. Copeland and Peter Thomas. 1989. General and Comparative Endocrinology 74: 474-483. TAMU-SG-90-823.

Gonadotropin (GTH) secretion is known to be under inhibitory dopaminergic control in several species of fish. To investigate whether this is also the case in the Atlantic croaker (Micropogonias undulatus), juvenile and adult croaker were treated with a gonadotropin-releasing hormone analog (des-Gly10 D-Ala6 Pro9 n ethylamide luteinizing hormone-releasing hormone (LHRHa), 1-100 ng/g body wt) in combination with various dopaminergic drugs (1-20 mg/kg body wt). None of the dopamine antagonists tested, metoclopramide, pimozide, haloperidol and domperidone, were able to increase plasma GTH levels above those induced by treatment with LHRHa alone and in some cases the gonadotropin response to LHRHa was reduced. The dopamine agonists bromocryptine and apomorphine either had no effect on the normal response to LHRHa or increased it. None of the drugs tested had any detectable effect on GTH levels in the absense of LHRHa. These results provide evidence for a lack of dopaminergic inhibition in the control of GTH secretion in the Atlantic croaker.

1990-91

Tidal Stream Transport of Larval Fishes into Non-stratified Estuaries. S.A. Holt, G.J. Holt, and C.R. Arnold. 1989. In Rapp. P.-v. Reun. Cons. int. Explor. Mer, 191: 100-104. TAMU-SG-91-801.

Larvae and juveniles of several fish species utilize tidal flow as a mechanism for migration. Reliance on the differences in direction of the net non-tidal flow between surface and bottom appears to be a major strategy for transport and retention of fish larvae in partially-stratified estuaries. Vertical movement by fish up into the current stream, when the flow is in the "desired" direction of travel, and movement down to the bottom, out of the current stream, when the flow is in the opposite direction (a process termed "selective tidal stream transport") facilitates the migration of juveniles and adults of several species. Tidal stream transport has been demonstrated in the larvae of only a few species and the generality of this process as the mechanism for larval transport into estuaries has not been established. Towed ichthyoplankton samples were taken on flood tide and the subsequent ebb tide at surface and bottom at five stations on a transect across the Aransas Pass tidal inlet, Texas, to test the hypothesis that larval red drum (Sciaenops ocellatus) moved to the edges and/or moved to the bottom on ebb tide and, in both cases, moved into the water column on flood tide to take advantage of the reduced currents at the boundaries. There was no evidence of horizontal movement but larval red drum did appear to move vertically in response to tidal direction. Larval red drum were more abundant on the bottom than on the surface on both flood and ebb but the difference was much greater on the ebb flow. The response to tidal direction was weak compared to dramatic differences seen in some other species. There was little difference in density of larvae between flood and ebb tide but the mean size was larger on flood than ebb, suggesting that only the larger individuals are leaving the tidal plume and being retained in the estuary.

Reproduction, Movements, and Apparent Population Dynamics of the Atlantic Threadfin Polydactylus octonemus in the Gulf of Mexico. M.W. Dentzau and M.E. Chittenden, Jr. 1990. Fishery Bulletin, U.S. 88:439-462. TAMU-SG-91-802.

Trawl collections were made for Atlantic threadfin Polydactylus octonemus from 5 to 100 m in the Gulf of Mexico along a cross-shelf transect off Texas during October 1977-August1981. Threadfin generally mature at 165-210 mm TL as they approach 7-9 months of age. Spawning primarily occurs in one period, mid-December-mid March, and spans 45-120 days overall; 90 percent of successful spawning may occur in only 59 percent of that period. Threadfin in the northwestern Gulf range from <5 to 27 m depths in the demersal stage but are most abundant at <5 to 16 m. Young-of-the-year recruit in waters <5-16 m when 2-4 months old. Fish begin to disperse to deeper waters in early summer and form a positive size gradient from the estuaries seaward. Threadfin in the demersal phase are not abundant in the northwestern Gulf after 9-11 months of age and reach only 15 months there. Observed mean and predicted sizes were 135-165 mm TL at 6 months, 165-215 mm at 9 months, and 180-205 mm at 12 months. Fitted von Bertalanffy parameters were 2.17-2.92 (K, annual, 195-230(Loo),and -0.03-0.08 years (to). Maximum size in the demersal phase is 230 mm TL in the northwestern Gulf, but more typically only 200-205 mm. Typical maximum life span (tL) is about 1 year but may exceed that if individuals survive in a pelagic stage after spawning. Apparent mean time and cohort-specific total annual mortality rates are 97-100% in the northwestern Gulf. Population dynamics parameters presented are termed apparent because of the unknown effects of recruitment, movements, random variation, gear selectivity, etc. Spawning grounds seemingly lie along the Outer Continental Shelf, slope, or further offshore, and currents of the cyclonic shelf gyre off Texas and western Louisiana transport the young to estuarine and inshore nurseries.

Attraction of Zebrafish, Brachydanio rerio, to Alanine and its Suppression by Copper. C.W. Steele, D.W. Owens and A.D. Scarfe. In J. Fish Biol (1990) 36: 341-352. TAMU-SG-91-803.

Preference responses of zebra fish to 10-3, 10-4 and 10-5 M alanine (Ala) were concentration-dependent. Behavioural responses to copper (Cu) and Cu + Ala mixtures were also assessed. Zebrafish avoided 100 and 10 µg Cu 1-1, but not 1 µg 1-1. Mixtures of 10-3M Ala + 100 µg Cu 1-1 and 10-4 M Ala = 1 µg Cu 1-1 did not differ statistically from controls (no detectable preference or avoidance). These results demonstrate, firstly, that a concentration of a pollutant avoided by itself (10 µg Cu 1-1) may not be avoided when encountered with an attractant chemical stimulus (Ala) and may supress the preference for an attractant stimulus, and secondly, that a concentration of a pollutant not avoided by itself and not considered deleterious (1µg Cu 1-1) suppresses attraction to Ala ( an important constituent of prey odours for many fishes).

A Quantitative Analysis of Courtship Behavior in Captive Green Sea Turtles (Chelonia mydas). D.K. C. Comuzzie and D.W. Owens. In Herpetologica, 46(2): 195-202. 1990. TAMU-SG-91-804.

Reproductive behavior of captive green sea turtles (Chelonia mydas) was observed at the Cayman Turtle Farm, British West Indies. Observed components of courtship behavior included gular rubbing, biting, cloacal checking, circling and biting, chasing, following, attempted mounting, mounting, and escorting. Data analysis indicated that in each of the observed components, reproductively attractive females were the target of the behavior significantly more often than reproductively non attractive females. Cloacal checks may be used by both males and females to assess reproductive condition of females. Males may escort mounted pairs to disrupt copulation attempts by rivals and increase their own reproductive success; females may act as escorts to enhance later mate availability. In general, females appear to signal approaching reproductive receptivity to males, but females may exercise mate selectivity by avoiding mounting.

Isolation and Identification of a New Cembranoid Diterpene from the Tunicate Sytela plicata. J.M. Wasylyk and M. Alam. In Journal of Natural Products. Vol. 52, No 6, PP. 1360-1362, Nov-Dec 1989. TAMU-SG-91-805.

We report the isolation of a novel cembrane, diterpene styelolide {1}, from the tunicate Styela plicata. The structure of the new diterpene was determined by utilizing 2D nmr techniques.

Isolation, Synthesis, and Evaluation of a Series of Indencarbazates as Hypotensive Agents. T.L. Lemke, R. Sanduja, M.M. Mroue, S. Iyer, M. Alam, M.B. Hossain, and D. van der Helm. In Journal of Pharmaceutical Sciences, Vol. 79, No. 9, September 1990. TAMU-SG-91-806.

Two idencarbazates, 1 and 2, were isolated from the sponge Cliona caribboea. These compounds were found to possess mild hypotensive activity. A series of analogues of 1 was synthesized in order to study the structure-activity relationship of this unique class of compounds. A variety of structural changes did not result in a consistent pattern of biological activity.

Ultrasound Imaging of Reproductive Organs and Eggs in Galapagos Tortoises, Geochelone elephkantopus spp. T.R. Robeck, D.C. Rostal, P.M. Burchfield, D.W. Owens, and D. C. Kraemer. In Zoo Biology 9:349-359 (1990). TAMU-SG-91-810.

This study demonstrates the efficacy of using ultrasound to determine the presence of ovarian developing, preovulatory, and atretic follicular structures and oviductal eggs in the Galapagos tortoise, Geochelone elephantopus spp. Ultrasound was effective in locating both right and left ovarian structures in 92 percent (n = 100 ovaries) of the trials. Developing and preovulatory follicles and oviductal eggs were echogenically visualized and had measurements ranging from 18 to 44 mm (n = 93) and 55 to 68 mm (n = 9), respectively. Atretic follicles ranged in size from 10 to 38 mm (n = 10). In one trial with four G. elephantopus, ultrasound observations were validated with the use of laparoscopy. All procedures were accomplished without general anesthesia on a specifically designed restraining table. Ultrasound provides an effective, safe modality for determining the reproductive status of adult female tortoises.

1991-92

Effects of Group Size on the Responsiveness of Zebrafish, Brachydanio rerio (Hamilton Buchanan), to Alanine, a Chemical Attractant. C.W. Steele, A.D. Scarfe and D.W. Owens. 1991. Journal of Fish Biology 38: 553-564. TAMU-SG-92-801.

Previous studies have examined the effects of grouping on the locating (search) phase of foraging and feeding behaviour in fishes. Few studies have examined whether schooling in fishes may facilitate individual foraging by enhancing a group's responsiveness to food odours. The purpose of the current study was to assess the effect of increasing group size on the responsiveness of zebrafish, Brachydanio rerio, to L-alanine, an amino acid which is an important constituent of prey odours for many fishes. Based on the results of previous studies, either an increasing or decreasing linear relationship or a unimodal (convex or concave) relationship between responsiveness and group size was expected; the results, however, were bimodal. Groups of four fish were most responsive to alanine, as determined by the mean percentage of occurrences of fish in the area of a behavioural arena (an octagonal fluviarium) into which alanine was infused (at 10-3, 10-4, or 10-5 M). Groups of two, six and eight fish were significantly less responsive (P<0.05) than either groups of four fish or individual fish. The responses of groups of two, six and eight fish were not significantly different from each other.

Soft Plastra of Adult Male Sea Turtles: An Apparent Secondary Sexual Characteristic. Thane Wibbels, David W. Owens and David Rostal. 1991. Herp Review. 22(2): 47-49. TAMU-SG-92-803.

In contrast to many turtle species, chelonid sea turtles do not exhibit sexual size dimorphism. However, chelonid sea turtles do have several sexual dimorphisms that appear to facilitate successful mating. Collectively, these morphological characteristics enhance a male's ability to successfully mount a female. These secondary sexual characteristics also provide a means by which investigators can sex adult chelonid turtles and thus, are of importance to population studies.

Use of Ultrafiltration to Isolate Viruses from Seawater which are Pathogens of Marine Phytoplankton. Curtis A. Suttle, Amy M. Chan and Matthew T. Cottrell. 1991. Applied and Environmental Microbiology. 57(3): 721-726. TAMU-SG-92-804.

Viruses may be major structuring elements of phytoplankton communities and hence important regulators of nutrient and energy fluxes in aquatic environments. In order to ascertain whether viruses are potentially important in distating phytoplankton community structure, it is essential to determine the extent to which representative phytoplankton taxa are susceptible to viral infection. We used a spiral ultrafiltration cartridge to concentrate viruses from seawater at efficiencies approaching 100 percent. Natural virus communities were concentrated from stations in the Gulf of Mexico, a barrier island pass, and a hypersaline lagoon (Laguna Madre) and added to cultures of potential phytoplankton hosts. By following changes in in vivo fluorescence over time, it was possible to isolate several viruses that were pathogens to a variety of marine phytoplankton, including a prasinophyte (Micromonas pusilla), a pennate diatom (likely a Navicula sp.), a centric diatom (of unknown taxa), and a chroococcoid cyanobacterium (a Synechoccus sp.). As well, we observed changes in fluorescence in cultures of a cryptophyte and a chlorophyte which were consistent with the presence of viral pathogens. Although pathogens were isolated from all stations, all the pathogens were not isolated from every station. Filterability studies on the viruses infecting M. pusilla and the Navicula sp. showed that the viruses were consistently infective after filtration through polycarbonate and glass-fiber filters but were affected by most other filter types. Establishment of phytoplankton-pathogen systems will be important in elucidating the effect that viruses have on primary producers in aquatic systems.

Reproduction, Age and Growth, and Movements of the Gulf Butterfish Peprilus burti. Michael D. Murphy and Mark E. Chittenden, Jr. 1991. Fishery Bulletin. 89: 101-116. TAMU-SG-92-808.

Collections were made for gulf butterfish Peprilus burti along a cross-shelf transect at depths of 5-100 m in the Gulf of Mexico off Texas from October 1977 to July 1980. Butterfish mature at 100-160 mm fork length as they approach age I. Spawning occurs primarily from September through May, but length frequencies indicate it concentrates, or is most successful, in distinct "Winter" (late January-mid-May) and "Fall" (early September-late October) periods that coincide with downcoast, alongshore currents (toward Mexico). Gonad data and persistence of small fish indicate spawning in winter, but at a low level. Spawning probably occurs offshore and upcoast toward the northcentral Gulf. Surface currents of the cyclonic shelf gyre probable transport eggs/larvae inshore and downcoast to recruit to the bottom in water 5-27 m deep, used as nurseries by butterfish when they are 2-5 months old. Butterfish disperse offshore as they mature and congregate in 36-100 m depths when they are 9-12 months old. They average 130-146 mm in fork length at age I in the northwestern Gulf, but 120-124 mm at age I and about 170 mm at age II in the northcentral Gulf. Somatic growth ceases as spawning approaches in the northwestern Gulf, but fish from the northcentral Gulf show large annual size increments. Butterfish reach about 200 mm in fork length, the largest ones occurring in the northcentral Gulf. Apparent maximum ages are 1-1.5 years in the northwestern Gulf and 2-2.5 years in the northcentral Gulf. Differences in population attributes suggest complete mortality at age I in the northwestern Gulf or some unknown combination of an offshore and permanent contranatant spawning or postspawning emigration of adults to the northcentral Gulf.

Extensive Polymorphism at Adenosine Deaminase in the Marine Fish Sciaenops ocellatus (L.). D.A. Bohlmeyer and J. R. Gold. 1990. Animal Genetics 21: 211-213. TAMU-SG-92-810.

Eleven different allelic variants at the adenosine deaminase (ADA) locus have been detected using vertical starch-gel electrophoresis among 474 individuals of the marine fish Sciaenops ocellatus (L.). Thirty-five of the 66 possible genotypes were observed, and the heterozygosity level at ADA was estimated to be 70.3 percent. The extensive polymorphism at ADA may prove useful in terms of providing genetic markers for stocking programs using hatchery-raised fish.

Restriction Site Heteroplasmy in the Mitochondrial DNA of the Marine Fish Sciaenops ocellatus (L.). J.R. Gold and L.R. Richardson. 1990. Animal Genetics 21: 313-316. TAMU-SG-92-811.

Restriction site heteroplasmy involving the enzymes Ncol and Xbal was detected in the mitochondrial DNAs of two individuals of the marine fish Sciaenops ocellatus. This represents only the sixth documented example of mitochondrial DNA restriction site heteroplasmy in animals. Two heteroplasmic individuals were found in a survey of nearly 750 individuals, suggesting that in most studies the incidence of mitochondrial DNA site heteroplasmy may be too low to be routinely detected.

Genetic Studies in Marine Fishes II. A protein electrophoretic analysis of population structure in the red drum Sciaenops ocellatus. D.A. Bohlmeyer and J.R. Gold. 1991. Marine Biology 108: 197-206. TAMU-SG-92-812.

Nine polymorphic loci were found among 42 presumptive protein-coding gene loci surveyed among 474 red drum (Sciaenops ocellatus) sampled in 1987 from 13 nearshore and 1 offshore localities from the Atlantic coast of the southeastern USA and the northern Gulf of Mexico. The mean number of alleles over the polymorphic loci was 3.8, and the average heterozygosity over all loci examined was estimated as 0.047. These data indicate that red drum have "normal" levels of genetic variability. Wright's FST values (the standardized variance of allele frequencies between samples) over all polymorphic loci ranged from 0.009 to 0.027 (mean FST = 0.019), and estimates of the effective number of migrants (Nem) per generation using Wright's island model ranged from 9.0 to 27.5. High levels of gene flow among the red drum samples were also indicated by Slatkin's qualitative analysis using conditional average allele frequencies. Nei's estimates of genetic distance between pairs of samples ranged from 0.000 to 0.009, indicating a high degree of nuclear gene similarity among all samples. Highly significant heterogeneity in allele frequencies at the locus for adenosine deaminase was detected between red drum sampled from the Atlantic and those sampled from the Gulf and among red drum sampled from the Gulf.

A Polyclonal Antibody Developed from Perkinsus marinus Hypnospores Fails to Cross React with Other Life Stages of P. marinus in Oyster (Crassostrea virginica) Tissues. Kwang-Sik Choi, Donald H. Lewis, Eric N. Powell, Paul F. Frelier and Sammy M. Ray. 1991. Journal of Shellfish Research 10(2): 411-415. TAMU-SG-92-814.

Polyclonal antiserum was produced from Perkinsus marinus hypnospores harvested from oyster tissue cultivated in fluid thioglycollate medium. The specificity of the antiserum for hypnospores was tested using indirect sandwich ELISA with alkaline phosphatase-conjugated goat anti-rabbit IgG and indirect immunofluorescence. As little as 20 ng of hypnospore protein could be detected by ELISA. Immunofluorescence assays suggested that the antigenic material was a component of the spore cell wall. Cross reactivity of the antiserum to other life stages of P. marinus present in oyster tissues could not be demonstrated by ELISA or immunofluorescence indicating that a substantial change in the antigenic properties of the cell wall occurs during spore formation. Hypnospore formation was also induced by placing P. marinus-infected oyster tissues into an anaerobic chamber rather than fluid thioglycollate. Spores were positively identified by ELISA, however little spore enlargement occurred suggesting that the triggering mechanisms for spore formation is not the same as that for enlargement.

Female-biased sex ratio of immature loggerhead sea turtles inhabiting the Atlantic coastal waters of Florida. Thane Wibbels, R. Erik Martin, David W. Owens and Max S. Amoss, Jr. 1991. Can. Journal of Zoology 69: 2973-2977. TAMU-SG-92-818.

The sex ratio of immature loggerhead sea turtles, Caretta caretta, inhabiting the Atlantic coastal waters of Florida was investigated. Blood samples were obtained from 223 turtles that were captured in the intake channel of a power plant on Hutchinson Island. A serum androgen sexing technique was utilized to sex individual turtles. The sex ratio of the turtles (2.1 female : 1.0 male) differed significantly from 1:1 and thus appears to differ from predictions of sex allocation theory. These observations are consistent with those of a previous study, and collectively the results suggest that the sex ratio of immature C. caretta inhabiting the Atlantic coastal waters of the United States is significantly female biased: approximately two females per male.

1992-93

Fuel Efficiency Analysis of Trawl Nets in the Gulf of Mexico Shrimp Fisheries. Gary L. Graham and Dewayne Hollin. January 1993. 6 pp, 10 charts. TAMU-SG-93-502.

Commercial shrimping is a fuel-intensive industry. More than one-third of the diesel fuel consumed in the U.S. fisheries is by Gulf of Mexico shrimp vessels, and more than 70 percent of this consumption is associated with trawling during shrimping operations. Eighty percent of the overall pull on the gear is distributed on the trawl nets. This report summarizes a project funded by the Texas Governor's Energy Office to test and evaluate the efficiency of using lightweight, more technical webbing while shrimp fishing. The report analyzes and describes the types of webbing and the various weights as well as how much fuel was saved while trawling with the high-tech webbing.

Isolation of Maturational Gonadotropin Subunits from Spotted Seatrout (Cynoscion nebulosus) and Development of a ß-Subunit-Directed Radioimmunoassay for Gonado-tropin Measurement in Sciaenid Fishes. Paul A. Copeland and Peter Thomas. 1992. General and Comparative Endocrinology 88: 100-110. TAMU-SG-93-808.

Maturational gonadotropin (GTH) subunits were isolated from pituitaries of the spotted seatrout (Cynoscion nebulosus), a marine perciform teleost, by ethanolic extraction and ion-exchange, gel-filtration, and reverse-phase chromatography. Partial amino acid sequencing of the N-terminal regions of the alpha and beta subunits indicated 60-80% identities with various carp and salmon GTH subunits. The spotted seatrout GTH beta-subunit was used as radioligand in a radioimmunoassay (RIA) with Atlantic croaker (Micropogonias undulatus) GTH antiserum. Pituitary extracts and plasmas from a variety of sciaenid fishes diluted parallel to the croaker GTH standard in the RIA. These data suggest that there is a high degree of immunological similarity among the GTH beta subunits of sciaenid fishes. The RIA measured levels of GTH in the plasmas of three species of sciaenid fishes, spotted seatrout, orangemouth corvina (Cynoscion xanthulus), and red drum (Sciaenops ocellatus), following injections of a luteinizing hormone-releasing hormone analog. The beta-subunit-directed GTH RIA increases considerably the number of species in which studies of GTH physiology can now be conducted.

Adrenal-Kidney and Gonadal Steroidogenesis during Sexual Differentiation of a Reptile with Temperature-Dependent Sex Determination. Richard B. White and Peter Thomas. 1992. General and Comparative Endocrinology 88: 10-19. TAMU-SG-93-809.

Adrenal-kidney and gonadal steroidogenesis were studied during early development in the red-eared slider turtle, Trachemys scripta, which exhibits temperature-dependent sex determination. In vitro steroid secretion by adrenal-kidney-gonad complexes (AKGs) incubated for six hr was determined by radioimmunoassay (RIA). AKGs from presumptive males and females secreted progesterone at developmental stages before (stage 15), during (stages 17 and 19), and after (stage 21) the temperature-sensitive period for sex determination, and progesterone secretion increased significantly throughout the period from stage 15 to 21. Presumptive male AKGs secreted significantly more progesterone than female AKGs at stage 19. Corticosterone secretion by AKGs was observed at stage 17 in males only, but in both sexes at stages 19 and 21. Testosterone, estradiol, androstenedione, and dehydroepiandrosterone secretion by AKGs was detected only at stage 21. Of the steroids measured, progesterone and corticosterone were consistently secreted at the highest levels. Although some sex differences were observed, no obvious patterns of sexually dimorphic steroid secretion from AKGs were apparent. Gonads from stage 21, stage 24, and 10-day-old hatchlings from both presumptive sexes incubated with [7-3H]pregnenolone showed only weak precursor conversion, primarily to polar metabolites, in incubations as long as 24 hr. None of the steroids assessed by RIA of AKG incubates could be identified by TLC or HPLC analysis of the stage 21 and stage 24 gonadal incubates. However, proges-terone was tentatively identified in incubates of 10-day post-hatch female gonads. For stage 21 females, AKGs were separated into gonadal and adrenal-kidney tissue (AK) components and incubated in vitro for 1, 3, and 18 hr. Secretion of progesterone, testosterone, estradiol, and corticosterone from gonads was nondetectable by RIA, whereas secretion of progesterone and corticosterone by AKs was evident at all three time points and testosterone was detected in the media after 18 hr of incubation. Tissues from these incubations were extracted and assayed for progesterone and testosterone; neither of these steroids was detected in gonads and only progesterone was detected in AKs. These results indicate that the gonads are relatively quiescent, whereas adrenal-kidney tissue is steroidogenically active before, during and after the temperature-sensitive period for sex determination in T. scripta.

Spatial and temporal distributions of contaminant body burden and disease in Gulf of Mexico oyster populations: The role of local and large-scale climatic controls. E.A. Wilson, E.N. Powell, T.L. Wade, R.J. Taylor, B.J. Presley and J.M. Brooks. 1992. Helgoländer Meeresuntersuchungen 46: 201-235. TAMU-SG-93-815.

As part of NOAA's Status and Trends Program, oysters were sampled from 43 sites throughout the Gulf of Mexico from Brownsville, Texas, to the Florida Everglades from 1986 to 1989. Oysters were analyzed for body burden of a suite of metals and petroleum aromatic hydrocarbons (PAHs), the prevalence and intensity of the oyster pathogen, Perkinsus marinus, and condition index. The contaminants fell into two groups based on the spatial distribution of body burden throughout the Gulf. Arsenic, selenium, mercury and cadmium were characterized by clinal reduction in similarity with distance reminiscent of that followed by mean monthly temperature and precipitation. Zinc, copper, PAHs and silver showed no consistent geographic trend. Within local regions, industrial and agricultural land use and P. marinus prevalence and infection intensity frequently correlated with body burden. Contaminants and biological attributes followed one of three temporal trends. Zinc, copper and PAHs showed concordant shifts over 4 years throughout the eastern and southern Gulf. Mercury and cadmium showed concordant shifts in the northwestern Gulf. Selenium, arsenic, length, condition index and P. marinus prevalence and infection intensity showed concordant shifts throughout most of the entire Gulf. Concordant shifts suggest that climatic factors, the El Niño/Southern Oscillation being one example, exert a strong influence on biological attributes and contaminant body burdens in the Gulf. Correlative factors are those that probably affect or indicate the rate of tissue turnover and the frequency of reproduction; namely, temperature, disease intensity, condition index and length.

Oyster Disease and Climate Change. Are Yearly Changes in Perkinsus marinus Parasitism in Oysters (Crassostrea virginica) Controlled by Climatic Cycles in the Gulf of Mexico? Eric N. Powell, Julie D. Gauthier, Elizabeth A. Wilson, Alanna Nelson, Roger R. Fay and James M. Brooks. 1992. Marine Ecology 13(3): 243-270. TAMU-SG-93-816.

The protozoan Perkinsus (=Dermocystidium) marinus is the most important pathogen of eastern oysters (Crassostrea virginica) in the Gulf of Mexico. Prevalence of P. marinus has been related to salinity and temperature, with low temperatures and salinities usually limiting infection. In 1986, a yearly monitoring program was begun to describe the regional distribution and yearly trends in P. marinus prevalence and infection intensity in the Gulf of Mexico in connection with NOAA's Mussel Watch program. Between 1986 and 1989, prevalence and infection intensity dropped in the southeastern and southwestern Gulf, infection intensity most strongly, and rose in the Florida panhandle, prevalence most strongly. Infection intensity fell but prevalence rose on both sides of the Mississippi delta; central/north Texas remained essentially unchanged. The regional and temporal distribution of P. marinus in the Gulf of Mexico can be considered a product of two spatio-temporal phenomena. (1) A relatively stable spatial pattern exists each year with centers of infection on the order of 300 km. (2) A concordance in yearly shifts in prevalence and infection intensity occurs among sites on a scale of » 1,000 km. The spatial scale of concordant yearly changes is much larger than the scale of centers of infection, and probably originates in broad shifts in weather patterns as they affect temperature and salinity (via rainfall and river runoff). Long-term climatic changes are most likely responsible for these spatio-temporal shifts and, as such, P. marinus prevalence and infection intensity may eventually be predictable from climatic models. Our data demonstrate the importance of multi-year cycles, not just seasonal cycles and occasional heavy rains, in determining P. marinus prevalence and implicate salinity as the primary mediating factor.

An Improved Method for Mapping Oyster Bottom Using a Global Positioning System and an Acoustic Profiler. James D. Simons, Thomas M. Soniat, Eric N. Powell, Junggeun Song, Matthew S. Ellis, Stephanie A. Boyles, Elizabeth A. Wilson and W. Russell Callender. 1992. Journal of Shellfish Research 11(2): 431-436. TAMU-SG-93-817.

A method for rapidly and relatively inexpensively mapping oyster bottom is described. The method uses an acoustic profiler to differentiate substrate type, a fathometer to assess bottom relief and a global positioning system to accurately establish position. The method has the following desirable traits: can be performed from a small research vessel, usable in most weather conditions, requires only a two-person crew, rapidly discriminates bottom type while underway, usable in shallow (<1 m) or deep (>10 m) water, provides accurate and precise navigation. The method has been used successfully to map the oyster reefs and oyster bottom of Galveston Bay, Texas, an area of approximately 1000 km2.

Modeling Oyster Populations I. A Commentary on Filtration Rate. Is Faster Always Better? E.N. Powell, E.E. Hofmann, J.M. Klinck and S.M. Ray. 1992. Journal of Shellfish Research 11(2): 387-398. TAMU-SG-93-818.

The measurements reported in the literature that relate bivalve size to filtration rate tend to fall on one of two curves. The upper curve predicts filtration rates at a given size which are about three times those of the lower. A time-dependent numerical model for population dynamics and energy flow in post-settlement oyster populations was used to compare the effect of these two filtration versus size relationships on simulations of population growth and reproductive effort. The growth rates, fecundity, size and reproductive season of the simulated populations agree with measurements obtained from field populations only if the lower curve is used; unless the present consensus for the oyster's assimilation efficiency, the effect of high food supply on the oyster's feeding efficiency, or the measurement of oyster food supply are substantially in error. The results of these simulations question the tendency to accept higher filtration rates as more accurate for modeling field populations and suggest that an evaluation of measurements of components of the energy budget can only be made within the context of the species' complete energy budget.

A Restriction Enzyme Map of the Mitochondrial DNA of Red Drum, Sciaenops ocellatus (Osteichthys: Sciaenidae). Timothy R. Schmidt and John R. Gold. 1992. Northeast Gulf Science 12(2): 135-139. TAMU-SG-93-822.

Over the last four years, we have been studying genetic variation and its geographic distribution in the red drum or redfish, Sciaenops ocellatus. The primary purpose of the study was to determine if separate stocks or breeding assemblages of red drum occur in the northern Gulf of Mexico or along the Atlantic coast of the southeastern United States. The primary genetic assay has been analysis of restriction fragment length polymorphisms (RFLPs) of red drum mitochondrial (mt) DNA (Gold and Richardson 1990, 1991, unpubl.). A second purpose of the study was to uncover genetic markers that would be useful as tags in red drum stock enhancement or aquaculture programs. In Texas and other southeastern Gulf and Atlantic Coast states, several management units have initiated red drum stocking programs as a means to revitalize the historic red drum fishery (Dailey and Matlock 1987). Vital to evaluating the success of the stock enhancement programs will be genetic tags that can be used to discriminate among wild and hatchery-raised individuals. To date, our studies of both red drum mtDNA and nuclear genes (the latter resolved using protein electrophoresis) have shown that red drum are weakly subdivided, with semi-isolated subpopulations or stocks occurring along the southeastern Atlantic Coast and in the northern Gulf of Mexico (Bohlmeyer and Gold, 1991, Gold and Richardson, 1991, unpubl.). MtDNA, in particular, has been found to vary considerably in red drum. One hundred and twenty-nine (129) different mtDNA genotypes or haplotypes have now been documented among >1,000 red drum surveyed (Gold and Richardson, 1991, unpubl.). Of the 129 different mtDNA haplotypes, eleven were found in more than 30 individuals, seven were found in 11-30 individuals, 23 were found in in 4-10 individuals, 19 were found in 2-3 individuals, and 69 were unique to individual fish. The high incidence of rare mtDNA genotypes suggests that mtDNA markers could prove highly effective as genetic tags in stocking programs. Reasons why mtDNA markers might be preferable to nuclear gene markers were given in Gold and Richardson (1991). In this paper, we provide a restriction enzyme site map of red drum mtDNA. The map contains 123 different sites for 18 different, type II restriction endonucleases. Ninety-three (93) of the sites have thus far been found to be variable or "polymorphic" in red drum (Gold and Richardson 1991, unpubl.).

Swimming performance of captive-reared Kemp's ridley sea turtles Lepidochelys kempi (Garman). Erich K. Stabenau, André M. Landry, Jr. and Charles W. Caillouet, Jr. 1992. J. Exp. Mar. Biol. Ecol. 161: 213-222. TAMU-SG-93-824.

Swimming performance of Kemp's ridley sea turtles Lepidochelys kempi (Garman) was evaluated over a 6-month period to determine whether an exercise regime increased swimming capacity in captive reared turtles. Three experimental treatments included: (1) turtles exercised twice weekly and exposed to a weekly stamina test; (2) turtles subjected only to a weekly stamina test; and (3) non-exercised controls exposed to a single stamina test at the end of the study. No statistically significant difference in swimming capacity was detected between treatments 1 and 2, although treatment 1 turtles achieved higher performance levels than those from treatment 2. However, treatment 1 turtles exhibited fewer breaths/min (BRM) and foreflipper strokes/min (FSM) during stamina tests than did treatment 2 turtles. In contrast, control turtles (treatment 3) were unable to achieve the minimum swimming performance level. These results indicate that the swimming performances of exercised turtles significantly improved during captive rearing. The possible effects of an exercise regime on post-release survival potential are discussed.

Field Studies Using the Oyster Crassostrea virginica to Determine Mercury Accumulation and Depuration Rates. Sally J. Palmer, Bobby J. Presley, Robert J. Taylor and Eric N. Powell. 1993. Bull. Environ. Contam. Toxicol. 51: 464-470. TAMU-SG-93-825.

Mercury as an environmental hazard, especially with regard to human health, has been of concern since the Minamata disaster (Huddle et al. 1975). From 1966 to 1970 a chlor-alkali plant in Point Comfort, Texas released mercury-enriched wastewater (up to 29.9 kgHg/day) into Lavaca Bay (TWQB 1977). Since 1970 the Texas Department of Health (TDH) has periodically closed and then re-opened portions of Lavaca Bay to the harvesting of crabs and finfish based on their levels (< >0.5 ppm Hg wet weight) of mercury. A 1988 closure remains in effect as of this writing (Wiles, 1993). Mercury contamination in Lavaca Bay organisms thus continues to be a problem 22 years after the chlor-alkali plant ceased releasing mercury into the bay. The goal of the following research was to better understand the behavior of mercury in Lavaca Bay. Oysters have been widely used as an indicator species in metal pollution studies (Goldberg et al. 1983). Most such programs have focused on the concentrations of metals in oysters from different geographic areas. This study, however, investigated the rate and amount of mercury a "clean" oyster would accumulate when transplanted to a contaminated estuary and the rate of mercury depuration by contaminated oysters placed in a clean environment. The oysters were additionally analyzed for Ba, Cu, Fe, P, and Zn to test for the possible involvement of these metals in mercury accumulation and depuration.

1993-94

Quantitative Measurement of Reproductive Output in the American Oyster, Crassostrea virginica (Gmelin), Using an Enzyme-Linked Immunosorbent Assay (ELISA). Kwang-Sik Choi, Donald H. Lewis, Eric N. Powell and Sammy M. Ray. In Aquaculture and Fisheries Management, 24, 299-322 (1993). TAMU-SG-94-801.

A quantitative gonadal index was developed for the American Oysters using polyclonal antibodies from eggs and sperm. Percoll used in the purification of oyster eggs and sperm greatly improved the purity of antigens compared to filtering the egg or sperm through a fine mesh only. The antigen-antibody reaction was tested with indirect sandwich ELISA using alkaline phosphatase-conjugated goat anti-rabbit IgG as a secondary antibody. Rabbit anti-oyster egg IgG and anti-oyster sperm IgG initially exhibited a weak cross-reactivity over somatic tissue. Both antisera exhibited strong specific immunological reactions to oyster eggs or sperm, respectively. The quantity of eggs or sperm was measured using ELISA and a quantitative gonadosomatic index (dry wt of egg or sperm/dry wt oyster) (GSI) was calculated. GSI from ELISA correlated with gonadal stage measured histologically.

Detection of Enteric Viruses in Oysters by Using the Polymerase Chain Reaction. Robert L. Atmar, Theodore G. Metcalf, Frederick H. Neill and Mary K. Estes. In Applied and Environmental Microbiology, Vol. 59(2), 631-635 (1993). TAMU-SG-94-803.

A procedure for the detection of enteric viral nucleic acid in oysters by the polymerase chain reaction was developed. Known quantities of poliovirus type 1 were seeded into oysters. Virus was extracted and concentrated by using organic flocculation and polyethylene glycol precipitation. Inhibitors of reverse transcription-polymerase chain reaction were present in the oyster extracts, preventing amplification of target viral nucleic acid. The use of cetyltrimethylammonium bromide precipitation sufficiently removed inhibitors to allow detection of as few as 10 PFU of poliovirus. Norwalk virus also could be detected after being seeded into oysters. This methodology may be useful for the detection of these and other shellfish-borne viral pathogens.

Sex Ratio of Immature Green Turtles Inhabiting the Hawaiian Archipelago. Thane Wibbels, George H. Balazs, David W. Owens and Max S. Amoss, Jr. In Journal of Herpetology, Vol. 27 (3), 327-329 (1993). TAMU-SG-94-806.

A variety of reptiles possess temperature-dependent sex determination (TSD), including all species of sea turtles examined to date. Sea turtle sex ratios resulting from TSD are of ecological and conservational significance, since they affect reproduction. Further, a comprehensive knowledge of naturally-occurring sex ratios is a prerequisite for understanding the evolutionary basis of the wide range of sex ratios reported for reptiles with TSD. In the current study, a serum androgen sexing technique is used to estimate the sex ratio of immature green turtles, Chelonia mydas, inhabiting certain foraging grounds of the Hawaiian Archipelago.

Genetic Distinctness of Red Drum (Sciaenops ocellatus) form Mosquito Lagoon, East-Central Florida. John R. Gold and Linda R. Richardson. In Fishery Bulletin, 92, 58-66 (1994). TAMU-SG-94-808.

Red drum from Mosquito Lagoon, east-central Florida, were examined for variation in products of nine polymorphic nuclear-gene (allozyme) loci and in mitochondrial (mt)DNA restriction sites. Genetic data from Mosquito Lagoon fish were compared to similar data from red drum sampled from the northeastern Gulf of Mexico and the Carolina coast of the southeastern U.S. Significant heterogeneity among red drum from the three areas was found in the frequencies of inferred alleles at two to three allozyme loci and in the frequencies of six mtDNA haplotypes. Red drum from Mosquito Lagoon were as differentiated genetically from red drum in the northeastern Gulf and Carolina coast as the latter two were from each other. Genetic data are consistent with the hypothesis that red drum in Mosquito Lagoon are self-contained and at least partially isolated from red drum in other U.S. waters.

A Determination of In Vivo Growth Rates for Perkinsus marinus, a Parasite of the Eastern Oyster Crassostrea virginica. Georgianna L. Saunders, Eric N. Powell and Donald H. Lewis. In Journal of Shellfish Research, Vol. 12 (2), 229-240 (1993). TAMU-SG-94-809.

Perkinsus marinus exerts a significant controlling influence on oyster population dynamics over much of its range. The rate of DNA synthesis in P. marinus was measured by following the rate of incorporation of 14C-aspartic acid under field conditions. The DNA content in each P. marinus hypnospore was approximately 1 pg. The growth rate in the oyster host is dependent upon P. marinus population density. When the parasites occur at densities of greater than 104 cells g dry wt oyster-1, P. marinus exhibited an increase in population doubling time. At low cell density, doubling times of 1 to 10 hr were obtained. Doubling time increased to >104 hr at near-lethal infection levels. One important consequence of the growth dynamics of P. marinus is the importance of the parasite in controlling its own population levels. Infection intensity in the summer was controlled by the feedback of P. marinus cell density on doubling time.

Instantaneous Reproductive Effort in Female American Oysters, Crassostrea virginica, Measured by a New Immunoprecipitation Assay. Kwang-Sik Choi, Eric N. Powell, Donald H. Lewis and Sammy M. Ray. In Biol. Bull., 86, 41-61 (1994). TAMU-SG-94-810.

An immunoprecipitation assay was developed for measuring instantaneous reproductive effort in female American oysters. Oysters were injected with 14C-leucine and incubated in situ for 1 to 30 h periodically throughout the annual gametogenic cycle. Gonadal protein labeled with 14C-leucine was precipitated from an oyster homogenate with rabbit anti-oyster egg IgG as the primary antibody. Antibody-oyster egg protein complex was further purified by immunoadsorption with staphylococcal protein A cell suspension. The oyster population was lightly to moderately infected with a protozoan parasite, Perkinsus marinus. A negative correlation between the intensity of infection and the rate of gonadal production suggest that P. marinus retards the rate of gamete development. The range in observed somatic and gametic growth emphasizes the conservatism of somatic growth and the volatility of gonadal growth that is borne out by the results of population dynamics models of oysters.

Taphonomic Rates of Molluscan Shells Placed in Autochthonous Assemblages on the Louisiana Continental Slope. W. Russell Callender, Eric N. Powell and George M. Staff. In Palaios, 9, 60-73 (1994). TAMU-SG-94-812.

A mixed assemblage of lucinid and mussel shells were placed in mesh bags and left at a site of autochthonous death assemblage formation in a petroleum seep community on the Louisiana upper continental slope for a period of 3 yr. Upon recovery, the shells were assessed for taphonomic alteration and compared to a control assemblage of unaltered shells. The data verify a basic assumption of taphofacies analysis; that evidence of taphonomic processes preserved with the assemblage does in fact document the primary taphonomic processes that biased the assemblage from the original assemblage of living preservable organisms. Significant variability in taphonomic rates existed between shells from locations 10 m apart, as is typical of autochthonous assemblages, so that small-scale variability in the taphonomic process was important. Mussels were more severely altered than lucinids.

1994-95

Modeling Oyster Populations. IV: Rates of Mortality, Population Crashes and Management. Eric N. Powell, John M. Klinck, Eileen E. Hofmann and Sammy M. Ray. In Fishery Bulletin, 92(2), 347-373 (1994). TAMU-SG-95-801.

A time-dependent energy-flow model was used to examine how mortality affects oyster populations over the latitudinal gradient from Galveston Bay, Texas, to Chesapeake Bay, Virginia. Simulations using different mortality rates showed that mortality is required for market-site oysters to be a component of the population's size-frequency distribution; otherwise a population of stunted individuals results. Comparison of simulations of Galveston Bay and Chesapeake Bay showed that oyster populations are more susceptible to intense population declines at higher latitudes. The association of population declines with disease agents causing summer mortality and the increased frequency of long-term declines at high latitudes result from the basic physiology of the oyster and its population dynamics cycle.

Modeling Oyster Populations II. Adult Size and Reproductive Effort. Eileen E. Hofmann, John M. Klinck, Eric N. Powell, Stephanie Boyles and Matthew Ellis. In Journal of Shellfish Research, Vol. 13(1), 165-182 (1994). TAMU-SG-95-804.

A time-dependent model of energy flow in post-settlement oyster populations is used to examine the factors that influence adult size and reproductive effort in a particular habitat, Galveston Bay, Texas, and in habitats that extend from Laguna Madre, Texas, to Chesapeake Bay. The simulated populations show that adult size and reproductive effort are determined by the allocation of net production to somatic or reproductive tissue development and the rate of food acquisition. Variations in temperature and food supply affect reproductive effort more than adult size because the rate of energy flow through the oyster is higher in warmer months when most net production is allocated to reproduction and small changes in temperature substantially change the spawning season.

Surface Disinfection of Red Drum (Sciaenops ocellatus Linnaeus) Eggs Leading to Bacteria-Free Larvae. P.A. Douillet and G. Joan Holt. In Journal of Experimental Marine Biology and Ecology, 179, 253-266 (1994). TAMU-SG-95-805.

The effects of exposure of red drum eggs to different disinfectants on 24-h larval survival were evaluated following a toxicological approach, involving the determination of the "No Observable Effect Concentration" (NOEC) for each germicide. The NOECs of the different disinfectants were evaluated at different stages of egg development. Other marine fish species tested, yellowtail snapper and spotted seatrout, were more sensitive to hydrogen peroxide than red drum so the toxicological approach used to select the disinfection treatment for red drum should be undertaken for each target species.

1995-96

Hangs and Bottom Obstructions of the Texas/Louisiana Gulf. Gary L. Graham. February 1996. 2-volumes. TAMU-SG-96-501 ($15.00) and TAMU-SG-96-502. ($20.00)

Twenty years of reports from nearly 170 Texas captains have been compiled into two volumes that help commercial fishermen avoid and recreational fishermen find trouble spots in the Gulf of Mexico. The 1996 edition of the Hangs book is an accumulation of primarily LORAN C coordinates for known shipwrecks, rockpiles and thousands of other seabed hazards that threaten shrimp nets from the Mississippi River to the Rio Grande. It covers an area of 25,000 square nautical miles. It also serves as a guide for recreational fishermen looking for the places fish feed and hide. Together, the two volumes include 11,523 hangs, an addition of 3,400 since the 1988 edition. The readings are divided into a Nearshore volume including Fathoms 1 through 12 and an Offshore volume for Fathoms 10 through 50. Both books have expanded formats that make the coordinates more legible and allow for greater distinction between close-set hangs.

Ecological Notes and Patterns of Dispersal in the Recently Introduced Mussel, Perna perna (Linné, 1758), in the Gulf of Mexico. David W. Hicks and John W. Tunnell, Jr.. In American Malacological Bulletin, Vol. 11(2), 203-206 (1995). TAMU-SG-96-802.

Invasive mussels, Perna perna, were first detected in south Texas on the jetties at Port Aransas in February 1990. Within four years the species has colonized jetties, navigation buoys, petroleum platforms, wrecks and other artificial hard substrata as well as natural rocky shores between Matagorda Peninsula, Texas, and Playa Escondida, southern Veracruz, Mexico, a distance of over 1,300 km. Dispersal patterns interpreted from discovery data in the Gulf of Mexico indicate a primarily southward expansion from the initial recording. The occurrence of P. perna in euryhaline environments, such as river mouths and bay systems, demonstrates the ecological adaptability of this species.

Growth and Morphology of Larval and Juvenile Captive Bred Yellowtail Snapper, Ocyurus chrysurus. Cecilia M. Riley, G. Joan Holt and Connie R. Arnold. In Fishery Bulletin, 93(1), 179-185 (1995). TAMU-SG-96-804.

In this paper we describe the development and growth of laboratory spawned and reared yellowtail snapper. This species is found from Massachusetts through the Caribbean and south to Brazil. Laboratory-culture allowed us to document growth and development of the critical larval and juvenile stages of yellowtail snapper that will aid identification and aging of larval snappers collected in the field. We have also included information on the effects of a commonly used preservative (ethyl alcohol) on length measurements and pigmentation characteristics of laboratory-cultured larvae for purposes of comparative use with wild-collected larvae.

Independent Versus Socially Facilitated Oceanic Migrations of the Olive Ridley, Lepidochelys olivacea. P.T. Plotkin, R.A. Byles, D.C. Rostal, and David W. Owens. In Marine Biology, 122, 137-143 (1995). TAMU-SG-96-805.

In 1990 and 1991, we attached satellite transmitters to olive ridleys found ovipositing together during a mass nesting at Nancite Beach, Costa Rica, to determine whether they migrate independently or in groups after they leave the nesting beach. Results showed that the turtles were not spatially associated during the internesting period, were capable of re-establishing themselves as a group during a subsequent nesting emergence, and were not spatially associated during their postnesting migrations to oceanic feeding areas. We suggested that what appear to be socially structured groups of L. olivacea are in fact individual turtles simultaneously using the same habitat.

Mitochondrial DNA Diversity and Population Structure in Marine Fish Species from the Gulf of Mexico. John R. Gold, Linda R. Richardson, Carol Furman and Feng Sun. In Can. J. Fish. Aquat. Sci., Vol. 51(Suppl. 1), 205-214 (1994). TAMU-SG-96-806.

Variation in mitochondrial DNA (mtDNA) was examined among 693 red drum, 300 black drum and 421 red snapper sampled from several localities in the Gulf of Mexico. Variation in mtDNA haplotype frequencies among localities in all three species was not significant, although two mtDNA haplotypes in black drum appeared to be clinally distributed. Maximum-parsimony analysis and phenetic clustering of mtDNA haplotypes and of samples in each species revealed little evidence of phylogeographic structuring. These data indicate that gene flow among localities in each species is sufficient to preclude genetic divergence. Spatial autocorrelation analysis of mtDNA haplotype frequencies revealed an isolation-by-distance effect in red drum and black drum, and indicated that migration between neighboring estuaries or bays in black drum may be less frequent than in red drum. Spatial autocorrelations in red snapper were negative in all distance classes. Differences in intrapopulational mtDNA diversities were found in all three species.

Ecology of Infaunal Mollusca in South Texas Estuaries. Paul A. Montagna and Richard D. Kalke. In American Malacological Bulletin, Vol. 11(2), 163-175 (1995). TAMU-SG-96-814.

Long-term studies were conducted in four of the seven major estuarine ecosystems in Texas to determine the role of climatic variability and concordant differences in freshwater inflow among the ecosystems in structuring benthic infaunal communities and maintaining secondary production. The abundance, biomass and community structure of mollusks were measured along salinity gradients and infaunal samples were collected. Overall, these Texas estuaries had a mean of 14 species of infaunal mollusks, with mean abundance of 7,500 individuals/m2, and mean biomass of 2.4 g/m2. Salinity is surrogate for inflow, therefore, there are zoogeographic patterns within and among estuaries related to salinity patterns. There are seasonal, interannual and latitudinal patterns of inflow, and theses patterns are apparently regulating community structure, population dynamics and secondary production in Texas estuaries.

Departure of Male Olive Ridley Turtles (Lepidochelys olivacea) from a Nearshore Breeding Ground. Pamela T. Plotkin, David W. Owens, Richard A. Byles, and Rhonda Patterson. In Herpetologica, 52(1), 1-7 (March 1996). TAMU-SG-96-815.

Between 1990 and 1993, adult male olive ridley turtles were captured at their breeding ground, in the Gulf of Papagayo, on the Pacific coast of Costa Rica. We attached radio (VHF) and satellite (UHF) transmitters to 11 reproductively active males to monitor their movements in and from the breeding ground. Telemetered males departed the Gulf of Papagayo by late September, which coincided with a notable decrease in the number of males that we observed in the breeding ground and with the mid-season peak in the number of females emerging to lay eggs at Nancite Beach. We suggest that males of L. olivacea depart nearshore breeding grounds at mid-season because most of the females already have mated.