Vincent Guillory

Relationship of Blue Crab Abundance to River Discharge and Salinity

The relationships between 2 environmental factors (river discharge, salinity) and blue crab (Callinectes sapidus) abundance, as measured by juvenile recruitment and commercial landings, were evaluated. Correlation coefficients were calculated between a blue crab recruitment index (Jan-Feb catch-per-unit effort of individuals <40 mm carapace width) or commercial harvest and lagged or concurrent salinity and river discharge. The recruitment index was correlated with monthly means of lagged late summer/early fall Mississippi River discharge (positively) and salinity (negatively) whereas...

Food Habits of Sand Seatrout in Barataria Bay, Louisiana

Food habits of 591 sand seatrout (Cynoscion arenarius) (Ginsburg) from Barataria Bay, Louisiana, were characterized. Overall, fishes and crustaceans were the most important food organisms. Mysid shrimp were dominant food items in sand seatrout <100 mm whereas bay anchovy and brown shrimp were predominate in the larger fish. Sand seatrout generally preyed upon a relatively small number of species or taxonomic groups.

A Survey of Bycatch in the Louisiana Gulf Menhaden Fishery

A survey was made of incidental catch in the Louisiana gulf menhaden (Brevoortia patronus) purse seine fishery. Samples were taken in 1980 and 198 I at plants located at Empire, Dulac, and Cameron. Overall the bycatch comprised 2.68% by number and 2.35% by weight of the catches sampled. The most abundant species were Atlantic croaker (Micropogonias undulatus), seatrout (Cynoscion spp.), threadfin shad (Dorosoma petenense) , Atlantic bumper (Chloroscombrus chrysurus), hardhead catfish (Arius felis), and spot (Leiostomus xanthurus). Differences in species composition and abundance of bycatch...

Seasonal and Areal Abundance of Gulf Menhaden in Louisiana Estuaries

Otter trawl data from the Louisiana Department of Wildlife and Fisheries' shrimp monitoring program from 1966 through 1979 were used to determine seasonal and areal abundance of gulf menhaden in five areas along the Louisiana coast. Catches were highest in western Louisiana. Overall peaks in late winter/spring and lows in late summer/fall of catches coincide with the influx of larvae from offshore and emigration of juveniles to the Gulf, respectively.

Reproductive Biology of Chain Pickerel in Lake Conway, Florida

The reproductive biology of chain pickerel in Lake Conway, Florida was studied from July 1976 to June 1977. The overall ratio of females to males was 1.1:1.0. Spawning apparently took place in shallow water among thick Vallisneria during a sharply dermed period from December to February. Average fecundity per female was 1232. Youngest fish to spawn were 2 years old.

Evaluation Of Juvenile Menhaden Abundance Data For Prediction Of Commercial Harvest

Juvenile gulf menhaden (Brevoortia patronus) data were extracted from otter trawl surveys conducted along the Louisiana coast since 1966. The relationships between various abundance indexes and commercial harvest of age-I fish were determined by correlation and linear regression analyses. Several indexes were significantly correlated at the 0.95 and 0.99 level with commercial harvest. The strongest indexes, involving frequency of occurrence of more than 25 or 50 gulf menhaden in samples, were used to predict commercial landings. Recommendations were made to continue monitoring the...

Appraisal Of Otter Trawl Tow Lengths And Replicate Sampling

This study was conducted to determine the effects of otter trawl tow length on variahility and catch rates, and to assess replicate sampling. Longer tows caught more individuals/minute, individuals/tow, and species/tow than the shorter tows. The total number of species caught per hour of sampling, however, were essentially equal for all tow lengths. No difference in precision hetween tow lengths were detected. The numher of replicates needed to detect changes within desirahle statistical limits were logistically impractical. We recommend that otter trawls he used strictly for qualitative...

Analysis Of Prey Selection In Chain Pickerel

Chain pickerel (Esox niger) in Lake Conway consumed progressively more fish with increase in size. A shift also occurred in size, species composition, and relative abundance of fish prey with chain pickerel size. An index of selection was applied to food habit data. There was an increase in number of species and an increase in size of species that were positively selected as chain pickerel size increased. Size, rather than abundance of forage fish was the dominant influence on prey selection.

Endangered Freshwater Fishes Of The Southeastern United States

Endangered native freshwater fishes are catalogued for 16 southeastern states. The status of each of the 356 species is included at the nationaL regionaL or state levels. A standardized list of categories (endangered; threatened; special concern - national; special concern - state; extirpated) and definitions are suggested for use in state programs. Further recommendations are made to base programs on the state level on sound and manageable endangered species checklists.