Yield-Per-Recruit of Spotted Seatrout

A von Bertalanffy growth curve, L = 65.47 cm (1 - e-.2005 (t + .4113 yr)), is derived from published data on spotted seatrout in the U.S. Gulf of Mexico and used in constructing a yield-per-recruit contour. Maximum yield-per-recruit is approached as F increases above 1 and age of first entry approaches 3.9 years (14.9 in., 1.1 lb). A linear regression is derived relating average size of capture to gill net mesh size (MS in inches), L = 1.97 in. + 8.63 MS, and used along with legal sizes of first harvest to evaluate the impact of current laws in the Gulf states on yield-per-recruit of spotted seatrout

An Analysis of the Long-Term Salinity Patterns in the Louisiana Coastal Zone

Saltwater intrusion is believed to be one of the greatest threats to Louisiana\u27s fishery and wildlife resources. The Louisiana Department of Wildlife and Fisheries has maintained salinity recording stations throughout the state\u27s coastal marshes since the 1960\u27s. We applied several different analytical approaches to the salinity data from 17 stations to determine whether this data base could be used to detect and quantity long-term salinity trends in coastal Louisiana. We did not detect a large-scale, consistent trend over time in coastal salinities across the state. Problems that hindered the detection of long-term trends included short periods of record and the placement of the recording stations in salt and brackish marsh areas, where we would not expect to find great changes in salinity. For the data to be useful in monitoring salinity trends in coastal marshes, especially with respect to saltwater intrusion, stations should be added in fresh and intermediate marshes. In addition, the relationships our study revealed between short- and long-term data indicate that records covering less than a decade are insufficient to denote long-term salinity changes, barring some major modification of the hydrologic regime

Discovery, Evaluation, and Sand Mining Recommendations Based on Blue Crab, Shrimp, and Spotted Seatrout Findings

This study examines the how coastal erosion effects offshore shoals role as spawning/hatching/foraging grounds for shrimp and blue crabs

Yield-Per-Recruit of Spotted Seatrout

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Discovery, evaluation, and implications of blue crab, Callinectes sapidus, spawning, hatching, and foraging grounds in federal (us) waters offshore of Louisiana

Although blue crabs, Callinectes sapidus Rathbun, 1896, are ecologically important predators and support the world's most valuable crab fishery, little is known about their spawning and hatching migrations beyond the estuary. We discovered unexpectedly high concentrations of female blue crabs actively spawning, hatching their eggs, and foraging in federal waters within our study area, the Ship, Trinity, Tiger Shoal Complex (STTSC) >= 20 km off the Louisiana coast. During a three-year investigation, blue crab abundances were significantly higher on Ship and Trinity Shoals than the surrounding, muddy and deeper seafloor. Crabs from the STTSC compared favorably with those from nationally recognized spawning grounds in terms of condition factor (an index of health), fecundity, and abundance. Ninety percent of females possessed a sponge, large ovary, or both. Eighty-seven percent of non-ovigerous females showed evidence of a previous hatching. An analysis of ovarian development suggests that STTSC crabs produce new sponges approximately every 21 d, and at least seven broods per spawning season (similar to April-October). Monthly declines in sponge weight and a companion study of benthic macrofauna suggest fecundity may be limited by food supply in areas of high crab abundance. Symbionts did not negatively impact condition factor. Carapace width including the lateral spines was a much poorer estimator of crab weight than carapace width excluding the lateral spines, height, length, or estimated volume. Given the increasing national importance of the Louisiana blue crab fishery and declines elsewhere, we recommend that management safeguard these previously unknown spawning, hatching, and foraging grounds