Atlantic Croaker Abundance from SEAMAP Shrimp/Groundfish Surveys 1987-2009

The data presented here are summarized from Southeast Area Monitoring and Assessment Program (SEAMAP) Summer and Fall Shrimp/Groundfish Surveys. The Summer Shrimp/Groundfish Survey started collecting data in 1982 while the Fall Shrimp/Groundfish Survey started collecting data in 1985. The survey design of both surveys was standardized in 1987. Therefore, the data presented here are from 1987 to 2009. Since 1987, the strategy for the trawl surveys has been that day/night sampling sites are chosen randomly in areas stratified by depth and statistical area. Trawl stations sampled by NMFS, Florida, Alabama, Mississippi, and Louisiana are made with a standard SEAMAP 40-ft net, and Texas samples with a 20-ft net. Depth strata consist of 1-fm intervals from 5 to 20 fm, a 2-fm interval from 20 to 22 fm, a 3-fm interval from 22 to 25 fm, 5 fm intervals from 25 to 50 fm and a 10-fm interval from 50 to 60 fm. Trawls are towed perpendicularly to the depth contours and cover the entire depth stratum on each station. Single tows are for a maximum of 55 minutes; for certain stations, a series of consecutive trawl tows is necessary to cover a given depth stratum, with a minimum individual tow across each stratum of 10 minutes and a maximum tow of 55 minutes. The Texas vessels tow 10 minutes parallel to the depth stratum. The survey design was changed in 2009 for NMFS samples and 2010 for all other SEAMAP participants except Texas. With the new survey design, trawls are towed for 30 minutes regardless of whether a depth stratum is covered or not and stations are no longer stratified on whether they are taken during the day or night. Until 2008, Florida did not participate in the trawl surveys and trawl samples were not taken off Florida. In 2008, Florida began participating in the Summer and Fall Shrimp/Groundfish Surveys and NMFS began trawling off Florida. All species of fishes and invertebrates from trawls are identified, enumerated, and weighed. Weights and individual measurements on selected species other than commercial shrimp are also recorded. Total counts from each trawl station are standardized to account for sampling effort and converted to a catch per unit effort (CPUE). CPUE is expressed as the number of fish caught per 1 hour of tow time for a 40 ft trawl. Mean CPUE was then summarized by 10 minute longitude by latitude blocks in which trawling occurred. Since Texas vessels do not strictly adhere to the survey design, data from Texas were not used for this summary

Fishery-independent trawl data from Southeast Area Monitoring and Assessment Program (SEAMAP) Summer and Fall Shrimp/Groundfish Surveys (1987 - 2009) are used to map the distribution, abundance and occurrence of Atlantic croaker. Catches of Atlantic croaker are standardized to account for sampling effort (CPUE) and expressed as the number of fish per 1 hour tow. Mean CPUE is then summarized by 10 minute longitude by latitude blocks in which trawling occurred.

SEAMAP is a State/Federal/university program for collection, management and dissemination of fishery-independent data and information in the southeastern United States. Resource surveys began in the Gulf of Mexico in 1982. These surveys currently include Winter, Summer, and Fall Shrimp/Groundfish Surveys; Winter, Spring, and Fall Plankton Surveys; a Reeffish Survey; a Vertical Longline Survey; and an Inshore Bottom Longline Survey. These surveys collect a variety of biological and environmental information. All SEAMAP data are available upon request. For information concerning SEAMAP, please contact Jeff Rester of the Gulf States Marine Fisheries Commission at (228) 875-5912 or via e-mail at jrester@gsmfc.org.