Bottom Longline Survey Data

The Southeast Fisheries Science Center Mississippi Laboratories conducts standardized fisheries independent resource surveys in the Gulf of Mexico, South Atlantic, and U.S. Caribbean to provide abundance and distribution information to support regional and international stock assessments. A shark/snapper/grouper bottom longline survey is conducted every year from July through September. The survey covers waters between 5-200 fm from Cape Hatteras, North Carolina to West Palm Beach, FL, and the U.S. northern Gulf of Mexico from southwest Florida to Brownsville, TX. While there have been minor changes in gear and survey design, in general, during each survey approximately 300 randomly selected stations are sampled in both state and federal waters. Survey sites for bottom longline effort were selected at random within three depth strata: 9 – 55 m, 55 – 183 m, and 183 – 366 m in the Gulf of Mexico only. Most bottom longline sets are conducted parallel to depth contours unless survey conditions (i.e., current, sea state, wind) necessitated a different orientation. The number of randomly selected survey sites occupied within 60 nm contiguous sampling zones is proportionally allocated based on the amount of continental shelf area within each of the depth strata. In the Atlantic, 60% of stations were allocated between 9 - 55 m and 40% between 55 -183 m. In the Gulf of Mexico, 50% of stations were allocated between 9 - 55 m, 40% between 55 - 183 m, and 10% were allocated between 183 - 366 m (or at least 1 per sampling zone). Standardized gear utilized during the survey includes one mile of mainline and 100 15/0 circle hooks baited with Atlantic mackerel. Soak times are limited to one-hour to minimize mortality rates of all captured organisms and sampling occurs during day and night. All live sharks are tagged and released unless biological samples are needed for life history studies. Life history data pertaining to age, growth and reproduction are obtained from all captured reef fishes. All other fishes are measured and weighed prior to being released.

To provide abundance and distribution information on sharks and red snapper for use in regional stock assessments.

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As specimens are collected, total number of individual fish by species and lengths are taken and recorded into the shipboard data collections system. At the end of each survey data are reviewed for accuracy/relevance by chief scientists. Specimens that cannot be identified during the survey are identified in the laboratory.