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. 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.

Coastal shark community structure was quantified across 10 geographic areas in the northeastern Gulf of Mexico using fishery-independent gillnet data from 2003-2011. A total of 3,205 sets were made in which 14,244 carcharhiniform sharks, primarily juveniles, were caught comprising 11 species from three families. Atlantic sharpnose sharks (Rhizoprionodon terraenovae) were the most abundant species overall followed by bonnethead (Sphyrna tiburo) and blacktip sharks (Carcharhinus limbatus). Two-way crossed analysis of similarity (ANOSIM) found geographic area to significantly influence shark species-life stage assemblages while season did not. Resemblance matrices between environmental data and shark community assemblage found the two were significantly correlated with the combination of salinity and turbidity producing the highest spearman rank correlation value. Species diversity varied by geographic area, but was generally highest in areas with the greatest amount of fresh and saltwater fluctuations. The mean size of the three most abundant species differed across geographic areas whereas, those species in lower abundances also differed across regions, but exhibited no discernible pattern. Our results suggest geographic area is important for juvenile sharks and some areas may be considered important nursery areas for many species. Atlantic sharpnose and blacktip shark were not restricted to any specific geographic area but species such as bull (C. leucas), spinner (C. brevipinna), blacknose (C. acronotus), finetooth (C. isodon), sandbar (C. plumbeus) and scalloped hammerhead (S. lewini) sharks were only consistently captured within a single area or over a select group of areas.

Data is available from annual bottom longline surveys conducted cooperatively by Japan (1979-1994) and the U.S. National Marine Fisheries Service, Alaska Fisheries Science Center (1988-present). Starting in 1988, the U.S. started conducting the survey, creating overlap between the two countries between1988-1994. Since 1994, the U.S. has conducted the survey independently. Stations are spaced systematically (~20-30 km apart) along the slope from the eastern Gulf of Alaska west to the Aleutian Islands and north into the eastern Bering Sea. At each station, depths from ~150-1000 meters are sampled. Each year the captain attempts to set the gear along the same path. The same stations are sampled each year except in the Aleutian Islands and the Bering Sea, which are sampled every other year at the beginning of the survey (last week of May-early June). Since 1995, in odd years the Bering Sea stations are sampled and in even years the Aleutian Islands are sampled. The status of each hook is recorded. Lengths are taken from major species including, sablefish, giant grenadier, Pacific grenadier, Greenland turbot, arrowtooth flounder, Pacific cod, shortspine thornyhead, and all rockfish caught.

This data set contains catch and effort, landings, and observer data from longline vessels fishing in the North Pacific outside the U.S. west coast EEZ. Logbooks and landings data are available from 1991 to the present and observer data is available from 2001 to present. California-based longliners target swordfish and bigeye tunas, however, other species of tunas, billfishes, and sharks are also caught.

Reproductive data from Atlantic sharpnose sharks were collected from specimens captured throughout the northern Gulf of Mexico on various research vessels. Data included those necessary to describe the size at maturity, reproductive cycle, mating period, gestation time and fecundity of the species.

Photos of catch, methodology, scientists, and habitat organized by year and month, 2003-current.

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An experimental bottom longline survey was conducted at depths >1,000 m in the western Gulf of Alaska in August 2008. The objective was to investigate the abundance and biological characteristics of giant grenadier (Albatrossia pectoralis) and sablefish (Anoplopoma fimbria) in deep waters of the Gulf of Alaska that have not been previously sampled in fishery surveys. Several difficulties were encountered during the fishing operations which indicate special problems may occur when fishing longlines at these depths, including substantial gear drift after setting and hang-ups on the bottom that caused the longline to part. Although results were not conclusive because only stations in the western Gulf of Alaska were sampled, there was consistency in the results which provides an indication of fish abundance and distribution in depths >1,000 m. Catch rates of giant grenadier were relatively high, although not as large as those in nearby longline survey stations in depths <1,000 m. Female giant grenadier were much larger in size at the deep-water stations, and their weight averaged 69% greater than females at depths <1,000 m. Males, which comprise a low percentage of the catch in shallower water, were caught in much higher numbers at the deep-water stations. Catch rates for sablefish at the deep-water stations were extremely low, and it appears abundance of sablefish is negligible in the western Gulf of Alaska at depths >1,000 m. Besides giant grenadier, Pacific grenadier (Coryphaenoides acrolepis) was the only other species caught in substantial numbers. At one deep-water station, Pacific grenadier were extremely abundant and were caught on 56% of the longlines hooks.

The Gulf of Mexico Shark Pupping and Nursery (GULFSPAN) survey is a fishery-independent survey that began in 1994 to examine the distribution and abundance of juvenile sharks in coastal areas of the Gulf of Mexico. The data describes coastal shark abundance and environmental data from St. Andrews Bay to Apalachicola Bay in the northeastern Gulf of Mexico.

The Southeast Fisheries Science Center Mississippi Laboratories conducts standardized fisheries independent resource surveys in the Gulf of Mexico to provide abundance and distribution information to support regional and international stock assessments. A pilot pelagic longline survey was conducted in 2005 in the northern Gulf of Mexico. The objective of the survey was to examine the feasibility of using pelagic longline gear to collect fisheries independent data on stocks of offshore fishes and to establish protocols for future use of data. Additional objectives included examining the distribution and relative abundance of pelagic fishes in the region and to collect biological and environmental data.