Fishery Ecology Branch Recent Research

The alteration of essential fish habitat (structural components, benthic community structure, and ecosystem level processes) by fishing activities is not well understood, yet it is generally acknowledged that fishing can influence species composition and diversity of non-target organisms and reduce habitat complexity. Little research has been conducted on fishing gear impacts in the Gulf of Mexico, and information to predict the magnitude of these effects and to determine whether habitat alterations are short- or long-term is generally lacking. However, fishing has been shown to affect the structural components of habitat. Numerous studies outside the Gulf of Mexico indicate that mobile fishing gear reduces habitat complexity by: 1) directly removing epifauna or damaging epifauna leading to mortality, 2) smoothing sedimentary bedforms and reducing bottom roughness, and 3) removing taxa which produce structure (i.e., colonies, tubes, mounds, burrows, and pits). Overall, the recovery of habitat structure is difficult to predict as timing, duration, severity, seasonality, and frequency of impacts all interact and influence processes that lead to recovery.

The NOAA Fisheries Southeast Fisheries Science Center (SEFSC) has determined that trawls are among the fishing gears most likely to impact EFH in the Gulf of Mexico. The Gulf of Mexico shrimp trawl fishery is the largest, most geographically widespread fishery of any in the southeastern United States. It is also one of the most carefully and consistently documented in terms of catch, effort, and location. The shrimp fleet is the most likely fishery to exert short- and long-term effects, if any, on fish and shellfish habitat on the continental shelf.

Any examination of fishing gear impacts requires information on habitat distribution, animal abundance, and the intensity of disturbances. The objectives of this project were to 1) identify and obtain data bases describing continental shelf habitats, trawl fishery activities, and other human activities, 2) to incorporate these data sets into a geographical information system (GIS) format, and 3) to provide preliminary experimental designs for the assessment of the effects of shrimp trawling to EFH on the Gulf of Mexico continental shelf. The habitat data can also be used in the future to frame studies of other fishing gears, since traps, longlines, dredges, and recreational fishing have also been identified as fishing methods with high potential for impact. Habitat includes both substrates and benthic fauna that are utilized by bottom-dwelling organisms such as fishes, shrimps, and crabs for refuge, growth, feeding, or reproduction.