Daniel G. Foster

The Behavioral Response of Juvenile Red Snapper ( Lutjanus campechanus ) to Shrimp Trawls that Utilize Water Flow Modifications to Induce Escapement

Clear differences in swimming ability between finfish and shrimp in trawls have been utilized in the Southeastern U.S shrimp fishery to reduce the bycatch of finfish. The Jones/Davis device which has been mandated for use in the Gulf of Mexico shrimp fishery uses four windows to provide an escape path for fish while a funnel keeps the shrimp away from the windows, reduces water flow around the windows, and acts as a leading panel to guide the fish out of the trawl. Observations of fish behavior showed thatfinfish generally reacted to the slack water flow created by the funnel by swimming towards the lowest water flow area. The escape rate of finfish such as juvenile red snapper (Lutjanus campechanus), however, was low and random during towing when no net surging and fish crowding occurred. The highest escape rates occurred during slow down prior to haulback, but were dependent on the haul back procedure. This may help explain the haul-to-haul variation in escapement documented for the Jones/Davis device. Modifications and techniques to improve escape rates during towing are discussed.

The development of bycatch reduction technology in the Southeastern United States shrimp fishery

Shrimp trawl bycatch is a significant source of fishery induced mortality for managed species including red snapper (Lutjanus campechanus Poey), Spanish mackerel (Scomberomorus maculatus Mitchell), and weakfish (Cynoscion regalis Baloch, Schneider) in the southeastern United States. These species have been overfished and are under both state and federal management plans which include regulations mandating reduction of shrimp trawl bycatch mortality. In 1990 the U.S. Congress passed amendments to the Magnuson Fishery Conservation and Management Act (16 U.S.C. 1854) which called for a research program that included the design and evaluation of approaches for reducing shrimp trawl bycatch mortality. A strategic planning initiative addressing finfish bycatch in the Gulf of Mexico and southeastern Atlantic shrimp fisheries was developed by the Gulf and South Atlantic Fisheries Foundation through funding and guidance provided by the National Marine Fisheries Service. A cooperative research plan was developed in 1992 which included the identification, development, and evaluation of gear options for reducing bycatch in the Gulf of Mexico and southeastern Atlantic shrimp fisheries. Between 1990 and 1996 one hundred and forty five bycatch reduction conceptual gear designs contributed by fishers, net shops, gear technicians, and biologists were evaluated. Sixteen of these designs were tested on cooperative commercial shrimp vessels by observers under the southeast regional cooperative bycatch program. Analyses of data from commercial vessel testing indicates that two bycatch reduction designs have potential to significantly reduce shrimp trawl bycatch for weakfish and Spanish mackerel in the southeastern Atlantic and two designs have the potential to significantly reduce red snapper bycatch in the Gulf of Mexico. The fisheye and the extended funnel bycatch reduction devices have been mandated for use in the southeastern Atlantic shrimp fishery and the fisheye and Jones/Davis bycatch reduction devices have been mandated for use in the Gulf of Mexico shrimp trawl fishery.

Time, temperature, and depth profiles for a Loggerhead Sea Turtle (Caretta caretta) captured with a pelagic longline.

Abstract During a pelagic longline pilot study conducted by the National Oceanic and Atmospheric Administration, National Marine Fisheries Service, Southeast Fisheries Science Center, Mississippi Laboratories along the US Atlantic Ocean coast (NOAA Ship OREGON II OT-06-02-269), a Caretta caretta (Loggerhead Sea Turtle) was captured with longline gear equipped with time-temperature-depth recorders attached in proximity to hooks. Time-temperature-depth data documented changes in hook depth and water temperature, and reflected behavior of the Loggerhead Sea Turtle (rates of descent and ascent, time at depth, time near surface). Sea turtle mortality mitigation recommendations for pelagic longline gear proved effective for this Loggerhead Sea Turtle capture since there were successive ascents to surface, and the viability status was good after landing.

The webbing reef: a tool used in the study of juvenile red snapper (Lutjanus campechanus)

The primary purpose for requiring shrimp trawlers to use bycatch reduction gear in the U.S. Gulf of Mexico is to reduce the incidental capture and mortality of juvenile red snapper (Lutjanus campechanus). Developing effective bycatch reduction devices (BRDs) for this purpose requires a good understanding of juvenile snapper behavior and their reaction to different trawl components, which is being accomplished through diver observations on shrimp trawls and with trawl attached cameras. Early BRD development was dependent on chance encounters with juvenile snapper, but that changed in the mid-1990s with the invention of the trawlable webbing reef. The webbing reef proved to be ideally suited for attracting and concentrating juvenile red snapper for BRD studies, and its design was perfected to the point that it is now a simple, easily deployed, self-anchoring system. From habitat studies, we learned that we could selectively attract either age-0 or age-1 snapper by adjusting reef height and applied this in the design of the latest webbing reef. In the process of studying BRD escapement and site fidelity, we determined that juvenile red snapper have homing capabilities. Young snapper were observed residing at a webbing reef for almost four months, and displaced snapper were able to return to their original habitat from a distance of almost 2 km. Our study on spatial and temporal recruitment patterns indicates greater recruitment and longer residence time on reefs off Mississippi than off Alabama or Florida. A major factor affecting recruitment off Mississippi in 2001 was the occurrence of hypoxia which caused the loss of all red snapper and most of the invertebrates on and around the reefs. While the webbing reef has been an invaluable tool for increasing our knowledge of juvenile red snapper, its use is not limited to snapper studies. The webbing reef attracts and provides habitat for other species of fish, invertebrates and plants and, because of its simplicity and portability, can be used for long or short term projects in almost any marine environment.

Sea Turtle Bycatch Mitigation in U.S. Longline Fisheries

Capture of sea turtles in longline fisheries has been implicated in population declines of loggerhead (Caretta caretta) and leatherback (Dermochelys coriacea) turtles. Since 2004, United States (U.S.) longline vessels targeting swordfish and tunas in the Pacific and regions in the Atlantic Ocean have operated under extensive fisheries regulations to reduce the capture and mortality of endangered and threatened sea turtles. We analyzed 20+ years of longline observer data from both ocean basins during periods before and after the regulations to assess the effectiveness of the regulations. Using generalized additive mixed models (GAMMs), we investigated relationships between the probability of expected turtle interactions and operational components such as fishing location, hook type, bait type, sea surface temperature, and use of light sticks. GAMMs identified a two to three-fold lower probability of expected capture of loggerhead and leatherback turtle bycatch in the Atlantic and Pacific when circle hooks are used (vs. J hook). Use of fish bait (vs. squid) was also found to significantly reduce the capture probability of loggerheads in both ocean basins, and for leatherbacks in the Atlantic only. Capture probabilities are lowest when using a combination of circle hook and fish bait. Influences of light sticks, hook depth, geographic location, and sea surface temperature are discussed specific to species and regions. Results confirmed that in two U.S.-managed longline fisheries, rates of sea turtle bycatch significantly declined after the regulations. In the Atlantic (all regions), rates declined by 40% and 61% for leatherback and loggerhead turtles, respectively, after the regulations. Within the NED area alone, where additional restrictions include a large circle hook (18/0) and limited use of squid bait, rates declined by 64% and 55% for leatherback and loggerhead turtles, respectively. Gains were even more pronounced for the Pacific shallow set fishery, where mean bycatch rates declined by 84% and 95%, for leatherback and loggerhead turtles, respectively, for the post-regulation period. Similar management approaches could be used within regional fisheries management organizations to reduce capture of sea turtles and to promote sustainable fisheries on a global scale.