Unanswered Forum Topics

The Pacific hake (Merluccius productus) midwater trawl fishery is the largest groundfish fishery off the U.S. West Coast by volume. However, bycatch of Chinook salmon can be an issue as Endangered Species Act (ESA)-listed Evolutionarily Significant Units represent a portion of the total Chinook salmon bycatch. This study investigated the influence of artificial illumination on Chinook salmon behavior and their escapement out of a bycatch reduction device (BRD) in a Pacific hake midwater trawl.

In the Mediterranean Sea, trawl nets have high levels of bycatch of protected species, including the loggerhead turtle (Caretta caretta), with high rates of mortality. A new flexible Turtle Excluder Device (TED) was tested for the first time on a commercial scale in the Mediterranean Sea to assess its effectiveness in reducing bycatch. The results did not show any significant (α = 0.05) loss in terms of commercial catch weight, but resulted in a significant reduction of debris in the codend of the nets in comparison to traditional nets.

To improve bycatch mitigation of chondrichthyans, reptiles and cetaceans for a tropical demersal fish-trawl fishery, species-specific responses to bycatch reduction devices (BRDs) were investigated using both in situ subsurface and onboard observations.

The study tested the use of a modified turtle exluder device (TED) - using substantially reduced grill spacing - in order to reduce elasmobranch bycatch in the Guyanese seabob shrimp fishery. The use of the modified TED resulted in a significant reduction (by 40%) of the bycatch rate of elasmobranchs. The TED also was highly effective in reducing the capture of three "Near Threatened" ray species.

The study quantified the impact of turtle excluder devices (TEDs) on the catches of various elasmobranchs caught off northern Australia using data collected during a previous study (Brewer, et al., 2006). The effect of fish size and various aspects of TED design such as grid orientation, grid angle, and bar space were quantified to determine their effect on the escape of elasmobranchs from shrimp trawls. The relatively low number of elasmobranchs encountered during sampling resulted in a lack of power to isolate the effects of the various factors tested.

The attractiveness of nine “bait” types were assessed ex situ on twelve wild-captured male diamondback terrapins in a commercial blue crab (Callinectes sapidus) pot fishery : no bait, chicken, shrimp, freshwater fish, presence of one female terrapin, presence of two female terrapins, presence of one male terrapin, presence of two male terrapins, and presence of one male terrapin and one female terrapin.