The Consortium's research on barium sulfate gillnets to reduce bycatch of Brazil's endangered franciscana dolphin was featured in the Brazilian newspaper O GLOBO, "Novo tipo de rede promete ajudar a proteger toninhas"
Bycatch in gillnets is a serious threat to the franciscana dolphin (Pontopoia blainvillei), Brazil's most endangered dolphin. Gillnets are virtually invisible barriers for these dolphins, who frequently get trapped and drown in them.
Analyses of the Hawaiian pelagic longline fishery were conducted to determine what factors, including hook type (J or circle) and location (sea mount v open ocean), have impacted the catch of both target and bycatch species. Standardized catch rates for all tuna species as well as for blue and oceanic whitetip sharks were significantly higher when the wider circle hooks were used. However, shortbill spearfish and striped marlin catch were significantly lower when circle hooks were used.
Experiments were conducted aboard Korean pelagic longline vessels to determine if there were differences in the catch rates of target (tuna and billfish) and bycatch (sharks and other bony fish) species between 3 types of hooks; 4.0 traditional tuna hook (J-4), size 15 circle hook (C15) and size 18 circle hook (C18). Within the target group significant differences between catch rates were only found between the J-4 and C18 hooks. In the bycatch species group, significant differences were found between J4 and C15 and between J4 and C18. Overall, the large circle hook (C18)
A structured literature review of 103 papers was conducted to characterize trends in shark bycatch research. Gear modifications, such as hook size/type and net size, were the most commonly evaluated technique to reduce shark bycatch. Early studies tended to focus on trawl fisheries while more current studies focus on longline fisheries, particularly tuna fisheries. Overall, longline fishery studies made up the majority (44.6%) of published papers and typically were aimed at reducing bycatch. Later studies also tended to explore potential solutions to bycatch issues.
Two types of excluder devices, one with exclusion bars and one with exclusion rings, were fitted at the entrance to fyke nets to determine their efficiency in reducing turtle bycatch. In addition, the efficacy of an escape chimney, compared to a net with a large hole, was tested. The exclusion device with bars across the net significantly reduced turtle catch rates. Fish catch rates were not impacted by either excluder device. All turtles were able to escape through the escape chimney, while the majority of fish (88%) were retained.
During the period 1998-2001, a survey to study the incidence of the drifting longline fishery on shark populations was carried out in the eastern Mediterranean Sea. A total of 8 different pelagic shark species were recorded in the catches of the Greek swordfish and albacore longline fisheries. Among them, the blue shark, Prionace glauca, was the most common species in the catches while the bigeyed sixgill shark, Hexanchus nakamurai, was reported for the first time in the area.