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- Progress on a meta-analysis for comparing hook, bait and leader effects on target, bycatch and vulnerable fauna interactionsPublication . Casaca Santos, Catarina; Rosa, Daniela; Coelho, RuiThis paper describes the progress of an EU Project "Evaluation of the effects of hooks’ shape & size on the catchability, yields and mortality of target and by-catch species, in the Atlantic Ocean and adjacent seas surface longline fisheries". At this stage, a meta-analysis of 36 publications totaling 55 experiments was conducted to assess effects of hook, bait, and leader type on retention and at-haulback mortality rates of swordfish, blue shark, and loggerhead sea-turtle. Using circle hooks significantly lowers retention rates of loggerhead sea-turtles and swordfish. Fish bait significantly reduces the retention of loggerhead sea-turtles but does not significantly affect the retention of swordfish or blue shark. The effects of using wire leaders could not be assessed for the loggerhead turtle and significantly increased retention of blue sharks. As for at-haulback mortality, it was significantly reduced for swordfish when using circle hooks. Fish bait increased at-haulback mortality of blue shark and was not significant for the other taxa. The effects of using wire leaders on at-haulback mortality were only possible to calculate for blue shark and were not significant.
- Hook, bait and leader type effects on surface pelagic longline retention and mortality rates: a meta-analysis with comparisons for target, bycatch and vulnerable fauna interactionsPublication . Casaca Santos, Catarina; Rosa, Daniela; Coelho, RuiA meta-analysis of 24 publications was conducted to assess effects of hook, bait and leader type on retention and at-haulback mortality rates of target, bycatch and vulnerable species of the pelagic longline fishery. Turtles and swordfish had lower retention rates with circle hooks. In contrast, retention rates of 3 sharks and 2 tuna species were greater with circle hooks. Bait type did not seem to significantly influence the retention rates of most of the species examined. Wire leader lead to a decrease in retention rates of bony fishes and a mix for elasmobranchs. For athaulback mortality, hook type was the most influential, with 5 elasmobranch species and 6 bony fishes having a significantly lower at-haulback mortality rates when using circle hooks. Bait type and leader type did not have a significant effect on at-haulback mortality rates for most species. The results presented here should be considered preliminary. Future work will consider expanded information on fishery characteristics.
- Assessing the effects of hook, bait and leader type as potential mitigation measures to reduce bycatch and mortality rates of shortfin mako: a meta-analysis with comparisons for target, bycatch and vulnerable fauna interactionsPublication . Rosa, Daniela; Casaca Santos, Catarina; Coelho, RuiA meta-analysis of 24 publications was conducted to assess effects of hook, bait and leader type on retention rates of target, bycatch and vulnerable species of the pelagic longline fishery. Retention rate and at-haulback mortality rate analyses considered hook type, bait type, the combination of both variables and leader type. Turtles and swordfish had a lower retention rate with circle hooks. In contrast, retention rates of 3 sharks and 2 tuna species were greater with circle hooks. Bait type alone did not seem to significantly influence the retention rates of most of the species examined. Results were mixed when considering the combined effects of hook and bait type. Wire leader led to a decrease in retention rates of bony fishes and a mix for elasmobranchs. For at-haulback mortality, hook type was the most influential, while bait type only influenced blue shark at-haulback mortality. Leader type did not have a significant effect. The results presented here should be considered preliminary. Future work will consider information on at-haulback mortality rates for bony fishes and sea turtle and expanded information on fishery characteristics.