Fishing gear modifications to reduce elasmobranch mortality in pelagic and bottom longline fisheries off Northeast Brazil

Afonso, A., Hazin, F., Carvalho, F., Pacheco, J., Hazin, H., Kerstetter, D., Murie, D., Burgess, G.
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Fisheries Research
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The type (circle 18/0 0 degree offset and J-style 9/0 10 degree offset) and position of hooks in the water column were tested to determine the effects on catch rates and mortality of elasmobranchs.  Tests were conducted aboard pelagic and bottom longline vessels. CPUEs for blue, silky and oceanic whitetip sharks were significantly higher with circle hooks than with J-style hooks. Silky, blue and oceanic whitetip sharks had a significantly higher mortality at haulback with J-style hooks.  Significant differences in hooking location between the two hook types was found for night, blue, silky and oceanic whitetip sharks. These sharks were more commonly hooked externally vs internally.  No significant differences between hook types was found for the CPUE's on bottom longlines.  Significantly more blacknose were alive at haulback when circle hooks were used on bottom longlines. Bottom longlines were also used to test for differences in CPUE by fishing depth.  Demersal hooks had significantly higher CPUE's than those suspended in the water column for blacknose and nurse sharks and southern stingrays.