Effects of circle hooks on pelagic catches in the Hawaii-based tuna longline fishery

Curran, Daniel S.; Bigelow, Keith

doi:10.1016/j.fishres.2011.02.013

Cited by 49 publications

(62 citation statements)

References 25 publications

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“…The finding of reduced probability of sea turtle bycatch on circle hooks is consistent with a number of different studies and has been thoroughly discussed (Watson et al, 2005;Yokota et al, 2009;Curran and Bigelow, 2011;Santos et al, 2012;Serafy et al, 2012).…”

Section: Hook Typesupporting

confidence: 82%

“…Based on results of numerous investigations, there is general consensus that replacing squid bait with fish bait will reduce sea turtle bycatch. However, regulations requiring use of fish bait to reduce sea turtle bycatch must be balanced against the potential target species catch loss, a concern that has been previously evaluated (Watson et al, 2005;Yokota et al, 2009;Curran and Bigelow, 2011;Coelho et al, 2012). Further, bait choice can also potentially increase bycatch of certain sharks or other vulnerable species (Foster et al, 2012;Santos et al, 2012;Gilman et al, 2016b).…”

Section: The Role Of Bait In Bycatchmentioning

confidence: 99%

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Sea Turtle Bycatch Mitigation in U.S. Longline Fisheries

et al. 2017

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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.

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Section: Hook Typesupporting

confidence: 82%

Section: The Role Of Bait In Bycatchmentioning

confidence: 99%

Sea Turtle Bycatch Mitigation in U.S. Longline Fisheries

et al. 2017

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“…Horodysky and Graves, 2005). On the other hand, circle hooks have been also associated with higher catch rates of sharks (Watson et al, 2005;Yokota et al, 2006; but see Curran and Bigelow, 2011), which could compromise their effectiveness on bycatch mortality mitigation due to higher absolute mortality rates. However, heterogeneous catch rates between hook types could be ascribed to post-hooking processes, further complicating the association between hook types, catch rates, and mortality rates.…”

Section: Introductionmentioning

confidence: 99%

Shark bycatch and mortality and hook bite-offs in pelagic longlines: Interactions between hook types and leader materials

et al. 2012

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“…Hook minimum or narrowest width refers to the narrowest dimension of the hook (Fig. 2) (Curran and Bigelow 2011;Serafy et al 2012). Bait types were squid species (Illex sp.)…”

Section: Methodsmentioning

confidence: 99%

Review of effects of pelagic longline hook and bait type on sea turtle catch rate, anatomical hooking position and at-vessel mortality rate

Gilman

Huang

2016

Rev Fish Biol Fisheries

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Review of effects of pelagic longline hook and bait type on sea turtle catch rate, anatomical hooking position and at-vessel mortality rate WCPFC-SC13-2017/ EB-IP-01Gilman, E 1 . and H-W. Abstract Bycatch in pelagic longline fisheries is one of the most serious threats to some sea turtle populations. Hook shape, hook minimum width and bait type have been the focus of research and management measures to mitigate problematic bycatch of vulnerable taxa. To assess the current state of knowledge and progress over the past decade, we reviewed findings on the effects of hook and bait type on pelagic longline sea turtle catch rates, anatomical hooking position and at-vessel mortality. Fish versus squid for bait lowered catch rates of leatherback sea turtles (Dermochelys coriacea) and individual species of hard shelled turtles. Fish bait also reduced hard-shelled turtle deep hooking. Wider circle hooks reduced both leatherback and hard-shelled turtle catch rates relative to narrower J and tuna hooks, and reduced the proportion of caught hard-shelled turtles that were deeply hooked. Wider circle hooks with fish bait reduced leatherback and hard-shelled turtle catch rates relative to narrower J and tuna hooks with squid bait. Wider versus narrower circle hooks reduced hard-shelled sea turtle catch rates and deep hooking. The mechanisms for hook and bait type effects on turtle interactions are reviewed. Research designed to assess single factor effects is needed, in particular for hook shape and minimum width, and for hook and bait effects on anatomical hooking position and survival rates. Fishery-specific and holistic assessments are needed to account for variability between fisheries in a bycatch mitigation method's commercial viability, relative risks to affected populations and possible conflicting effects on vulnerable taxa.

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Effects of circle hooks on pelagic catches in the Hawaii-based tuna longline fishery

Cited by 49 publications

References 25 publications

Sea Turtle Bycatch Mitigation in U.S. Longline Fisheries

Sea Turtle Bycatch Mitigation in U.S. Longline Fisheries

Shark bycatch and mortality and hook bite-offs in pelagic longlines: Interactions between hook types and leader materials

Review of effects of pelagic longline hook and bait type on sea turtle catch rate, anatomical hooking position and at-vessel mortality rate

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