Can circle hook use benefit billfishes?

Abstract

We performed a quantitative review to evaluate circle hook use in recreational and commercial hook-and-line fisheries that interact with billfishes (Family: Istiophoridae). Specifically, we scrutinized the findings of 11 recent empirical studies that reported, on a species-specific basis, side-by-side measures of circle vs. J-hook fishing performance: catch, mortality, deep-hooking and bleeding rates. Of the 30 total comparisons extracted from the literature that satisfied our inclusion criteria, 13 indicated significant differences between hook types for the specific metric compared. No study reported significant billfish catch rate differences between hook types. However, when significant differences between hook types were found, higher mortality rates and higher rates of deep-hooking and bleeding were associated with J-hooks relative to circle hooks. We conclude that empirical evidence is sufficient to promote circle hook use in almost all hook-and-line fishery sectors that typically interact with istiophorids. However, billfish conservation benefits will only be realized if fishers use unmodified circle hooks, commit to releasing live fish and take other appropriate measures which maximize post-release survival. While there may be fishing modes where circle hook effects are negative, for billfish conservation, we recommend managers grant exceptions to circle hook use only when experimental results support such a practice.

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

“…Tuna and teracima hooks have a slightly curved shaft, and like J-hooks, the shaft does not protect the point, and as a result, are categorized as 'J-shaped' hooks ( Fig. 1) (Beverly and Chapman 2007;Serafy et al 2009). Circle hooks are circular or oval shaped, and the point is turned perpendicularly back toward the shank, making the point less exposed relative to J-shaped hooks.…”

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

“…Circle hooks in 28 studies of marine recreational fisheries indicated an overall tendency for lower mortality, as circle-hooked fish were more frequently jaw-hooked than deep-hooked (Cooke and Suski, 2004). A quantitative review (Serafy et al, 2009) of 11 istiophorid studies of circle and J-hook performance in recreational rod-and-reel and commercial longline fisheries provided 30 species-specific comparisons, with 13 statistically significant differences between hook types. No significant differences in catch rates were evident for 4 billfishes (striped, white, blue marlin and sailfish) among 9 comparisons.…”

“…1; Cooke and Suski, 2004;Serafy et al, 2009). Circle hooks have been promoted in swordfish longline fisheries (Watson et al, 2005;Gilman et al, 2007; see review by Read, 2007) because of these hooks' potential to reduce sea turtle interaction rates, and they have a higher frequency of mouth hooking vs. deep hooking for sea turtles and fishes, which may reduce post-release mortality.…”

“…Two meta-analyses (Cooke and Suski, 2004;Serafy et al, 2009) summarized the performance of circle hooks and J-hooks regarding capture efficiency, mortality rate and injury caused by hooking and bleeding. Circle hooks in 28 studies of marine recreational fisheries indicated an overall tendency for lower mortality, as circle-hooked fish were more frequently jaw-hooked than deep-hooked (Cooke and Suski, 2004).…”

Effects of Hook and Bait on Targeted and Bycatch Fishes in an Equatorial Atlantic Pelagic Longline Fishery

“…;soykan et al 2008). although longlines are more selective than other fishing gears (e.g., trawls), drifting pelagic longlines catch a wide variety of bycatch, the unintended non-target organisms that are captured during fishing operations (lewison et al 2004).…”