Injury and Mortality Induced by Four Hook Types on Bluegill and Pumpkinseed

Abstract

Tackle manufacturers have responded to concerns regarding hooking injury and mortality by attempting to design and market hooks that are less damaging to fish (e.g., circle hooks). To date, studies investigating circle hooks have been primarily restricted to large marine species. We compared the injury and short-term (72-h) mortality of bluegills Lepomis macrochirus and pumpkinseeds L. gibbosus angled using number-6 circle hooks and three other conventional hook types (aberdeen, wide-gap, and baitholder) across three water temperatures (18, 22, and 26°C). Unlike other hook types, circle hooks were never lodged in the gullet, but they were frequently lodged in the eye. Some fish captured on conventional hooks were hooked deeply in the gullet, necessitating line cutting for release. Incidences of bleeding were low using all hook types, and when not lodged in the gullet, all hooks were generally easy to remove. Anatomical hooking locations differed among small (<145-mm) and large (>145-mm) bluegills for all hook types but not among pumpkinseeds. Hooking depth differed between small and large fish of both species captured on circle hooks; smaller fish were hooked more deeply. Mortality in both species was negligible at all water temperatures except for bluegills at 26°C (3% mortality). Bluegills that died were smaller than those that survived. Our results confirm the supposition that circle hooks are less susceptible to deeply hooking fish in the gullet. However, circle hooks permanently impaired vision of up to 22% of the fish, much more than for other hooks types. Although efficient at minimizing injury and mortality in marine fish, our study suggests that circle hooks perform similarly to more conventional hook types in fisheries for small sunfish.