One of the primary factors associated with mortality in catch-and-release recreational fisheries is depth of hook position relative to the snout, with deeper hooking locations (i.e., gullet) increasing risk of injury to vital tissues. As a result, there have been attempts to develop angling methods and gear that are less likely to result in deep hooking. Circle hooks represent an alternative to conventional “J” style hooks (J-hooks), and in general circle hooks have been shown to reduce the tendency for deep hooking in a variety of species, which can significantly improve post-release survival. Relative to fishing with J-hooks, circle hook manufacturers typically recommend that anglers use a rod movement (i.e., hook-set) of reduced intensity and force (i.e., a light hook-set), thereby maximizing the benefit of circle hooks by reducing the tendency for deep hooking and injury. To evaluate whether hook-set technique can affect hooking and injury in fish, we tested different combinations of hooks (circle hooks and J-hooks) and hook-set techniques (e.g., light, moderate, or heavy force, or with a bobber) in an angling study for bluegill (Lepomis macrochirus) in Lake Opinicon, Ontario, Canada. Binary responses of capture success and deep hooking were analysed with logistic regression. There was no significant interaction between hook type and hook-set, but overall, J-hooks increased the odds of successfully capturing a bluegill and also the odds of deep hooking a bluegill relative to circle hooks. The bobber hook-set technique increased the odds of deep hooking a bluegill relative to the active hook-setting techniques. This study suggests both deep hooking and capture of bluegill are significantly affected by both hook types and hook-set techniques.
Data were collected at Lake Opinicon, a shallow mesotrophic lake in Eastern Ontario, Canada. Angling was conducted from July 17 to July 26, 2012, from floating docks at the Queens University Biological Station and from a boat. Fishing from a drifting boat can confound hook-setting angle and velocity (Zimmerman and Bochenek, 2002), so when fishing from the boat it was anchored to prevent trolling. Anglers fished with identical 6′ medium action Rapala fishing kits with monofilament line and drag settings on the reel maximized so that it did not influence the hook-set. Two individuals participated in the angling, one of whom captured the majority of fish. Generic, commercially available size 12 circle hooks were used and matched with a J-hook of similar length (No. 8 Eagle Claw L181G-8 Lazer Sharp) because there is lack of an industry-wide sizing standard between circle hooks and J-hooks (Serafy et al., 2012). Both hooks were offset (i.e., point shank and main shank are not parallel) by the manufacturer, but the offset was corrected prior to angling because offset hooks are considered more injurious to fish (Bartholomew and Bohnsack, 2005, Cooke and Suski, 2004, Sullivan et al., 2012). A single split shot weight was attached to the line approximately 30 cm above the hook for all treatments, which helped to lower the bait into the water column to the depth frequented by fish. Hooks were baited with small pieces of live earthworms, which are commonly used as bait by novice and experienced bluegill anglers (Cooke et al., 2003). For the passive treatment with a bobber, a pencil bobber was used to suspend the bait motionless in the water column (Table 1 summarizes treatments). Whereas all other treatments were used with an active retrieve of the bait, the bobber was a completely passive treatment in which there was no movement of the bait or tension of the line when the fish ingested the hook.