- Carleton University
- Deakin University, Victoria, Australia
Despite a growing body of literature on the impacts of recreational fisheries on wild populations, surprisingly little is known regarding how individual differences in fish behaviour and their interaction with a baited hook influences hooking injury. We used an underwater video camera, fixed to the fishing line, to record the behaviour of wild sunfishes (Lepomis spp.) as they approached and attacked one of four treatments of baited hook used under a passive angling scenario. Angler reaction time was measured as the difference between the fish strike and hook set. Length-corrected hooking depth was evaluated as a function of multiple putative explanatory variables. Angler performance (hooksets/min) varied over the two day study, where hooksets/min decreased with small hooks and increased with large hooks. Model selection and model averaging revealed the top models included the terms: angler reaction time, approach to bait (cautious, deliberate, aggressive), hook size (small or large), and the interaction between approach to bait and hook size. The model-averaged fitted values indicated that length-corrected hooking depth increased most dramatically with angler reaction time when fish aggressively attacked a baited hook. A cautious approach to a large baited hook led to a deeper length-corrected hooking depth than a similar approach to a small baited hook. These results illustrate synergistic and interactive relationships among factors known to influence impairment, injury, and mortality in caught and released fish. Of particular novelty was our ability to assess the variation in how fish behaviour influences injury in a catch-and-release fishery using underwater cameras, which suggests that this approach holds promise in fisheries science.
Study site and sample collection
The study was performed at the Queen’s University Biological Station on Lake Opinicon in the Rideau Lakes area of Eastern Ontario (44° 34′N, 76° 19′W). Angling took place between approximately 14:00 to 16:00 h on 7 May and 8 May 2015. Lake Opinicon is shallow (<10 m deep), mesotrophic, and contains a diverse fish community including but not limited to largemouth bass (Micropterus salmoides), northern pike (Esox lucius) and two species of sunfish [Pumpkinseed, Lepomis gibbosus (Ps) and Bluegill, Lepomis macrochirus (Bg)]. Two novice participants (i.e., no previous angling experience) were employed to angle over the brief span of days. Participants were selected based on their similar lack of angling experience whereas the brief span of days helped reduce confounding influences of increasing water temperatures during the spring sampling period. Each of the two participants were outfitted with a medium action rod (198 cm) and reel, light-weight monofilament line (3.5 kg), and a Water Wolf underwater camera (Svendsen Sport, Gadstrup, Denmark). Cameras were tied between the main line and a leader that was approximately 60 cm long from the camera lens to the baited hook. A weight near the lens of the camera ensured it was oriented vertically and faced toward the baited hooks below (Fig. 1A, B). A small bobber was attached above the camera to provide additional buoyancy (Fig. 1B). Cameras were optimized for low-light conditions and able to internally record a series of 20-min videos for up to four hours (12 video files × 20 min/video file; resolution: 720 p).
From the camera it was possible to assess fish behaviour such as the approach and post-strike movement. Fish approach and attack was categorized as cautious (no clear forward motion with only buccal cavity suction to engulf the bait), deliberate (slow forward motion [approx. ≤1 body length s−1] and buccal cavity suction), and aggressive (rapid forward motion [approx. >1 body length s−1] to engulf the bait). During passive angling of sunfish, post-strike behaviour prior to hook setting usually involved rapid pivoting (e.g., a unidirectional head shake and 45° turn) with little lateral movement. As this was a common behaviour among angled sunfishes, post-strike and pre-hook set fish behaviour was assessed as the number of these movements. All research activities were conducted in accordance with guidelines from the Canadian Council on Animal Care at Carleton University, and under a scientific collection permit obtained from the Ontario Ministry of Natural Resources and Forestry (License no. 1079391).