Anatomical hooking location and bleeding occurrence in northern pike (Esox lucius) caught in recreational catch-and-release angling in a lake with reduced prey fish availability

Abstract

Catch-and-release (C&R) is a common practice in recreational angling for northern pike (Esox lucius), whereby the angler releases the fish back into the water after capture with the expectation that it will survive with negligible stress and physical injuries. This may not always be the case, as hooking in critical anatomical locations, such as gills, esophagus, and stomach, increases the frequency of bleeding at the hook wound and has been recognized as a key determinant of post-release mortality in pike. Several factors (e.g. bait type and size, hook characteristics, and fish length) can influence the risk of hooking in critical locations, and the fish’s willingness to strike the fishing lure/bait may largely depend on previous feeding history and associated motivation to feed. In this respect, food deprivation and greater feeding motivation can be expected to result in an intensified response and more forceful attacks on fishing lures/baits, which could increase the risk of hooking injuries in sensitive tissues, as the fish may ingest the hook more deeply. Here, we assess the hooking location and bleeding occurrence in pike caught on soft plastic shads and baitfish in a shallow eutrophic lake. The prey fish density of this lake, primarily common roach (Rutilus rutilus), has been substantially reduced by seining as part of a lake restoration project. Experimental angling sessions took place at the end of 2020 and 2022, approximately 1–2 months and 25–26 months after the initial reduction in prey fish density, respectively. Removal of roach from the lake was also done regularly by seining after the angling sessions in 2020. Pike angled in 2022 had significantly lower body condition than individuals caught in 2020, indicating that mass removal of roach from the lake resulted in food shortage. The risk of hooking in critical locations (herein defined as hooking in gills and back of mouth) was not associated to angling year, body condition, or length of the pike. However, across the two angling years, the incidence of hooking in critical locations was higher for soft plastic shads compared to baitfish (24.2% versus 7.4%). Pike caught on soft plastic shads also bled more frequently than individuals caught on baitfish (19.7% versus 6.2%), most likely due to the fact that hooking in the gills almost exclusively occurred with soft plastic shads. Bleeding propensity was also not related to angling year, body condition, or fish length. Hence, the present study found no evidence that long-term reductions in food availability and resulting declines in body condition influence how pike strike and ingest fishing lures/baits, at least not in a manner that increases the risk of hooking injuries in sensitive locations. Instead, bait type seems to play the largest role for the observed bleeding patterns. We recommend that future studies investigate the potential effects of C&R angling on the post-release survival of pike with reduced body condition due to limited food availability.