Influence of hook barbs on the through-the-gill hook removal method for deeply hooked Smallmouth Bass

Sustainable catch-and-release fisheries are based on the assumption that most fish survive an angling event. The adoption of best practices has become important to help mitigate post-release injury, behavioral impairment and mortality. However, in any catch-and-release fishery, a proportion of fish will become inadvertently deeply hooked (e.g., in the gullet) and numerous studies have shown this to be a major driver of mortality. Although available science suggests that cutting the line tends to yield better outcomes than removing hooks in the gullet, there has been interest within the angling community with removing hooks using the through-the-gill method where the hook shaft is turned outwards into the gill region and then the hook is removed by pulling anteriorly by gripping the outside bend of the hook. Here, we tested the efficacy of removing barbed and barbless hooks though the gill opening from experimentally deep-hooked Smallmouth Bass (Micropterus dolomieu) relative to leaving the hooks in place. Using a control group and four experimental treatment groups (barbed and removed through the gills; barbless and removed through gills; barbed and left in; barbless and left in), we evaluated handling time, presence of bleeding, incidence of gill or esophageal injury, reflex impairment, incidence of hook shedding (for the left in treatment groups), and survival across a 24-hour monitoring period. Collectively, our results suggested that when hooks were barbed and removed through the gills, fish condition and survival were lower. In addition, barbed hooks were more likely to cause bleeding, gill damage, esophageal tearing, and impair reflexes. When hook removal was done through the gills, the chances of all sublethal outcomes across all categories were more likely to occur. While short-term mortality was not statistically linked with any treatment group, the greatest percentage of mortality (24%) occurred for fish that had barbed hooks removed using the through-the-gill method. These data suggest that when anglers use barbed hooks and encounter a deeply hooked fish, cutting the line poses the least risk to the fish.

Automated summary

Sustainable catch-and-release fisheries assume most fish survive angling events. Best practices are important to mitigate post-release injury, behavioral impairment, and mortality. Deeply hooked fish pose a major risk to survival, and it is generally better to cut the line than remove the hook through the gills. However, anglers have shown interest in removing hooks through the gills, but this method increases the likelihood of sublethal outcomes. Barbed hooks and through-the-gill removal resulted in lower fish condition and survival, as well as higher rates of bleeding, gill damage, esophageal tearing, and reflex impairment.