A Simple Model for Predicting Survival of Angler-Caught and Released

Abstract.—We conducted a controlled experiment in the laboratory to assess the influence of anatomical hooking location and water temperature on survival of angler-caught and released largemouth bass Micropterus salmoides. Survival was 98 % (58 of 59 fish) among fish that were hand-hooked within the oral cavity (including the gills), whereas survival was 66 % (33 of 50 fish) among fish that were hand-hooked in the esophagus. Survival of hooked fish was not significantly influenced by water temperature (7–278C) or the hooking location3water temperature interaction. We combined our results with prior research to develop a predictive model of largemouth bass survival, which was 98.3 % (SD 1.87%) for fish hooked in the oral cavity and 55.0 % (SD 9.70%) for fish hooked in the esophagus. The model is valid for water temperatures ranging from 78C to 278C and allows one to estimate, with known precision, the survival of angler-caught and released largemouth bass without the need for controlled studies or for holding fish in pens or cages to assess delayed mortality. Recreational anglers commonly capture and release fish (USFWS and USCB 2002; Roy Morgan Research 2003), either as part of a catch-and-release ethic or because of regulatory requirements. In many fisheries, a substantial portion of the fish population may be captured and released (Schill et al. 1986; Nuhfer and Alexander 1992; Davis 2002). Consequently, survival of released fish can have a major impact on fishery quality. Because of the prevalence and fishery importance of catch-and-release fishing, a substantial body of literature has emerged that relates survival to bait type (including live and artificial baits), bait size, number and size of hooks, presence of barbs, anatomical hooking location within the mouth, depth of capture, angler handling and release techniques, and environmental conditions (Taylor and White 1992