Postrelease survival of Little Tunny  Euthynnus alletteratus in a recreational fishery

Abstract Objective The Little Tunny Euthynnus alletteratus is the target of an intensive catch-and-release recreational fishery throughout the U.S. East Coast. However, no estimates of postrelease survival are available to quantify the magnitude of incidental mortality in the fishery or to inform nascent management efforts and recommend best catch-and-release practices to anglers. To fill this data gap, we used acoustic telemetry to assess the fates of Little Tunny that were caught and released by recreational anglers and to calculate conditional and overall rates of postrelease survival. Methods Little Tunny (n = 49) were caught using standard rod-and-reel fishing gear, tackle, and practices aboard recreational charter vessels in Nantucket Sound, Massachusetts; tagged with external acoustic transmitters (n = 20 of which were capable of recording vectorized biaxial acceleration), and monitored by an extensive array of acoustic receivers deployed throughout the region. Survival was inferred based on visual assessment of acceleration values and the extent of horizontal movement between acoustic receivers. Survival rates were estimated using Kaplan–Meier survival curves. Results Thirty-eight of the 49 fish were assigned as survivors, and hook location had the greatest effect on survival, wherein 86.5% of fish with shallow hook placement (i.e., in the jaw), 27.6% of fish with mid or deep hook placement (i.e., deeper than the jaw), and 78.0% of fish with foul hook placement survived, although the foul category was not found to be significant. By adjusting these conditional rates based on the distribution of shallow (77.7%), mid/deep (14.3%), and foul (8.0%) hook locations in the sample, the resultant overall postrelease survival rate was estimated at 77.3%. Conclusions Little Tunny are resilient to the effects of catch and release by recreational fishers, but mid and deep hook locations were found to lower the rate of survival. Anglers should consider modifications to tackle and practices that maximize the incidence of hooking in the jaw and that mitigate injury and stress in the event of internal hooking.