Catch and Release in Marine Recreational Fisheries

Survival of Juvenile Northern Bluefin Tuna Following Catch and Release, using Ultrasonic Telemetry

R. Brill, M. Lutcavage, G. Metzger, P. Bushnell, M. Arendt, and J. Lucy

doi: https://doi.org/10.47886/9781888569308.ch23

Current population assessments for northern bluefin tuna Thunnus thynnus are based primarily on catch-per-unit effort data from fisheries targeting both adults and juveniles, but remain highly controversial. As a result, aerial surveys have been used for population assessments of adults (Lutcavage et al. 1997), and similar fishery-independent measures of juvenile abundance are considered a priority. Juvenile northern bluefin tuna (formally defined as age-classes 1–5 years, body mass 6–60 kg) appear in the surface waters off the east coast of the United States (from North Carolina to Rhode Island) in June and July (Mather et al. 1995) and present an opportunity for population assessments using aerial surveys. Design of the surveys and interpretation of the data can be significantly improved, however, by an a priori understanding the distribution and behavior of these highly mobile fish in relation to oceanographic conditions (Newlands and Lutcavage 2001). We, therefore, undertook a study of the horizontal and vertical movements of juvenile bluefin tuna using ultrasonic depth-sensitive transmitters. Because fish behaviors were monitored continuously for up to 48 hours, we were also able to assess survival following catch and release.