Abstract

Recent studies conducted in 2018-2019 estimated that the lobster fishery on the Saba Bank catches a significant number (1400-400) of nurse sharks (Ginglymostoma cirratum) as bycatch. Through a collaboration with fishermen, the Saba Bank Management Unit, Mote Marine Laboratory, and the Dutch Elasmobranch Association, a three-year monitoring project was conducted to estimate the recapture rate of nurse sharks in the lobster fishery. The study aimed to determine the recapture rate of nurse sharks, the time taken for them to return to their original capture location and provide an updated annual estimate of nurse sharks caught in the lobster fishery. By addressing these objectives, the study sought to understand why nurse sharks enter lobster traps and update the estimation of their population size. Results showed that tagged nurse sharks were recaptured on average after 76 days, with no significant difference between males and females in terms of freedom days. Females exhibited site fidelity over multiple years, while males appeared to visit more seasonally. Among the 118 tagged sharks, a 30% recapture rate was observed, suggesting that the actual number of individual nurse sharks caught annually may be lower than previously estimated. Experiments conducted in controlled environments and in the field revealed that nurse sharks did not attack the lobsters in the traps, despite the presence of bait. Preliminary field footage indicated that nurse sharks entered the traps before the lobsters, suggesting that their primary motivation for entering the traps may not be the regular pray