A float-release package for recovering data-loggers from wild sharks

•A data-logger release and recovery package was developed for free-living sharks.•The package had a recovery success of 95.7% across 47 deployments.•The package had successful deployments on blacktip, bull, nurse, and white sharks.•Deployment durations ranged from 1–111 h.•The maximum shark displacement distance was 35 km.

The rapidly expanding use of high-resolution data-loggers to study marine vertebrates presents a wealth of new opportunities for understanding the behavior, physiology, and ecology of these animals in situ. It also presents a number of new logistical challenges, one of the biggest of which is the need to physically recover the tag in order to acquire data, thus, a novel data-logger release and recovery package was designed and tested. This package consisted of a microsphere-resin float, very high frequency (VHF) transmitter, and galvanic timed release (GTR) device which allowed acceleration data logger (ADL) tags to remain on free-living sharks for several days before detaching from the fin. Upon release, tags floated to the surface and were located using a VHF receiver and yagi antenna. This method has been used successfully on blacktip, bull, nurse, and white sharks to produce an overall recovery rate of 95.7% on 47 deployments over periods of 1–111 h and shark displacement distances up to 35 km. This represents a cost-effective method for recovering data-loggers from sharks and large teleosts.