Monitoring fish behaviour with a remote, combined acoustic/radio biotelemetry system

Biotelemetry is a powerful instrument for monitoring aquatic species in the ir natural environment. Using telemetry, animals can be monitored from a pa ssive perspective, without the biases associated with conventional handling and sampling techniques. To monitor aquatic species in remote environments , with vast stretches of water, and in situations requiring both acoustic a nd radio transmissions (e.g. for diadromous fish), advances in telemetry ar e necessary. In this paper, a field-proven telemetry system based on a radi o receiver and incorporating combined acoustic and radio smart transmitters , wireless hydrophones and two-way satellite communications is described. T he system was first deployed in Bay d'Espoir, Newfoundland, Canada, in 1998 . The purpose of this deployment was to determine whether aquaculture tripl oid steelhead trout (Oncorhynchus mykiss Walbaum) (1.5-2.0 kg), experimenta lly released in the vicinity of a commercial aquaculture site, remained at the site (site fidelity) or dispersed. Two sets of fish releases, summer an d winter, were performed to determine seasonal effects on the movement of a quaculture triploid steelhead trout in the wild. The results suggested stro ng site fidelity among steelhead trout when released during the growing sea son (summer). However, less fidelity was displayed for the winter released steelhead.