The effect of targeted stocking on behaviour and space utilization of a released finfish

Abstract

Targeted stocking involves the release of fish directly into high-quality habitat, however this is often time-consuming, expensive and difficult. Acoustically tagged hatchery-reared juvenile mulloway Argyrosomus japonicus were released in groups directly into deep-hole habitat preferred by wild conspecifics (targeted stocking), or in a non-targeted fashion near easily accessible sites that lacked high-quality habitats in the direct vicinity. Fish were tracked continuously, 24 h d-1, for 5 d following release. Fish released in a targeted fashion showed lower mean activity rates (50% less movement) and occupied higher quality habitats than fish released in a non-targeted fashion. Fish released in a non-targeted fashion also used a greater number of smaller habitat patches. The implications for improvements in behaviour and habitat usage patterns for fish released in a targeted fashion, such as improved growth and survival, are discussed. Identifying and releasing fish directly into the species' high-quality habitat may ultimately improve the success of stocking programs. © 2014 International Council for the Exploration of the Sea. All rights reserved.