Movement and mitigation of domestic triploid steelhead trout (Oncorhynchus mykiss) escaped from aquaculture grow-out cages

In this study I monitored escapee movement, by tracking transmitter-implanted domestic female triploid steelhead trout in the wild using sophisticated biotelemetry fixed data-logging and manual tracking techniques, in Bay d'Espoir, Newfoundland, Canada. Of the 68 triploid steelhead released on-site, in July 1998, 51 (75%) remained within a 500 m radius of the summer grow-out site 32 days after release. Similar to on-site released triploid steelhead, 17 of 66 (26%) triploid steelhead released approximately 1000 m outside of the summer grow-out site returned to the site within 4 hours of release. Subsequent tracking found that an additional 26 triploid steelhead had returned to the summer grow-out two days after release, bringing the total number of off-site released triploid steelhead return to 65%. Triploid steelhead trout released during the winter displayed lower fidelity than those released in summer.; Dispersing triploid steelhead during summer were detected in the vicinity of other salmonid aquaculture sites throughout the bay. Summer and winter released triploid steelhead both displayed a directed movement upstream towards the hydroelectric spillway—also the location of the local salmonid hatchery. (Abstract shortened by UMI.)...