Ontogenetic Changes in Dispersal and Habitat Use in Hatchery-Reared Lingcod

Abstract

Preliminary experiments that optimize release methods pave the way to larger-scale releases and proper evaluation methods. One evaluation method is before-after-control-impact, which requires that more animals remain at release areas (“site fidelity” to impact areas) than disperse to control areas. This study tested whether there are release methods that maximize fidelity to the release area and minimize dispersal to nearby areas, which might enable a before-after-control-impact experiment. Lingcod that were 17-months old at release showed greater fidelity to release areas (23% remaining one year after release) than lingcod that were 9- and 11-months old at release. None of the 17- and 21-month-old release groups were detected on more distant structured habitats 44 weeks after release, but 8% and 13% of lingcod from the 9- and 11-month-old release groups were detected at distant structured habitat. Thus, releasing 17-month-old lingcod maximized fidelity to the release area and minimized dispersal to other areas. Differences in fidelity and dispersal rates among release-age groups may reflect ontogenetic changes in dispersal and habitat use patterns that have also been reported for wild lingcod. These behavioral similarities with wild lingcod also suggest that hatchery lingcod have potential to interact and integrate with wild lingcod in nature.