Unintended consequences in restoration : investigating interactions between trout habitat enhancement and anglers in western streams

Abstract

Previous research spanning lotic, lentic, and marine environments suggests that habitat enhancement structures (HES) may attract and concentrate fish from adjacent habitats rather than increase fish populations. In addition to concentrating fish, we hypothesized that anglers may target HES, and therefore, that fish concentrated at HES may be more susceptible to angling. To test our hypotheses, we assessed spatial patterns of: 1) habitat structure; 2) fish holding locations; and 3) fishing pressure (i.e., casting patterns) in southwestern Montana stream reaches with HES. Findings suggest that HES aggregate fish and that anglers more successfully target fish holding near artificial HES than similar densities of fish holding further from artificial structures (e.g., near natural holding structures). We conclude that installation of HES may increase angling opportunities, but could also act as fish population sinks by focusing fishing pressure over likely fish holding areas.