The Effects of Half-Log Covers on Angler Harvest and Standing Crop of Brown Trout in McMichaels Creek, Pennsylvania

Abstract

Approximately 40 m 2 of supplemental shelter provided by 68 half-log cover devices were added to 700 m (0.52 hectare) of McMichaels Creek, a relatively infertile stream in eastern Pennsylvania. A control area of similar size was left undeveloped. Angling data and yearly electrofishing inventories were used to measure changes in the standing crops of brown trout (Salmo trutta) ≳ 200 mm (catchable-size) and 100-199 mm long (subcatchable). Anglers creeled 10% more trout in treated sections after cover installation, whereas the brown trout harvest declined by 11% in the untreated sections. The number and weight of larger trout collected by electrofishing in half-log sections rose by 12% and 14%, respectively. However, these increases that amounted to 18 more trout/hectare/year were not statistically significant and were evident before the devices were installed. Numbers and biomass of brown trout ≳ 200 mm in control sections declined in postdevelopment years. Standing crops of smaller trout increased significantly in both cover and control sections, with the greatest changes occurring in control areas. Total combined weight for ≳ 100 mm was significantly higher (20%) in the treated sections, while trout biomass fell an insignificant amount (11%) in the undeveloped sections. The poor response of catchable-size brown trout to cover enhancement in McMichaels Creek was attributed to the presence of abundant natural cover. Environmental factors other than shelter apparently determined the density of subcatchable trout.