Fish distribution and benthic invertebrate biomass relative to depth in an Ontario lake

Abstract

A survey of fish distribution relative to depth in Lake Opinicon, Ontario, using the strip count method showed 80–90% of the biomass to be concentrated along the lake margins at a depth of up to 2.5 m. This figure applied throughout the summer, and to both day and night. Invertebrate diversity and biomass was also biassed towards the margins but slightly less so (mean summer figure 68% of biomass at depth of 2.5 m or less) for the segment of the lake studied. The central parts of the lake have good populations of 1–2 cm Chironomus spp. not predated by fish.