Comparison of Fish Communities from 32 Inland Lakes in Isle Royale National Park,1929 and 1995-1997

摘要

Fish communities in 32 of Isle Royale National Park's inland lakes were surveyedin 1995-97 to determine if their composition had changed significantly since 1929 when the last complete survey was conducted. Gill nets, seines and minnow traps were used for sampling the lakes, the surface areas of which were 1.2-1,635 ha and maximum depths of which were 1.5-46.3 m. The 1995-97 collections contained 28 of the 30 fish species reported in 1929. No new fish species were collected. Observed changes in the fish communities included no change (14 lakes), additional species (11 lakes), and undetected species (12 lakes). In five lakes, both species gains and losses were observed. Most gains seemed to be because of upstream dispersal from a downstream lake or a Lake Superior cove at the outlet of the watershed. Compared to those of mainland lakes and adjacent Lake Superior, the communities in Isle Royale's inland lakes have changed relatively little since 1929. As a result, continued conservation of these native fish communities will provide further opportunities for understanding issues such as dispersal, isolation, and speciation.