Ichthyofauna of the Great Lakes Basin

The fish community of the Laurentian Great Lakes is typified by change.  The retreat of glaciers and geologically ephemeral connections to source populations in the Mississippi, Atlantic, and Bering Sea basins created a relatively unique fish assemblage where cold, cool, and warm-water species co-exist.  In recent history, introductions of non-native species, habitat loss, eutrophication, and harvest have been important agents of fish community change in the Great Lakes.  I will discuss some of the factors that influence the current ichthyofauna of the Great Lakes, particularly focusing on non-native species.  We define the Great Lakes Basin as all connected waters south of Ogoki Lake in the north to the St. Lawrence Seaway in the south and east.  We exclude the Illinois River, although arguments can be made towards its inclusion given the history of species introductions through the Chicago Sanitary and Shipping Canal.  To date, the vast majority (78%) of fish species in the Great Lakes are native, with Lake Ontario containing the highest percentage of native species (88%), and Lake Superior containing the lowest (77%).  However, non-native species make up a significant and increasing portion of the fish community.  In total, 34 non-native species are established in the Great Lakes basin, including fish that were purposefully stocked.  Although relatively few in number, non-native species play a particularly important role in the ecology and management of the Great Lakes.   I will discuss donor regions, introduction routes, and detail some impacts of non-native species.  In terms of native species, I will present information on range expansions and taxonomic uncertainty that muddle ideas of the ‘native’ vs ‘non-native’ classification schemes.  Lastly, I will discuss research priorities related to identifying future agents of species change in the Great Lakes, including climate change, further non-native species introductions, and how multiple stressors could interact to influence fish communities.