Species occurrence data were obtained from the Atlas of Spawning and
Nursery Areas of Great Lakes Fishes (Goodyear et al. 1982). The
atlas contains information on all of the commercially and recreationally
important species that use the tributaries, littoral and open-water
areas of the Great Lakes as spawning and nursery habitats.
Close to 9500 geo-referenced data records (occurrences of fish species)
were imported into ArcView GIS.
The 139 fish taxa reported in the Atlas had to be grouped into
fewer broad categories to produce meaningful distribution maps. We
chose three functional classification schemes. Jude and Pappas
(1992) used Correspondence Analysis to partition fish species associated
with the open water of each of the five Great Lakes and nine coastal
wetlands. Three species complexes were suggested: a Great
Lakes taxocene; a transitional taxocene, which utilized open water,
near-shore, and wetlands; and a wetland taxocene. We chose this as
one of the classification schemes because we are particularly interested
in identifying the distribution pattern of fish with coastal wetlands;
for clarity sake, we have renamed these taxocenes coastal, intermediate
and open-water, respectively. For comparison, we also used
Coker et al.s (2001) classification based on temperature preferenda (5
classes) and Balons (1975) reproductive guild classification (32 guilds).