Parasites of Fish from the Great Lakes - Great Lakes Fishery ...

in composition and numbers between locations and appear to be stochastic in nature. This
variability in helminth (parasite) species-richness and low Jaccard coefficients for parasitecommunity
similarity for these same fish species provides more evidence that the parasite faunas
are different among the Great Lakes.
Comparisons of Jaccard coefficients were made for each fish species between lakes and its family
between lakes to determine if differences existed in them in the lake pairs examined. The highest
Jaccard coefficients for the parasite communities for each specific fish species and for the fish
families each fish species is in among the lakes (first and second coefficients), and lowest
coefficients for each specific fish species and for the fish families each species is in (third and
fourth coefficients) (in parentheses) were: Ambloplites rupestris (0.4285, Lakes Huron and
Ontario; 0.4347, Lakes Huron and Erie; and 0.0000, Lakes Michigan and Superior; 0.0689, Lakes
Michigan and Superior); Notropis hudsonius (0.4138, Lakes Superior and Erie; 0.2941, Lakes
Superior and Huron; and 0.1200, Lakes Michigan and Superior; 0.0588, Lakes Michigan and
Erie); Catostomus commersonii (0.6176, Lakes Erie and Ontario; 0.4250, Lakes Superior and
Ontario; and 0.1795, Lakes Michigan and Erie; 0.1311, Lakes Michigan and Erie); Perca
flavescens (0.4821, Lakes Huron and Ontario; 0.5000, Lakes Huron and Ontario; and 0.1795,
Lakes Michigan and Superior; 0.2714, Lakes Michigan and Erie); Coregonus clupeaformis
(0.5000, Lakes Superior and Ontario; 0.4776, Lakes Superior and Huron; and 0.1379, Lakes
Huron and Erie; 0.1250, Lakes Michigan and Erie); Salvelinus namaycush (0.2173, Lakes
Superior and Huron; 0.4761, Lakes Superior and Huron; and 0.0000, Lakes Erie and Ontario;
0.1250, Lakes Michigan and Erie); Osmerus mordax (0.3750, Lakes Michigan and Ontario;
0.3750, Lakes Michigan and Ontario; and 0.1764, Lakes Superior and Erie; 0.1764, Lakes
Superior and Erie). These coefficients indicate that: 1) the highest coefficients for a fish species
and its family may not involve the same two lakes, demonstrating different coefficients may be
obtained when one fish species or fish family is being compared; 2) there is variation between
lakes in that a fish species may share very few species, or it may share a number of parasite
species between lakes; and 3) variation in these coefficients indicates that some parasite species
are host-specific or not host-specific to a certain fish species or fish family.
Each fish species occupies similar habitats in the different Great Lakes, and are therefore believed
to be exposed to similar parasites and their intermediate and paratenic hosts. Also, fish in the
Cyprinidae, Catostomidae, Centrarchidae, Percidae, and Salmonidae in the Great Lakes are
similar to one another when the percentages of major parasite taxonomic groups are compared
among lakes, but the specific parasite species making up each major parasite taxonomic group
infecting fish are not that similar among the lakes. This finding indicates the factors involved in
the occurrence of parasite species in the same fish species are different from Great Lake to Great
Lake. Therefore, the Jaccard coefficients of parasite-community similarity are low among the
lakes. Many protozoan and most monogenean species with their fish-host specificity are not
shared by fish species or fish families, so these parasite groups play a major role in these low
Jaccard coefficients.
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