Fish utilization of Great Lakes coastal wetlands

Abstract

Correspondence analysis was used to partition fish species associated with the open water of each of the five Great Lakes and nine coastal wetlands for which data were available. Included in the analysis were 113 species in 25 families. Three species complexes were suggested: a Great Lakes taxocene (31 species); a transitional community which utilized open water, nearshore, and wetlands (35 species); and a wetlands taxocene, comprised of 47 species found to be closely associated with coastal wetlands. The wetland species split into two main groups: permanent residents (e.g., brown bullhead Ictalurus nebulosus, mudminnow Umbra lima, longnose gar Lepisosteus osseus) and migratory species. Migratory species included three subgroups: (1) those that spawned in the wetlands and then left (e.g., northern pike Esox lucius, common carp Cyprinus carpio, white sucker Catostomus commersoni, walleye Stizostedion vitreum), (2) those that used the wetlands as a nursery area (e.g., northern pike, gizzard shad Dorosoma cepedianum, spottail shiner Notropis hudsonius), and (3) those that migrated into the wetland from other wetlands or a Great Lake for shelter, spawning sites, or food; as part of the sustaining process of dispersal of young; or as part of wandering behavior (e.g., burbot Lota lota, rainbow smelt Osmerus mordax, rainbow trout Oncorhynchus mykiss). It was found that most remaining coastal wetlands are degraded or altered to some degree, and are dominated by a characteristic silt- and turbidity-tolerant fish fauna (e.g., common carp, gizzard shad, goldfish Carassius auratus, and brown bullhead). Nevertheless, even degraded wetlands still functioned as important fish habitat by exporting large quantities offish, first to avian, piscine, and mammalian food chains through predation, and second to the Great Lakes as young-of-the-year sport and forage fish. The research implies that a wetland must maintain a connection with a Great Lake to promote and enhance efficient fish utilization of the high productivity of marshes; that additional resilience is provided to species which spawn in wetlands since they can produce two cohorts (one in wetlands and one in the Great Lakes), and that fluctuating water levels are important in sustaining habitat diversity and productivity.