ML070390563
| ML070390563 | |
| Person / Time | |
|---|---|
| Site: | FitzPatrick  |
| Issue date: | 03/01/2002 |
| From: | Sarah Lopas US Dept of Interior, Geological Survey (USGS) |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| Download: ML070390563 (2) | |
Text
Great Lakes Science Center Preyfish Population Assessment T he USGS Great Lakes Science Center is dedicated to providing scientific information for restoring, enhancing, managing, and protecting the living resources and their habitats in the Great Lakes basin.
The Center is headquartered in Ann regarding these economically important needs. Preyfish population is one of Arbor, Michigan and has biological salmonid predators. the 80 indicators used by SOLEC to stations and research vessels located determine the health of the lakes.
throughout the Great Lakes Basin. State of the Ecosystems Based on the variety of indicators, The Center conducts annual trawl The preyfish assemblage forms Lake Superiors condition has been surveys in all five Great Lakes to important trophic links in the aquatic assessed as mixed and improving.
assess the health of populations of both ecosystem and constitutes the majority Unfortunately, the status of the other predator and prey species. This of the fish production in the Great monitoring leads to a better Lakes. However, preyfish populations understanding of the processes that vary with each lake. Lake Erie, the shape the fish community and to warmest and shallowest lake, is the most productive and has the highest species diversity of preyfish. In contrast, Lake Superior is a deep, cold and relatively unproductive lake, unique in that it is the only lake that can support a naturally reproducing population of lake trout. In 2002, scientists from the Great Lakes Science Center assessed the health of the populations of preyfish for the biennial The exotic alewife, a dominant preyfish species in every Great Lake with the State of the Lakes Ecosystem Conference (SOLEC) to Lake Erie biomass of forage fish species.
exception of Superior. Spiny-rayed fish include young yellow perch, provide information to policy makers white perch and white bass; soft-rayed include on the status of the lakes and future trout perch and emerald and spottail shiners; identify those characteristics critical and clupeid are young gizzard shad and alewife.
to each species.
four lakes has been assessed as mixed Throughout the years, stocking and deteriorating.
programs for lake trout, Pacific salmon and other salmonids have been Lake Erie established to rehabilitate those A species-rich and highly productive populations left devastated by sea lake, Lake Erie has shown declines in lamprey predation and over fishing. recruitment of forage fish in recent These species are sustained by preyfish years most likely due to an increase in populations of alewife, rainbow smelt, R/V Kiyi, the Great Lakes Science Centers invasive zebra mussel colonization.
bloater, sculpin and lake herring. The largest vessel, conducts surveys and research on These mussel populations filter food assessment of the preyfish populations Lake Superior. The Center also has large ships out of the water column and reduce the on lakes Erie, Huron, Michigan, and Ontario.
is vital in management decisions available resources for small fish.
U.S. Department of the Interior Great Lakes Science Center GLSC Fact Sheet 2002-3 U.S. Geological Survey 1451 Green Road Ann Arbor, MI 48105 (734) 994-3331 www.glsc.usgs.gov
Lake Michigan have been declining as alewives Lake Michigan species have been become the most abundant preyfish.
experiencing some declines in recent years, some due to natural cycles in abundance, others because of high predation pressure. Bloaters seem to be experiencing these natural cycles; they have been steadily declining since 1990, but Deepwater sculpin is a common forage fish in Lakes Ontario, Michigan and Huron. Its are expected to rebound in the next numbers are declining due to competition few years. The non-native rainbow with round gobies.
smelt and alewife have declined possibly in response to predation by Lake Superior stocked salmonids. Not significantly impacted by zebra Disturbing declines in yellow perch mussels due to cold water and Diporeia (a small crustacean Lake Hurons preyfish biomass. temperatures, Lake Superior is the Sampling was not completed in year 2000.
many fish use as a primary food) bright spot on this bleak report.
Lake Ontario Dominated by alewives and rainbow smelt, Lake Ontarios food web has been particularly damaged by invasive species. Populations of forage fish have moved to increasingly deeper waters as zebra and quagga mussels colonized most Lake Superior preyfish biomass.
of the lake bottom, and currently the fish species remain in the deeper Lake Superiors condition has been water. Slimy sculpin populations improving over the last few years, Lake Michigan preyfish biomass.
declined sharply coincident with the and declines in prey fish are the collapse of Diporeia (most likely result of a recovery in wild lake have been attributed to increasing caused by zebra mussels) and no trout stocks, not of worsening zebra mussel colonization and the deepwater sculpin were caught at all conditions.
disruptions they cause to the food in 2000-2001. Scientists consider Lake trout were decimated by over-web. Another invasive that could Lake Ontarios condition to be the fishing and sea lamprey predation, potentially impact the preyfish worst of the lakes. and had fallen to historical lows in community is the round goby, a the 1960s. Recovery began in the highly competitive benthic fish from mid-1980s and some species, Eurasia, which is colonizing particularly sculpins, burbot, and increasingly deeper areas of the stickleback have been declining lake. since under heavy predation pressure. Bloater biomass has Lake Huron nearly doubled since the early Similar to Lakes Michigan and Erie, 1980s, and lake herring has Lake Huron has been experiencing recovered to a point where the the negative impacts of the zebra commercial fishery could be mussel invasion, as well as the re-established.
arrival of the round goby. Lake Hurons fish community is dominated by non-native species, such as alewife and smelt and predation pressure by salmonids Lake Ontarios preyfish biomass, dominated by predominantly determines their 2 non-native species, alewife and smelt.
populations. Bloater populations U.S. Department of the Interior Great Lakes Science Center GLSC Fact Sheet 2002-3 U.S. Geological Survey 1451 Green Road Ann Arbor, MI 48105 (734) 994-3331 www.glsc.usgs.gov