Lake Erie Committee
For Immediate Release
February 17, 1998

Marc Gaden
Great Lakes Fishery Commission
734-662-3209 x 14

John Cooper
Ontario Ministry of Natural Resources

Phosphorus Targets Achieved in Lake Erie

Fisheries Agencies Recommend Holding-The-Line On Phosphorus Levels

Niagara Falls, ON - Representatives from the five fisheries agencies on Lake Erie don't want changes to phosphorus target levels in Lake Erie until a more thorough scientific review of the situation can be undertaken. Rob MacGregor, Chairman of the Lake Erie Committee of the Great Lakes Fishery Commission, presented the 'hold-the-line on phosphorus' position on behalf of the five fisheries agencies on Lake Erie at a recent session on phosphorus, fisheries and the Lake Erie food web held in Niagara Falls, Ontario. Fisheries managers noted that the significant reductions in phosphorus have benefited Lake Erie but warned that further reductions could have a serious negative impact on the fish stocks in the lake.

They also stated that it would be irresponsible to advocate a position of adding phosphorus to the lake to increase fish production until there is clear scientific evidence that this would be an appropriate strategy. The Committee strongly encouraged all relevant agencies to commit resources and to work together to undertake a scientific review of phosphorus management on Lake Erie.

Phosphorus is the principle nutrient controlling primary productivity in freshwater ecosystems. Primary productivity has a direct and major influence on fish production. Too much phosphorus can lead to excessive amounts of algae while too little phosphorus can reduce the capability of a lake to support large amounts of fish.

By the late 1960s, Lake Erie was suffering from too much phosphorus and was labeled with headlines such as "Lake Erie is Dead". In 1972, Canada and the United States agreed to work together under the terms of the Great Lakes Water Quality Agreement to reduce phosphorus loadings in Lake Erie. Phosphorus loadings are now under control, with phosphorus concentrations at or below the target levels of 15 ug/l in the western basin and 10 ug/l in the central and eastern basins.

The recent invasion of zebra and quagga mussels into Lake Erie have also caused a pronounced change in the lake's food web. The mussels filter phytoplankton and zooplankton from the water and are reducing the food supply for planktivorous fish and juvenile fish. Quagga mussels are linked to a decline in a key food organism for fish in the deep waters of the eastern basin, while in nearshore areas of the lake quagga and zebra mussels have been associated with greater productivity of bottom-living organisms which are potential food for some species of fish.

Recent declines in the abundance of some of Lake Erie's most important fish species, such as yellow perch, rainbow smelt and walleye, are thought to be strongly related to the combined efforts of reduced phosphorus loadings and the invasion of zebra and quagga mussels. A considerable amount of science needs to be devoted to understanding and unraveling the relative and cumulative effects of mussels and phosphorus concentrations on the fish production of Lake Erie.

Some people, for example, are seeking a quick fix to the declining abundance of the important fish species. They suggest that increasing the loading of phosphorus-largely controlled by sewage treatment plants-to Lake Erie will increase the primary productivity of the Lake Erie ecosystem and hence fish production.

There are concerns, however, that phosphorus additions may lead to near shore increases in algae which caused the nuisance problems on beaches in the 1960s and '70s. There are also concerns that phosphorus additions may cause increased algae blooms and lead to taste and odor problems in water supplies. It is not clear from the current level of scientific understanding whether increases in phosphorus loadings may simply lead to increased abundance of zebra and quagga mussels while having little effect on improving fish production. Another concern is that the chemical process that removes phosphorus from waste water also removes other harmful elements before entering the lake.

Further reductions in phosphorus levels may result in a cleaner, clearer lake but could result in a change in the mix of fish species in the lake and a reduction in the abundance of fish. Lake Erie currently supports a thriving sport and commercial fishery that provides important economic and social benefits to both Canada and the United States.

Much of this issue of phosphorus and water quality is being considered within the Lakewide Management Plan, or LaMP, a requirement under the water quality agreement. Over 30 agencies from seven jurisdictions around the lake are participating in the plan. Citizens from Canada and the United States are playing a prominent role through their participation in the Public Forum of the LaMP.

The Lake Erie Committee is composed of a representative from each of the five fisheries agencies on Lake Erie - Michigan Department of Natural Resources, New York Department of Environmental Conservation, Ohio Department of Natural Resources, Ontario Ministry of Natural Resources and Pennsylvania Boat and Fish Commission.

The Great Lakes Fishery Commission is a U.S./Canadian organization established by the 1955 Convention on Great Lakes Fisheries to study and advise on issues and measures related to the maximum sustained productivity of fish stocks of common concern and to carry out a sea lamprey control program.

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