Sunday, June 13, 2010

Gulf of Maine Alewife Research

While the alewife run in Maine is in full swing, the Gulf of Maine Research Institute (GMRI) and the University of Southern Maine (USM) are collecting alewife samples as part of an effort to unlock some of the mysteries surrounding this important forage species. Study locations include more than 20 river systems and lakes along the Gulf of Maine coast.

Alewives are currently making their annual spawning runs from the ocean to freshwater lakes. Despite their historical commercial and cultural importance to Maine communities, there is still much to be learned about alewife ecology. Alewife populations along the Atlantic coast have exhibited dramatic declines over the past 20 years despite efforts to remove dams and restore waterways. These efforts have led to recovery in some systems but not in others.

It is unclear where alewives migrate to after leaving freshwater for the ocean or whether the fish born in a particular lake continue to school together or mix with other alewives in the ocean. If alewives from specific freshwater systems can be distinguished from each other, as this research project is investigating, researchers and managers may be able to better monitor population dynamics of alewife from specific runs, evaluate the impact of the unintended capture on specific alewife populations, and unlock the mystery of where alewives go once they leave Maine rivers.

Many communities lease permits to alewife harvesters, and most of the catch is sold as lobster bait. The sheer numbers of alewives that run up rivers provide protection for returning adult Atlantic salmon running up these same rivers and for Atlantic smolts that are moving downstream to the ocean at this time of year. Alewives are also a food source for osprey, herons, otters, cod, haddock, and other animals.

Maine's alewife population is relatively healthy compared to other states, but scientists do not know why. Massachusetts, Connecticut, Rhode Island, North Carolina and Virginia have closed their alewife fisheries, and Maine may be forced to do the same unless the fisheries are proven to be sustainable.

USM and GMRI researchers will provide critical information to help determine why some alewife populations are not recovering, and inform management decisions on the conservation and sustainable use of this valuable forage species.

source: Gulf of Maine Research Institute

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