Lake whitefish, currently the number one commercial fish in the Great Lakes and a key indicator of ecosystem health, are once again reproducing in the Detroit River according to scientists with the U.S. Geological Survey (USGS) and the U.S. Fish and Wildlife Service (USFWS).
Scientists from the federal agencies discovered spawning lake whitefish and fertilized whitefish eggs in the Detroit River last fall, the first documented spawning of the fish in the river since 1916. The discovery provides further evidence of progress in the ecological recovery of the Detroit River, home to North America's only International Wildlife Refuge and International Heritage River System.
The Detroit River recently received international acclaim at the White House Conference on Cooperative Conservation for its progress toward ecological recovery and for the public and private partnerships that have worked to revitalize the storied river. The river is now a major catalyst in the economic redevelopment of the Detroit River waterfront and the revival of a glorious "front porch" for the region.
"The return of lake whitefish to the Detroit River is partially the result of 40 years of pollution prevention and control activities in the Detroit/Windsor metropolitan areas", said Dr. Leon Carl, Center Director, USGS Great Lakes Science Center. "Scientists are continuing studies of this unique river ecosystem to learn more about the habitat needs of lake whitefish and other native fish that may potentially lead to the re-establishment of this heritage fishery."
The Detroit River was well known for its whitefish fishery in the 1800s and early 1900s, but habitat loss and degradation, pollution, and other factors contributed to the loss of this important fishery. The river began its recovery in the early 1970s with the U.S. and Canada Great Lakes Water Quality Agreement and passage of the U.S. Clean Water Act in 1972. Other federal, state and local initiatives have since helped to reduce the volume of pollutants entering the river. Compared to 1972 levels, discharges of oil have been reduced by 98 percent and phosphorus discharges reduced by 95 percent. Scientists have also measured a 70 percent decline in mercury contamination in fish and an 83 percent decline in PCB levels in herring gulls from Fighting Island. The Detroit River now has reproducing populations of peregrine falcons, lake sturgeon, and bald eagles, and is gaining a national reputation as a world-class walleye fishery.
"This whitefish recovery is helping transform the river into an internationally recognized wildlife refuge that will provide an exceptional ecotourism experience to residents of Southeast Michigan and Southwest Ontario," said Dr. John Hartig, refuge manager at Detroit River International Wildlife Refuge.
Scientists will continue to assess a number of sites in the Detroit River and in the Huron-Erie Corridor (which also includes the St. Clair River, Lake St. Clair, and western Lake Erie) to determine where whitefish are spawning, what their habitat requirements are, and other information on growth and reproduction. Whitefish eggs and larvae collected in 2005/2006 were brought back to the USGS Great Lakes Science Center in Ann Arbor and are now being raised in the lab. Results from this research will help direct fisheries managers in future efforts to restore native fish populations and habitat in the river.