Great Lakes whitefish in decline
Whitefish numbers are down in some parts of the Great Lakes, and it is believed zebra and quagga mussels are to blame.
Fish populations fluctuate with water quality, food web changes, and introduction of new species, MNR spokesperson Mike Fenn said. “Factors vary, but the arrival of zebra and quagga mussels during the 1980s played a big part, as they contributed to increased water clarity in some lakes, affecting growth of aquatic plants, the food web dynamic, and in turn, the fish community,” he said. “Zebra mussels can change the movement of nutrients in Great Lakes fish communities and potentially reduce fish production. Water clarity has also been observed to increase because of the filtering activity of zebra mussels. This can lead to negative shifts in the fish community.”
Whitefish populations across the Great Lakes have been affected differently. In Lake Huron, over the last 20 years, whitefish have declined in varying degrees.
Numbers have also slid in Lake Ontario, and remain at a low, but stable, level. Whitefish are still commercially harvested in eastern Lake Ontario and the Bay of Quinte.
In Lake Superior, whitefish are stable except in Nipigon Bay and eastern Lake Superior. Invasive mussels were recently found in Nipigon, but their impact is not known.
Lake Erie’s has also seen a whitefish decline in recent years. Commercial harvest of the species there ceased in 2013.