Spring 2003 Issue

Anglers often think they are doing the right thing when they introduce a new fish species into a lake or river. They think they are improving bass or striper fishing by providing more forage, but more often than not, native fish suffer as a result.

Unauthorized stocking of non-native fish has biologists concerned. "All it takes is two," said Gerry Buynak, state fisheries research biologist. "And it can have a devastating effect on our sport fisheries."

Alewives are one cause for concern. They first appeared in Dale Hollow in 1976 and Lake Cumberland in 1991. They’re now showing up in more lakes around Kentucky. "We’re having a rash of alewife introductions," Buynak said. "They’re getting distributed everywhere. You never know where they’re going to show up next."

It is illegal for the public to stock native or non-native species, such as alewives. It is legal to collect alewives in lakes with established populations, and use them for bait on the same lake.

Alewives are a shad-type fish native to the East Coast of the United States. Like stripers, they live their lives in the sea, then come into freshwater rivers to spawn. Like stripers, they also can live their entire lives in fresh water.

Alewives are the preferred prey of Lake Cumberland’s stripers. Walleye also find these baitfish tasty — perhaps one of the reasons alewives are showing up in more Kentucky lakes. Kentucky officials once considered stocking alewives, but rejected the idea because there were too many unknowns. Current research indicates that was a wise decision.

All newly-hatched fish depend on tiny plants and animals, or zooplankton, to survive. Some scientists believe competition from alewives for zooplankton helped cause a decline of native fish species in the Great Lakes. In Kentucky, biologists noticed stunted growth of walleye fry in a lake where alewives had a foothold. Buynak said biologists aren’t sure if there is a direct connection.

Unlike shad, which are unwelcome visitors in Kentucky’s smaller state-owned lakes, adult alewives also eat eggs and larva of other fish, including largemouth bass, white bass, walleye, trout and panfish. "Egg and larval predation by alewives is considered a major mechanism by which alewives affect native species, potentially more important than competition for food," according to the Vermont Agency of Natural Resources.

The same agency notes "alewives are the cause of major reproductive failures in landlocked Atlantic salmon and lake trout populations" due to a vitamin deficiency created by an alewife-intensive diet.

Benjy Kinman, fisheries director for the Kentucky Department of Fish and Wildlife Resources, said Kentucky hasn’t done any studies on the impact of alewives on the state’s lakes. "That would be difficult to measure. It would also take my whole budget," he said. "There’s not a lot we can do now — they’re already here."

If you’re tempted to "improve" fishing in your favorite lake by tossing in a new species of baitfish or game fish, don’t do it. The Pandora’s Box you open often can’t be closed. 

Copyright 2003 Kentucky Afield Magazine.  All rights reserved.