Chinook salmon slim down

"The length is there, but the weight is not," fisher Lance Larson told the Times Herald of Port Huron for a story yesterday.

Larson, of Lexington, is not alone in his observation.

State fisheries biologists said they're concerned that the 3-and 4-year-old chinook salmon fish are working too hard to find something to eat.

In the long run, that could open the chinook population in Lake Huron to a kidney disease that could destroy the multi-million dollar fishery.

A 1996 Travel Michigan study shows sport fishing accounts for about $1.5 billion spent in the state.

Jim Johnson, a fisheries biologist at the Department of Natural Resources in Alpena, said researchers in the fall of 1997 noticed smaller chinook at Rogers City and in the Au Sable River.

The 4-year-old fish were on average about four pounds lighter than the year before. The 3-year-olds were about two pounds lighter.

Jim Baker, a Bay City DNR district fisheries biologist, said the trend continued this summer.

"Our fishermen are telling us this year that they're having a hard time catching a fish more than 12 to 16 pounds," he said. "Twenty pounds is extremely rare."

Bill Van Luven of Marysville, who runs a charter out of Grindstone City, said fish have been smaller, but anglers caught lots of them.

"We're getting 12- and 14-pound fish instead of 20- to 25-pounders," he said.

Fisheries biologists believe the drop in weight is related to a scarcity of alewives.

Chinook feed almost exclusively on the small fresh and saltwater fish.

Johnson said a Lake Huron netting survey this summer found few large adult alewives.

"But they're reproducing well," he said. "That's good for little chinooks. They have plenty of little alewives to eat.

"But big chinooks, they're working harder and enjoying it less."

Skinnier chinook are less resistant to bacterial kidney disease.

The illness in 1986 ravaged chinook in Lake Michigan, collapsing the fishery there.

In Lake Huron, salmon largely avoided the disease and business remained steady.

The DNR is proposing to cut Pacific salmon stocking in Lake Huron by 700,000 to 800,000 fish in May 1999 both in Michigan and Canadian waters.

Last year, 4 million chinook and coho were stocked in the lake.

Fisheries biologists hope that would enable the forage fish populations to remain steady.

Johnson said the state initially introduced Pacific salmon into the Great Lakes to control alewife populations.

Alewives are invaders from the Atlantic Ocean that entered the lakes through the St. Lawrence Seaway.

They dominated the food chain in the lakes in the 1960s after another invader - the sea lamprey - decimated native predators such as lake trout.

The decline in salmon weights could indicate that Lake Huron has reached its capacity to sustain chinook at large weights in large numbers, Johnson said.

Cutting the alewife population in Lake Huron has been one of the DNR's goals since stocking began, Johnson said.

"One of our objectives is to rehabilitate our native species," he said. "This is not a bad thing. We've controlled alewives. Now we're tweaking the system."

10-12-98