Fisheries leaders cheer reports on Lake Michigan Chinook salmon
Written by Grand Rapids Press   
Monday, 18 January 2010 17:48
State fisheries officials analyzing 2009 Lake Michigan salmon reports are encouraged by what seems to be an improved balance between fish and prey.

Preliminary data shows there likely are fewer, but larger, Chinook in the lake than in previous years, providing further evidence that stocking cuts in 2006 are having the desired effect.

“According to the forage fish surveys we do, it looks like we have seen an associated increase in the alewife biomass,” said Randy Claramunt, Michigan Department of Natural Resources research biologist and chairman of the multi-agency Salmonid Working Group that monitors the lake’s salmon.

That is because “salmon abundance is going down,” said Claramunt, who shared his findings with dozens of charter fishermen and others at a recent Michigan Sea Grant workshop in Ludington.

Chinook salmon, Lake Michigan’s most voracious predators, consume almost entirely alewives, Claramunt said.

In 2006, state and federal resource managers on all sides of Lake Michigan cut chinook stocking from about 4.3 million to 3.2 million in an effort to balance them with a steady decline in forage fish levels, particularly alewife populations.

Budgeting issues and hatchery deaths in Wisconsin also cut Coho stocking numbers by 25 percent to 50 percent in recent years, Michigan DNR officials said.

Mark Tonello, DNR fishery management biologist, said the 2009 data shows they “were on the right track with the stocking cuts” in 2006. He said the DNR is not looking at further cuts for chinook in the near future.

State officials, however, plan to roughly double the number of Coho salmon stocked in the lake next year. Last year, fisheries managers stocked about 580,000 yearling Cohos in the Platte River, a relatively low figure compared to previous years, Tonello said.

“It’s been (because of) budget issues and some health issues at the hatchery as well,” Tonello said.

The state hopes to plant as many as 1.6 million Coho in Lake Michigan this year, he said.

“What we want is to maintain a good balance out there,” Tonello said. “What we don’t want is a fishery that is phenomenal one year and horrible the next year.

But resource managers agree that predation is among many factors affecting the lake’s sportfish and only so much can be controlled.

Evidence shows that invasive species such as zebra and quagga mussels are changing the lakes from the bottom up. Scientists say much of Lake Michigan’s biomass has moved from the water column to the mussels on the lake bottom in recent years, leaving less food for forage fish.

Alewives and bloater chubs, for example, provide around a quarter less energy than they did in the past, according to Steve Pothoven, fishery biologist with the National Oceanic and Atmospheric Association who also attended the Ludington workshop.

Pothoven, scientists with the U.S. Geological Survey, DNR and other agencies expect to launch additional forage fish surveys and studies on the lower food web this year.
 
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