Pollution not likely cause of fish die-off, officials say

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09/20/07 By Rosemary Parker ** you do not have permission to see this link ** 388-2734

Fisheries experts will monitor reports of dead fish in the Kalamazoo River in Allegan County, but so far there's no need for much worry, a fisheries manager said.

Scientists say they don't think there's been any discharge of toxic chemicals because the die-off seems to be confined to a single species — golden redhorse suckers — that makes up about 20 percent of the biomass in the river, said Jay Wesley, fisheries unit manager for the Michigan Department of Natural Resources field office in Plainwell. The dead fish have been found between Otsego and the Trowbridge Dam.

“We got a report late yesterday and we went to Trowbridge Dam and saw 10 to 20 dead fish; today we only saw five or six,'' Wesley said Wednesday. “Earlier in the day some kayakers thought they saw thousands.''

The fish, shaped like a small carp, are bottom feeders that grow to 12 to 18 inches in length.

Wesley said the fish have some sort of bacterial or viral infection that became fatal when they were stressed by the recent fluctuation is temperature.

These fish typically run in schools and can pass diseases back and forth, he said.

“It is unusual to see this number die, especially of that species,'' Wesley said. Unless the die-offs continue, however, the DNR will not investigate further, he said.

Sick or dying fish, not dead ones, are required for analysis, Wesley said, and that's an expensive proposition not warranted at this point. “Right now,'' he said, “we are just making sure there's no ongoing kill.''

Fish facts

Sometimes a specific stress, such as the recent weather change, pushes already ailing fish to the point of death.

Although sampling has not yet been deemed necessary for golden redhorse suckers that have been dying in the Kalamazoo River, if that step is taken it may take six weeks to get results from tests.

There are thousands of pounds of fish per mile in the Kalamazoo River.

Typically, diseases that infect fish do not affect humans, though as a precaution anyone who eats fish should cook them first. Also, there are fish-consumption advisories for many species on the Kalamazoo River because of chemical contamination.

If you see sick or dying fish, call the DNR office in Plainwell at 685-6851.