Temperatures, just as News 4 reported in March


What is causing hundreds of fish to die?

Buffalo, N.Y. - Canalside is just weeks away from being packed with people attending summer events. But visitors could be met with hundreds of dead fish in the water.

Hundreds of dead fish started washing up from Lake Erie, the Niagara River and their tributaries in March, and News 4 reported after concerned viewers called about the dead fish. And though it's been months, you can still find dozens of them floating in the Commercial Slip.

Donald Zelazny, the DEC's Great Lakes Program Coordinator, said, "This is actually one of the larger die-offs of these fish that we've seen in quite a while."

So it's no surprise that people who see them are worried about disease and pollution. But the DEC now has biological evidence of what it has said all along: these fish, a member of the herring family called "gizzard shad," died of natural causes.

"They're very susceptible to cold temperatures and temperature fluctuations. So we generally see a die-off of this particular type of fish every year," Zelazny explained.

The DEC sent biological samples to labs at Cornell University. All the results came back negative.

The fish are an unsightly nuisance for boaters and other people coming down to the water. But fortunately, nature has a way of cleaning up after itself, which is another good indication that the fish are not diseased.

"In the late 1990s, early 2000s, we were seeing a lot of dead fish, a lot of dead birds along the Lake Erie shoreline; and even a lot of what we call "hellbenders," they're like large salamanders, along the shoreline," Zelazny said. "And we found that that was being caused by a botulism virus."

It's also possible that another naturally-occurring species may have stolen the oxygen these gizzard shad needed to survive: "microcystis" - more commonly known as blue-green algae.

Zelazny said, "What happens is, as these algae die off later in the year, everything settles to the bottom of the lake. And then during the wintertime, it consumes the oxygen."

The DEC relies on residents, especially those who live along Lake Erie, to report dying fish and wildlife. If biologists can get a specimen while it's still somewhat alive, that's what allows them to get samples, run tests, and find out whether we're dealing with disease, toxins or, as in this case, nature just taking its course.