OH: Spawn stress, weather woes led to fish kill

Sandusky, Ohio – The walleye kills that have occurred over
several recent weeks on western Lake Erie numbered “in the
thousands,” will have an insignificant impact on the lake’s current
walleye stock of more than 21 million fish, and likely can be
blamed on spawning stress in the prolonged nasty weather this
spring.

Those are the conclusions of the state’s top Lake Erie fish
authority, Roger Knight, of the DNR Division of Wildlife.

“We’re dealing with thousands of (dead) fish, not hundreds of
thousands or millions,” said Knight. He also noted that Lake Erie
walleye are safe to eat.

In fact, the fish-kill losses might not come near the numbers of
walleye that anglers would have caught and killed during a normal
jig-and-minnow fishing season in April and early May, most of which
largely was canceled by storms.

Knight, Lake Erie program coordinator for the Division of Wildlife,
said up to 30 percent of the lake’s walleye stock is lost to
natural causes every year. The dead walleye mostly are
20-to-24-inch males, and most of the kill has been concentrated
between the waters off Davis-Besse Nuclear Power Station and on
northeast to the Bass Islands, Knight said. The kill-zone lies
mainly in the classic reef complex where many fish spawn.

“We may never know, exactly,” said Knight about the cause. “But I
think that the event is behind us. We’re not seeing (many) new dead
fish.

“It was an unusually cold, stormy spring,” explained Knight. As a
result the spawning cycle was longer than normal, meaning that fish
were forced to remain on shallow reef tops for abnormally long
periods.

“They get pretty beat up on the reefs,” he said. Couple such storm
and wind abuse with the energy and physical stresses of spawning
activity, and the plausibility factor of such a fish-kill scenario
takes center stage.

The researcher discounted a disease outbreak as a reason for the
kill, including viral hemorrhagic septicemia, which is present in
the lake and has caused large kills of freshwater drum, or
sheepshead, in recent years. Six walleye samples from the recent
kill were analyzed at the University of Toledo’s Lake Erie Center
in Oregon and no VHS was found.

Knight said he flew over the kill zone about 20 days ago and “never
did see a big mass” of dead walleyes. He found maybe “a couple
dozen fish,” a happenstance that is possible any given day, he
added.

The biologist also discounted rampant lakefront rumors that Ohio or
Ontario commercial fishermen were behind the kill. This is a common
excuse for all of the lake’s ills in the minds of some individuals.
One rumor that Ohio trapnetters had slit walleye throats – they are
not allowed to keep or sell walleye – is unsubstantiated, Knight
said. Trapnetters are targeting mostly white perch and yellow
perch.

For one thing trapnetting is backbreaking, time-intensive work and
netters hardly would waste time handling and killing fish that they
cannot turn into money and otherwise easily can release, according
to the biologist. And if careless Canadian gillnetters were to
blame – they can keep and sell walleye up there – why would they
throw away such quantities of big-money fish, and why did dead fish
not show signs of gillnet damage?

“You’d be seeing gillnet rings around their heads,” Knight
said.

Many dead fish had no gills left – a typical sign of feeding by
gulls. Gulls go for the soft parts of a dead fish first, and gills
are an early initial target, such that fish are nearly beheaded by
the pecking and feeding. On his fish-kill survey flight, “every
dead fish had a gull on it,” Knight said.

That said, the biologist noted the crummy spring weather, some of
the worst in memory, has left little hope for a decent walleye
hatch this spring. The weather also has ruined the spring
fishing.

“What we need is two weeks of decent weather to get the bite
settled,” Knight said. “Then everybody can go fishing.”

Reprinted by permission of The Blade of Toledo.

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