Zebra mussels put snag in walleye fishing

[Spiel]

Zebra mussels put snag in walleye fishing

 

April 24, 2008 / intelligencer.ca

 

Where have all the walleye gone?

 

Ron Skevington has some theories.

 

As a lifelong angler, he believes populations are still abundant in the Bay of Quinte, even 15 years after habitat-killing zebra mussels were first spotted in the area. They're now just harder to find.

 

"When I first moved here, everybody was saying there were no walleye," said Skevington, a Lake Erie-bred angler who moved to Belleville seven years ago to open Skevy's Outdoor Specialties, a fishing supply store. "But I took the methods I was taught and applied them on the Bay of Quinte and I had no problem catching walleye. Guys who were fishing their old ways weren't catching walleye and said there was no fish here."

 

Anglers and researchers agree that zebra mussels, an invasive species that first came to North America 20 years ago, have altered fish populations across the continent, including in the Bay of Quinte.

 

Most fish populations have shrunk due to the mussels consuming plankton - tiny organisms living in the water that fish need to eat. But when plankton levels are reduced, water becomes more clear, allowing more light to penetrate to a lake's floor. That leads to more plant growth in water.

 

Skevington advises anglers to look for weed beds and that's where you'll find walleye. It's a lesson he learned on Lake Erie, one of the first Great Lakes to be infested with zebra mussels.

 

"When we got more weed beds, walleye and bass populations started to come back and we found we had to fish for walleye in a different method," he said. "Walleye are predator fish, so they were tucking themselves in weed beds and chasing minnows where they were going to hide."

 

Although Skevington believes walleye are making a comeback, Ministry of Natural Resources researchers aren't so sure.

 

Beth Brownson, an MNR invasive species biologist based in Peterborough, said the overall environmental harm zebra mussels cause overrides any temporary rise in population for a particular species.

 

The most troubling thing about them, she said, is they cause already-contaminated environments to get worse.

 

"They concentrate (contaminates) in their bodies," she said. "If I'm a fish or a bird and I eat a zebra mussel I'll get way more contamination in my system than from eating other food sources."

 

This is the 20th anniversary of zebra mussels' arrival to North America, but Brownson said it's nothing to celebrate. Since first appearing in Lake St. Clair in 1988, apparently from ocean-going commercial vessels, they have spread across the Great Lakes, complicating environmental clean up efforts.

 

It didn't take long for zebra mussels, known to multiply quickly, to find their way to the Bay of Quinte where shallow conditions are ideal for their growth. A Department of Fisheries and Oceans report said they were first spotted in the bay in 1993.

 

Jeff Borisko, implementation manager for the Bay of Quinte Remedial Action Plan, an organization in charge of cleaning up the bay, said a Department of Fisheries and Oceans program to monitor zebra mussel growth seems to indicate it's stable.

 

But he also said it's important not to jump to conclusions. Researchers have made the conclusion by counting zebra mussels at four different checkpoints year after year. But the number of zebra mussels in other parts of the bay could be quite different, he said. "The bottom line is the ecosystem has changed and it has to be managed differently," he said. "They're here to stay."

 

And now that scientists have pinpointed the problems of zebra mussels, the more challenging task of curtailing them has begun.

 

"Unfortunately we don't have a silver bullet to eradicate them and we probably never will," Brownson said. "But we hope to come up with some management solutions."

 

She said the ministry is studying programs that helped reduce other invasive species such as sea lamprey, an eel-like fish. In this case, barriers were put in streams to prevent the species from travelling in order to spawn.

 

Other invasive species have been reduced through biological control agents - in other words, chemicals that kill a particular species but cause no other ill effects on the ecosystem.

 

But such things are tough to invent.

 

"A biological control agent may be found for zebra mussels," Brownson said. "But at this point, we don't have it."

 

In the meantime, the ministry hopes the public will do its part. Brownson said education programs to teach people to wash their boats after coming out of the water are on the go. Zebra mussels get around by attaching to the bottom of boats and can even grow on seaweed.

 

She also advises anglers to not dump bait buckets in water. Though few people realize it, zebra mussels can reproduce in small pools. By dumping your bait bucket back in the water, you may be releasing zebra mussel eggs that you can't even see.

 

If more people follow these instructions, zebra mussel growth will level off, she said.

 

Skevington believes that levelling off is already happening on the bay.

 

He said a boat at a local dock used to have a problem with zebra mussels. A rope attached to the vessel would always be covered with them.

 

"Last year we noticed that rope had none on it," he said. "And the docks that normally have zebra mussels all over the legs had none on it," he said. "The comments from a lot of fishers was, 'zebra mussels seem to be decreasing.'"