Stressers changing fish

[Spiel]

Stressers changing fish

 

 

June 4th, 2009

Michael Woods / The Kingston Whig-Standard

 

 

Lake Ontario getting warmer

 

Lake Ontario is accumulating what one expert calls “stressers,” factors that may affect fish perhaps more than some species can handle.

 

“It’s changing the fish communities from colder fish communities to warmer ones,” warns John Casselman. “Different species now are becoming more abundant.

 

“I’ve seen this dramatic change.”

 

Casselman, a professor emeritus of biology at Queen’s University, was honoured by the Great Lakes Fishery Commission Tuesday at the beginning of its two-day conference in Kingston.

 

The organization, which co-ordinates fishery research and ecosystem management in the Great Lakes, awarded Casselman the Jack Christie- Ken Loftus award for distinguished scientific contributions toward understanding Great Lakes ecosystems.

 

Casselman said climate change is already having a dramatic effect. In the summer months, Lake Ontario’s temperature is two to five degrees warmer than the air.

 

“It isn’t just the ambient heat, but it’s the solar energy,” he said. “That energy that’s coming in is being trapped in the water more than it is on land.”

 

As a result, warm-water fish such as sunfish and bass are in abundance, while cold-water fish such as lake trout and whitefish are suffering.

 

Casselman said fishers should adjust their harvest accordingly.

 

“The warm-water fish are increasing in massive numbers, so we should be exploiting them and using them.”

 

In recent work with Natural Resources Canada, Casselman said Lake Ontario’s temperature is set to increase four degrees over the next 100 years if climate change isn’t addressed.

 

“We’ve seen a one and a half degree change in the past 20 years, and we know there’s two degrees programmed in, even if we solve climate change right now.”

 

Casselman said one way to fight climate change is to make local fish more readily available.

 

“Whenever I get a piece of fish it’s been flown from Honduras,” he said. “It’s flown 1,500 miles to get on my plate when I’ve got excellent fish out my front door that don’t cost me carbon units.”

 

When Casselman began his research career 40 years ago, the Lake Ontario fishery was much different than it is today.

 

“It used to be essentially a big commercial fishery,” he said. “At one time in the 1950s, they were still harvesting probably a thousand tonnes of fish from Lake Ontario in commercial fisheries.”

 

With the growth of recreational fisheries, though, he’s seen quite a shift.

 

“You had to give up one because of the other because the lake only produces so much fish,” he said.

 

“We’ve been able to communicate to recreational fishers that they can’t harvest like they used to. As a result, catch and release has become a very important aspect of fishery management.”

 

Casselman, who worked for the Ministry of Natural Resources before retiring and joining Queen’s, chairs a working group on the American eel, an Atlantic seaboard fish that has all but disappeared from Lake Ontario, in part because it is being killed in canals, dams and turbines.

 

“When we Europeans arrived on these shores 400 years ago, half the inshore fish biomass — the weight of fish in shore down to 30 feet deep — was the American eel.

 

“Now they’re gone. This one fish, if you look at it carefully, is showing all of the stressers that we’re placing on these very important waters.”

 

“We have to do something about this.”