Climate change will halve the Canadian trout population: study

[Spiel]

Climate change will halve the Canadian trout population: study

 

Monday August 15/2011

http://www.thestar.com/

Research suggests that climate change will make it harder and harder for anglers to find a good trout stream in the future.

An American study published Monday says warmer water, altered stream flows and changes in the life cycle of bugs will reduce the number of streams in the United States that are suitable for all kinds of trout by nearly half over the next 70 years.Research suggests that climate change will make it harder and harder for anglers to find a good trout stream in the future.

 

And while Canada won’t be hit as hard, fisherfolk north of the border will also notice a decline in one of the most prized species of game fish.

 

“The fundamental prophesies operating, in terms of the temperature of the flow, those should be fairly universal,” said Seth Wenger, a staff scientist at the conservation group Trout Unlimited. His paper was published in the Proceedings of the National Academy of Sciences.

 

Wenger looked at how the temperature of water in suitable trout streams is projected to change over the coming decades and combined that with what is known about how stream flows are expected to shift.

 

With more precipitation predicted to fall as rain instead of snow and with spring coming earlier, streams will probably reach high-water marks earlier in the year. That could see trout eggs prematurely scoured from the gravelly stream beds they need to hatch.

 

Climate change is also expected to change the behaviour of other species that affect trout. If the bugs the fish love to eat hatch at a different time it could throw off the delicate timing of freshwater environments.

 

Cutthroat and brook trout are expected to come off the worst. Wenger said brook trout could lose up to three-quarters of their habitat in the western United States by 2080.

 

Rainbows could lose more than a third of their streams and browns nearly one-half.

 

Canadian streams, generally colder than American streams, won’t suffer as badly, he suggested. In fact, some high-altitude streams may warm up enough to actually become trout habitat.

 

“We may see upstream migration and colonization of habitats that are currently marginal for them.”

 

But the overall trend is the same.

 

“In the low elevations, I would expect to see some loss of habitat for sure,” said Wenger. I would expect in parts of Eastern Canada we would see declines in brook trout as well. Brook trout are going to have a very hard time of it in the future.”

 

And the outlook for bull trout —Alberta’s provincial fish and a species of special concern under provincial legislation — is worse than most.

 

“Bull trout are by far the most climate-sensitive of the fish we looked at,” Wenger said. “The predictions for them are very dire. They’ll be better up in Canada, but I would expect severe difficulties for them.”

 

Streams are already warming up as the climate slowly shifts, although that hasn’t yet produced any noticeable effects on trout numbers, he added.

 

“Trout are flexible and they will adapt to the extent they can. But at a certain point, you get a combination of conditions getting worse for them and then an event happens that leads to a rapid change.”

 

[Loadman]

this better not happen..