I was in the medical lab, sent there by the doctor as part of my yearly physical, when I realized I’d forgotten to bring some reading material. I turned to the book rack fervently hoping to find something other than Woman’s World or Homes and Gardens. I was in luck. Smack dab in the middle of the rack was an issue of Outdoor Canada, on its cover a picture of a beaming fisherman hoisting a lake trout aloft overlaid with the titles of the articles on offer inside: Secret New Tactics Walleye Guide 2011; MANITOBA ADVENTURE: A FIRST-TIMER’S FLY-IN; STOP CLIMATE CHANGE NOW!; HOW TO HUNT TURKEYS.
Wait a damn minute, I thought. STOP CLIMATE CHANGE NOW! – what is an article with that title doing in the midst of all those huntin’ and fishin’ pieces?
I flipped through the pages and discovered THE BOILING POINT on page 71. Its author, David Schindler, besides being an angler, is a Rhodes Scholar, the author of over 300 scientific publications, a professor of ecology at the University of Alberta, an officer of the Order of Canada, a recipient of Canada’s highest scientific honour, the Gerhard Herzog Gold Medal for Science and Engineering, and last year’s winner of the LaRoe Prize from the International Society of Conservation Biology.
No lightweight, this dude, I thought.
I read on in earnest, suspecting he would have something important to say. And, he did, in spades.
Dr. Schindler has done much work on the effects of rising temperatures on lakes and has concluded that global climate change, specifically, our warming climate, is threatening the fisheries and aquatic life in Canada’s lakes in many ways. Lakes are layered things. These layers are marked by zones of abrupt temperature change called thermoclines. Currently, wrote Schindler, this country’s best lake trout fisheries are large, windswept bodies of water like Wollaston Lake and Lake Athabasca. These water bodies reach temperatures of 18 C to 19 C in midsummer and are too shallow to have much of a thermocline.
Lake trout, it seems, die when the water temperatures reach 23.5 C. Since the 1960s, when he began recording temperature rise in many of these lakes, they have risen by 2 C. Over the next several decades, Schindler, and other respected scientists, predict these waters will experience a rise of 6 C, which will wipe out lakers and many other temperature intolerant species. In some lakes the niches vacated by these species will be filled by warm water species such as pike, but Schindler hastens to point out that many of our lakes have no warm water replacements.
On nutrient loaded lakes like Lake Winnipeg, writes Schindler, it’s not uncommon to see shorelines littered with dead whitefish and ciscoes, either in late summer or just after ice out. These fish kills are a result of suffocation, as oxygen is used up by the decomposition of excess algal blooms.
Schindler confidently predicts that these fish kills will become far more frequent as the water warms, and if this message isn’t scary enough, he argues that there is no reason to expect that fish kills will be confined to lakes alone. There have already been trout kills on Alberta’s world renowned Bow River and many of that province’s southern streams, prompting closures by Alberta Sustainable Resource Development several times in the last decade. Oxygen is less soluble in warm water, and like the fish in Lake Winnipeg, the Bow river rainbow trout suffocated and died.
Reading this made me recall the problems experienced by the great, but diminishing runs, of Fraser River Sockeye. For over a decade fisheries scientists and fisheries managers working for Fisheries and Oceans Canada, have fingered rising temperature regimes as a key factor in the disappearance of large chunks of the once magnificently abundant runs sockeye to Canada’s greatest salmon river. The predation on sockeye juveniles by mackerel drawn to our warming coastal waters, and the diminishing cooling effect of shrinking glaciers are two other factors exacerbating the plight of salmon that can be attributed to climate change.
“We can probably expect a slow disappearance of the most temperature-intolerant species, such as Arctic grayling and bull, brook and cutthroat trout,” writes Schindler.
I was distracted from the article briefly by the weather related conversation of two old guys sitting next to me.
One complained of the cold summer.
“Well, so much for all that talk about global warming,” said the other.
More on climate change next week…..