Great Bear Lake home of monster fish of mythic proportionsGreat Bear Lake monster fish
By Ed Struzik, edmontonjournal.com
But when she and her colleagues netted a 23-kilogram lake trout in Great Bear Lake in the Northwest Territories recently, she admits she was a bit wide-eyed when the fish appeared to be nearly as long as she is tall, which is not small.
“It was a big fish,” says Chavarie who more than capable of pulling her weight. “But the Dene people in DeLine, the village on the shore of Great Bear, have caught fish that are much bigger than that one.”
That may sound like a tall tale. The biggest lake trout in Alberta, which was caught in Cold Lake more than 80 years ago, was about the same size as the one Chavarie netted. Alaska’s biggest lake trout came close, but it was just 21 kilograms.
Great Bear is known for its monster fish. In 2000 American sportsman Matt Cornell’s 35.7-kilogram behemoth established an angling record that has not been broken since. However, DeLine resident George Kenny got a bigger one three years ago when he netted a 38-kilo fish in the lake near Broken Plate Creek. He says he caught a larger fish the year before, but threw it back in so that it could produce more of the same monsters.
Up until recently, Iceland’s Lake Thingvallavatn was considered to be most special among the world’s polar lakes. Not only does it have big char, which lake trout are, it has four anatomically distinct forms of char with different food habits and growth rates. Lake Superior, by way of comparison, has three. Lake Hazen, the biggest lake above the Arctic Circle, has two and recent studies suggest it could have three.
But Chavarie, along with her University of Albert PhD supervisors Bill Tonn and Kim Howland are promising to put Great Bear into the record book with their study of four, and possibly five distinct forms of lake trout that have recently been discovered living there. Four of them are found in shallow water. The fifth suspect was found deeper down.
Being 320 kilometres long, 175 km wide and 450 metres deep in some places, Great Bear is the eight largest lake in the world and the largest that lies entirely within Canada.
Like most Arctic lakes, it was created thousands of years ago when the continental ice sheets retreated. Lake trout and other forms of char living in recently deglaciated regions gradually moved in to exploit the new source of food that became available.
With very little competition for these new food resources, the fish ended up dividing the lake up like a pie. While some became small bottom feeders, others became big bottom feeders. Monster fish such as the one that Chavarie and George Kenny caught became incredibly fast-growing fish eaters. All of them, more or less, exploited plankton.
Unlike most other fish in crowded southern lakes where competition for food is intense and where the ability to specialize is limited, Great Bear’s trout could be on the same kind of fast-forward evolutionary trajectory that has been seen in Darwin’s Finch in the Ecuadorean Galapagos. Finches there have evolved to have a smaller beak within two decades.
Great Bear’s fish have not been evolving nearly as fast as those finch. But in a relatively short period of time, they have morphed into these anatomically distinct forms with different food preferences and growth rates. Although they already exhibit some genetic differences, they can still interbreed.
This kind of diversity is extremely important because it could supply these fish with a range of evolutionary options that allow them to adapt to a rapidly changing Arctic world, which is warming faster than any other place on the planet.
That ability to adapt may not help lake trout in the big lakes of Alberta, Saskatchewan and other parts of southern Canada and the United States, however.
University of Alberta scientist David Schindler believes that big shallower lakes like Lake Athabasca on the Alberta/Saskatchewan border, which produced the world’s biggest lake trout in 1961 on the Saskatchewan side, may not be able to sustain these fish in the future if water temperatures continue to rise.
In the 1990s, he and others demonstrated that lake trout do best in temperatures ranging between 8C and 12C. A temperature of 23C is lethal for lake trout, as it is for the closely related bull trout, Alberta’s most famous fish.
“The opossum shrimp — Mysis relicta — the main food for small lake trout, have similar temperature tolerances as well,” he points out, “It is probably no coincidence that they are both glacial relicts that co-evolved, so where one is found, so is the other.”
Cold water fish such as these can be sneaky, says Schindler. They have been known to move into warm water to feed for short periods of time before retreating back to the deep to cool off.
“But I suspect we will lose some of our biggest lake trout lakes, such as those that do not stratify in summer because they are so large and shallow that they don’t form a thermocline – that steep temperature gradient which separates the upper mixed layer of warmer water from the colder water below.
“Lake trout survive because the lakes never reach temperatures above 17-18C,” he adds. “But with climate warming, they will probably exceed 23C and there will be fish kills in places like Lake Athabasca and other large lakes in southern NWT/northern Alberta and Saskatchewan.”
Being as deep as it is, Great Bear in not going to warm as fast as Lake Athabasca or Cold Lake for that matter. But Howland says young fish in the lake could be at risk if they are forced to move out of the near shore shallows into deeper waters occupied by adults.
“That’s why it’s important to keep monitoring the situation and to ensure that harvest rates are sustainable.”
Currently, the community of DeLine, which is participating in the study, harvests about 3,000 fish each year.
Former DeLine chief Walter Bayha says the fact that Great Bear is still home to “Grandfather” fish such as these that can live up to 50 years or more is a sign that all is still well in this part of the world.
“People here take great pride in the fact that this one of the last place on Earth where there are still fish as big and healthy as these fish are. It’s important that it stay that way.”
Chavarie says she got the idea of going into this field of science just as the cod fishery began to collapse.
“When I grew up in Gaspé, I often went cod fishing with my father who was a biologist with Parks Canada. When I was nine, we could catch more cod than we needed; there were so many. But five years later, may father and I went out fishing one day and we caught only one fish after several hours of trying. When I go into fishing communities like DeLine, I tell them that. When change happens, it can happen very fast.”
Friday, 12 March 2010
Great Slave Lake creature -possible identity?
The first documented sighting I could find was this but no date :On a moonlit night Antoine Michel and his wife where returning to their home from a caribou hunt across the lake. They saw what appeared to be a large rock sticking up out of the water and navigated the boat around it. The rock sank below the surface as they passed and waves from it rocked the boat. (Unusual behaviour for a rock.)
In the mid 90’s there was a recovery operation to locate the body of a man who had fallen through the ice. Two of the three divers reported they saw a large animal which was described by one of the divers as having an alligator like body with a head like that of a pike.
In 2004 Roman Catholic priest, Father Jim Lynn, looked out from his home on the shores of the Great Slave Lake, near
'It was like the head of a dragon'