Lake Michigan Trout: Prize or Pest

In the Great Lakes System, lake trout are struggling. They sit at the top of the food chain and help manage the population of smaller prey fish. The federal government stocks Lake Michigan with 3 million lake trout every year. But for some reason, lake trout are having trouble producing offspring that survive. Some biologists think that alewives, a Great Lakes invasive species, produce an enzyme that causes a thiamine deficiency in lake trout. Another theory is that the 3 million lake trout stocked in Lake Michigan every year is not enough to engender a self-sustaining population in a lake that used to have 10 million trout.

Yellowstone National Park Lake, however, is teeming with lake trout. They are regarded as a pestilence that must be ruthlessly wiped out.

Why is the government trying so hard to save trout in the Great Lakes and destroy them in Yellowstone Lake?

Yellowstone managers believe that anglers illegally planted Lake Michigan trout in Yellowstone Lake some 13 years ago. Now, 70,000 lake trout are expected to be pulled from the lake this season.

In the Yellowstone ecosystem, lake trout dominate the native cutthroat trout, which in turn threatens grizzly bears, bald eagles, cougars, loons, and osprey who rely on the stream-spawning cutthroat.

The National Park Service's solution is to aggressively fish lake trout six months a year. Fish are clubbed or punched in the head if they're still alive, gutted, and dumped back into the lake to keep the nutrients in the system. They're not even kept for food because most are too small or too rotten by the time the nets are pulled from the water. At this point, Yellowstone managers hold no hope of eradicating the population; they spend $400,000 a year to control the lake trout population in order to give the cutthroat trout a chance.
Picture: Fishing crew toss the gutted lake trout back into Yellowstone Lake.

Click here to read the full article on Lake Michigan trout in Yellowstone Lake.

Invasive species wreak havoc on the ecosystem to which they have been introduced. The Great Lakes have over 180 invasive species, costing us billions of dollars in damage and management every year. Click here to read more about invasive species.