According to biologists, there are a number of factors:
Competition from non-native species. Grayling in Michigan likely evolved with the state’s other native salmonid—the brook trout. But the introduction of rainbow and brown trout likely spelled doom for the native fish.
Habitat. This is a no-brainer. Where grayling live and thrive today throughout the north country of Canada and Alaska, habitat is virtually pristine. In the northern Lower Penninsula of Michigan, the habitat has changed dramatically from the time grayling provided both sport and sustenance to a growing state. Logging and mining have taken their toll on the region’s watersheds. Thankfully, thanks to long-term efforts to protect and improve the nation’s water quality, habitat is once again more welcoming to grayling.
Imprinting. This may be the trickiest factor. Learning from somewhat successful efforts in Montana, Michigan’s fisheries experts are now working to restore grayling to high-quality watersheds by incubating the eyed, or fertilized eggs, in the target stream. In other words, grayling tend to do better in the environment if they can imprint on the chemical makeup of a single river or stream as they develop and even before they hatch.
Here’s more background from the Muskegon River Watershed Assembly:
It is easy to imagine why a reintroduction holds value. The Arctic Grayling, with its sail-like dorsal fin and purple/gray hue, is a one of a kind fish that displays features you would expect to see in a marine fish. It is an iconic species and in the lower 48 states is native to only Michigan and Montana. It also holds cultural importance to Tribal nations and Native people, as well as, a historical significance to the unspoiled wilderness of Michigan’s heritage.
But why now? And haven’t we done this before and failed? These questions are valid, and the simple answer is…”the current initiative is different”. Since the last stocking in the 1990’s there is a better chance of success because of new information from Montana, a better understanding of Michigan rivers, and a focused research effort to understand the key river conditions needed for sustainable grayling populations. It is exciting that this effort may have implications for the Muskegon River watershed.
Illustration: Wikimedia Commons. Check out the 20 minute video.