Lake Huron salmon numbers fall; fish go to Canada

The San Jose Mercury News provides this update on the fate of Lake Huron salmon:

Five years ago, about 15 percent of the chinook salmon that biologists sampled from Lake Huron were wild fish, and the other 85 percent were produced by hatcheries in Michigan. Today, that number has turned around, with 20 percent of the fish coming from hatcheries and 80 percent from salmon that run up tributary streams to produce the next generation without human help.

In most parts of the country that would be good news. But not on Lake Huron, where the glut of salmon has overwhelmed the alewives that once formed their prey base. And most of the salmon are produced not by Michigan streams but in rivers on the Canadian side of the lake 80 to 100 miles away, which means that in August, the adult chinooks head back to their native streams to spawn and largely disappear from the Michigan side.

When there was a similar decline in prey fish in the late 1990s, biologists responded by reducing the number of salmon they stocked. But with most of the fish now being produced naturally in rivers in Canada, there is no way to shut off the spigot. The actual number of salmon in Lake Huron a few years ago might have been two or three times the official estimate of 4 million to 5 million, Johnson said.

Johnson said there are several possible scenarios for the future of Lake Huron, all of which are largely out of the hands of biologists. Decreased predation by salmon and mild winters could result in a resurgence of alewives, followed by a resurgence of salmon in boom-and-bust cycles. The DNR is considering reintroducing lake herring, a native prey and food fish that was largely wiped out by the changes in recent decades. This would lead to lake trout as the primary sport fish, with salmon playing a lesser role. Johnson said that's what happened in Lake Superior when the lake trout was brought back from near-extinction.

"Lake Huron really is a lot like Lake Superior,'' Johnson said. "Most of it is very deep and very cold, with relatively few shallow shelf areas. That's why Huron is much less productive than Lake Michigan.''