Where have the fish gone?
That's the question being asked by Lake Michigan charter boat captains, who are finding that their charters are catching bigger fish - but fewer of them - from this year's Chinook salmon schools. And while it's easy to focus on the positive aspects brought on by bigger fish, many Great Lakes fishing experts are worrying that the Chinook salmon fishing industry - the biggest sport fishing draw in Lake Michigan - might be veering toward a near-collapse.
Their worries aren't unfounded: a similar trend of big fish and smaller schools plagued Lake Huron in 2003, right before its Chinook salmon fishing industry tumbled from prominence. If the same is about to happen in Lake Michigan, then fishing boat captains may be in danger of losing their livelihoods.
From the looks of the Lake Michigan situation, the salmon trends are almost the same as they were in Lake Huron a decade ago. The problem relates back to baitfish - particularly the Chinook salmon's choice diet of the alewife - which have been backed into a hypothetical corner due to numerous predatory issues.
First of all, zebra mussels, which have expanded in prominence throughout the Great Lakes over the past few decades, are disrupting baitfish life cycles. While mussels don't eat baitfish, they do consume the same nutrients that baitfish like the alewife depend upon to live. In other words, mussels are disrupting the food chain, and that disruption is now impacting the Chinook salmon populations in the lakes because the numbers of baitfish, as well as the rapidity of their reproduction and proliferation, have declined.
Another issue is that neither Chinook salmon, nor the alewife they eat, are native to the Great Lakes. The states surrounding the lakes customarily stock them with Chinook salmon each year, and in an ideal food chain, the alewife would be reproducing fast enough to feed the salmon population. Since zebra mussels are disrupting the food chain, however, alewife are having difficulty rebuilding their populations, and since salmon eat the alewife so rapidly, the baitfish could soon be extinguished from Lake Michigan entirely.
By looking at alewife ages, scientists have essentially proven that Chinook salmon are eating their way through the baitfish population.
Normally, salmon go after the older alewife because they are bigger. This year, scientists have found that the average alewife age is much younger than usual, suggesting that the older fish have now been wiped out, leaving only the younger ones to feed upon. And since the mussel-indebted dearth of nutrients means that fewer alewife are reaching a healthy old age, it also means that the current trend, if allowed to continue, will lead to what anglers are calling an "alewife crash."
A crash of alewife would essentially mean the crash of the Lake Michigan Chinook salmon industry, which would in turn be a major economic blow for the surrounding states. However, such a crash would also give native baitfish and native species a chance to swim to the forefront of the Great Lakes fishing industry. But since reports indicate that Lake Huron lost 75 percent of its fishing draw potential after the 2003 salmon debacle, the future looks bleak for Lake Michigan as a salmon fisherman's destination.