Scientists have been worried about the herring population in Lake Superior recently. In fact, last year they warned it might collapse.
Lake Superior is the only one of the Great Lakes with a large population of this native fish.
This fall, new rules protecting herring took effect in Wisconsin and Minnesota and things appear more stable.
But there may still be a big problem lying beneath the surface.
Lake herring are also called cisco. They thrive in Lake Superior like few other places in the world.
Seth Moore is a biologist for the Grand Portage Band of Chippewa Indians. He says that without cisco, the entire lake would suffer.
That’s because cisco is a keystone species.
“So all the other species of both prey and predators that are in that food web change around in their proportions of the lake and you may see very, very long lasting repercussions of the crash of a stock like that,” says Moore.
Cisco was once a product mainly used for animal feed and plant fertilizer.
But Terry Margenau, with the Wisconsin Department of Natural Resources, says about 10 years ago, its eggs became a prized commodity.
“There was a market in Scandinavian countries for the eggs, for the roe, and that of course created a much more aggressive market from the commercial side of this and the annual harvests went up considerably after 2008-2009 in that time period,” he says.
And these new market pressures are causing concern.
Biologist Seth Moore says as long as spawning fish are being targeted, the cisco population will continue to suffer.
“And we’re harvesting them while they’re trying to reproduce, and we’re taking their reproductive products out of them; it just doesn’t seem like a recipe for sustainability in my opinion,” says Moore.
Demand for their eggs is not the only problem that cisco are currently facing. Warmer water temperatures have also been a struggle.
Cisco tend to reproduce best during winters with heavy ice cover on the lake. So the warming climate is reducing the number of young fish.
Balancing protections and business
For these reasons, states are capping the amount of cisco that can be caught.
Now, in Wisconsin, fishermen can only take 15% of the total amount of cisco from state waters. Minnesota has been a bit more conservative, limiting its fisheries to a 10% catch.
Terry Margenau says these caps are flexible.
“I think we’ve got built-in mechanisms to prevent any overharvest in the long term. If abundance goes up three years from now, the quotas would go up, and similarly if abundance goes down, those numbers would be adjusted down,” he says.
Margenau says the caps should keep the population healthy and the fishing industry content.
But there’s plenty of disagreement going around about these rules. Some commercial fishermen don’t want any regulations at all.
On the other hand, tribal biologist Seth Moore doesn’t think the new laws go far enough.
“My personal opinion is that the more conservative we are, the better likelihood we have of sustainable fish stocks that people can use for recreational or subsistence purposes or commercial purposes," he says. "But our practice in general, across the planet, is to try to push these boundaries too far and we see fish stock collapses worldwide as a result of pushing these boundaries too far.”
Moore says his tribe is now catching far fewer fish than in years past, about half as much, and initially it didn’t go over well with his members.
But he says understanding the research helped them see the threat of a collapse was real, and they ultimately agreed that the restrictions were the right choice for the lake.
Support for this story comes from the Knight Center for Environmental Journalism at Michigan State University.