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.