Cormorants damaging fish populations
By Mary Drier, For the Tribune Published 6:05 am EST, Saturday, February 29, 2020
UPPER THUMB — There is another culprit in the decline of the fish population in the Great Lakes other than commercial fisheries, according to the U.S. Fish and Wildlife Service.
It is estimated there are about 230,000 double-crested cormorants around the Great Lakes, each eating an estimated 1.3 to 1.6 pounds of fish a day. That equals more than 77 million pounds of fish per year, according to a report from the Michigan Department of Natural Resources.
The birds eat minnows, alewives, shad, round gobies, other prey-fish, and they also devour significant numbers of yellow perch, stocked trout, salmon, walleye, pike, and panfish.
Around the Great Lakes, prey-fish populations are already greatly reduced, and in Lake Huron they are reduced by 80-90%.
“Cormorants are uncontrolled and wreaking havoc on our Great Lakes," said Lakon Williams, who manages the Bay Port Fish Company. "Since the Zebra Mussel invasion, the lakes and the water are cleaner than ever."
“Cormorants are a sight feeder that can see up to 40 feet in the water," she said. "With the water being clearer fish have no where to hide."
“When going out fishing on Saginaw Bay, it is common to see a black swarm of cormorants gorging themselves. It is a horrific sight to see, these birds need population controls,” she added.
Double-crested cormorants are an equal opportunity predator. They eat whatever they can catch in their beak. Cormorants have been recorded schooling fish up into shallower water and then they take turns diving to feed. They have been noted to dive up to 150 feet and are routinely diving 30 feet or more to feed in the Great Lakes.
MDNR research has established a link between cormorants preying on fish populations and their decline in the Saginaw Bay, the Great Lakes, and the Les Cheneaux perch fishery.
Stocking of trout and salmon is impractical when cormorant numbers at stocking sites become excessive, and this continues to happen throughout lakes Michigan and Huron.
“We desperately need cormorant control again,” said Don Kain, who is the lead administrator for the Facebook group “Save Our Fish,” focusing on environmental issues that affects fisheries. “I believe this to be a huge problem. I don't want all cormorants killed, but we clearly need population control.”