Salmon cuts on the way
Lansing — An inter-agency Lake Michigan salmon management group is proposing a 60-percent lake wide chinook stocking reduction for 2017 amid the continued decline of both salmon and alewives.
The group, comprised of tribal and government fisheries managers from several states, tracks predator and prey fish populations and follows a set of previously agreed-upon actions based on the ratio of chinook to alewives in the lake.
Lake managers agreed to cut stocking if that ratio reaches .10 – or when biomass of chinook exceed 10 percent of alewife biomass – the threshold at which Lake Huron’s alewife and salmon populations crashed in 2003.
The group cut Lake Michigan chinook stocking in 2013, the same year a hot summer reduced natural reproduction, and the ratio decreased to .08 in 2014, based on the data analyzed last year. The ratio for 2015 came in at .108, and researchers believe the increase is tied to alewives populations decreasing at a faster rate than salmon, DNR fisheries biologist Randy Claramunt told Michigan Outdoor News.
“Salmon biomass and abundance has been decreasing dramatically … especially the last three years,” he said, adding that researchers believe a shift in prey fish populations is behind the trend.
A comprehensive computer model incorporating most of Lake Michigan’s prey and predator species used by researchers this year shows the dynamic is impacting some species more than others, Claramunt said.
“Basically what we were trying to figure out is why was alewife biomass going down when chinook salmon biomass is going down,” he said. Results showed round gobies are taking over as the primary prey fish species, and chinook and steelhead are reluctant to eat them.
“Lake trout eat a lot of them, followed by brown trout and coho, but chinook and steelhead are more geared toward pelagic prey,” Claramunt said. “We saw a decrease in steelhead growth, condition and abundance as well, but not as dramatic as chinook.”
DNR Lake Michigan basin manager Jay Wesley said citizen advisory committees for lakes Huron and Michigan convened in Clare in late June to discuss the stocking reduction proposal, which would cut chinook plants from about 1.8 million lake wide to roughly 690,000.
Before the 2013 cut, lake managers stocked about 3.3 million chinook annually, he said.
The estimated biomass of chinook decreased from about 14 million kilograms in 2013 to about 4 million kilograms last year. Alewife biomass plummeted from 149 kilotons in 2013 to 36 kilotons last year, Wesley said.
“We learned a lot from the Lake Huron experience and we’re trying to make changes quickly so we don’t have a loss of our pelagic prey,” he said.
Anglers, meanwhile, have mixed emotions about the latest proposal, said Denny Grinold, government affairs manager for the Michigan Charter Boat Association and chairman of the Lake Michigan Citizens Advisory Committee.
“When you talk about eliminating plants, some view it as apocalyptic,” he said. “The message this may send is worse than the deed itself.”
Grinold said charter boat operators are particularly concerned with how the cuts could impact their businesses. Grinold said he believes most Lake Michigan anglers understand the need behind the cut – to balance predator and prey fish populations – but not everybody believes it’s necessary.
“In reality, the status quo might not be the answer and if we crash the chinook fishery entirely, that’s not acceptable either,” he said, adding that anglers will be able to voice their thoughts concerns about in the coming weeks and months as they learn more about the proposal and reasoning behind it.
“If you follow the science behind it, it says the things we should do, but when emotions are involved … it’s not going to be easy for some people to accept,” he said.
Wesley said the DNR plans to host public meetings about the proposal in July and August, but “we don’t have to make a decision until around September,” before biologists collect eggs for rearing.