Claire Corlett

Fish Food, Fish Tanks, and More
What’s really going on with salmon in Lake Michigan?

What’s really going on with salmon in Lake Michigan?


What’s really going on with salmon in Lake
Michigan? It’s been all over the news – the up-and-down
dynamic of Chinook salmon in Lake Michigan. One week you’re hearing that no anglers
are catching kings and the next week the story has shifted to report 20-pound fish with their
stomachs full of alewives. What does all this mean? These developments are just one more twist
in the bigger story of the relationship between Chinook salmon and alewives in Lake Michigan
– a story that stretches back to the 1960s. Most people know how these two species came
to be married together – a significant abundance of the invasive alewives were wreaking havoc
on Great Lakes beaches and non-native Chinook salmon were brought in to help control the
situation. The management was simple at first – for
the first 20 years we would stock more fish and anglers caught more fish. Then the productivity started to change in
the lake, mostly due to invasive species like quagga and zebra mussels. This totally changed the food web and sent
a ripple effect through the Great Lakes and the sportfishing industry. These filter-feeding mussels target the same
food alewives eat and rather quickly the lake’s structure was turned on its head. Thirty years of data collected by the DNR
and partner agencies show the lowest abundance of alewives since sampling began. There are very few options to implement before
a complete transformation in the fishery occurs. What can the DNR do? Much has been asked of the department – and
other state and federal natural resource agencies along Lake Michigan’s coast – to rectify
the current Chinook salmon trend. Here are some options and their feasibility: Rear and stock alewives. Lake Michigan is huge…so the number of forage
fish in a waterbody of that size is also huge. If the DNR put all of its rearing efforts
into alewives, it would only produce enough fish to feed Lake Michigan’s predators for
less than 2 days. Maintain current or increase Chinook salmon
stocking levels. The DNR feels this is a risky move as doing
so would increase the risk of an alewife collapse. Lake Michigan already has an improper balance
of alewives to Chinook salmon and stocking more Chinooks could decimate the alewife population
even further. Additionally, wild Chinook salmon have been
increasing their numbers and show that the fishery is less dependent on stocked fish. More than 60 percent of the Chinook salmon
being caught by anglers in Lake Michigan are naturally reproducing fish. Decrease Chinook salmon stocking levels. Done previously by the department, this action
would allow for a better balance between predators (Chinook salmon) and prey (alewives). Resources not used to rear and stock Chinook
salmon would be shifted to other fish species to contribute to Michigan’s overall diversity. Decrease lake trout stocking levels. Rehabilitation of native lake trout has been
an ongoing project for the last 60 years. But lake trout are another top predator of
alewives and will capitalize on their availability, thus taking away the Chinook salmon’s only
food option. It should be noted that Chinook salmon ONLY
eat alewives, while other top predators – including lake trout – have a more diverse diet. Fight against the invasive mussels. As sad as it sounds, there is little that
can be done about the current population of zebra and quagga mussels found in Lake Michigan. Their numbers likely fall in the billions. At this point all that can be done is to protect
against additional invasive species from becoming established in any of Michigan’s waters. What can you do? Continue to fish! But rather than thinking about Lake Michigan
the way it was five, 10 or 20 years ago – go out and experience Lake Michigan now. It could be really different, but also fun. The DNR is continuously working to properly
manage Chinook salmon and other fisheries in Lake Michigan. For more information on this – and other
issues – visit Michigan.gov/fishing.

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