This past Thursday, we had Mike Donofrio, the fisheries team leader from the WDNR come in the talk with us on what he is currently involved with regarding lake sturgeon. The DNR is measuring the lake sturgeon spawning fidelity to Green Bay rivers – where they spawn and whether it is the same location as where they hatched. They wanted to do some research with genetic structuring to create a genetic tree of populations and genetic similarities. Of the total lake sturgeon population in Lake Michigan, 75% of their spawning activity occurs in the bay of Green Bay, and 50% of the total occurs just in the Menominee River.
The process of tracking the species begins by anchoring a sonic transmitter and receiver into the sediment of each river. This transmitter has a cone-shaped signal whose radius reaches both banks of said river. It has a Bluetooth that accounts for each passing fish, and this is how each fish is noted. Later on, they go back through the data to make sure a single fish hasn’t passed more than once, and therefore counted more than once. They track the fish by using a VEMCO tag, inserted in the fish to track movement. Between 2011 and 2014, during the months of April & May, they capture the lake sturgeon by electroshocking and using dipnets.
So far they’ve found that many fish, when not spawning, are transitory between river systems throughout their life, and many do not report back to their river of origin. Some actually stay within the same river throughout the year. Usually it was the males and not females who would return to spawn. Data will continue to be collected on this subject for some time yet.