Lake Sturgeon Spawning Delayed but not Denied

Wisconsin DNR staff capture lake sturgeon for tagging, measuring and spawning. Credit: USFWS

Sturgeon spawning below the Shawano Dam on the Wolf River. Credit: US FWS

BY DOUG ALOISI, GENOA NFH

With the cold temperatures this spring, the crew at the Genoa National Fish Hatchery (NFH) wondered if lake sturgeon spawning would ever commence. Our typical river
walleye brood stock collections start the first week of April when longer daylight hours and warmer river temperatures trigger the walleye to spawn. Lake sturgeon spawning tends to be more temperature dependent with water temperatures usually rising to above 52 degrees Fahrenheit before spawning activity is observed. This usually happens in mid to late April in smaller river systems such as the Wolf River in Wisconsin, and all the way into June for larger river systems connected to the cold waters of the Great Lakes such as the St. Lawrence River in New York and the St.
Clair River in Michigan. In our culture program, lake sturgeon spawning occurs throughout the months of April through late June. It is a frenetic but fun time, packing
and unpacking supplies and equipment, and travelling to such exotic places as Shawano Wisconsin, to Sarnia, Ontario and Massena, New York. The staff is worn down by the end of June, but hopefully feeling satisfied with a large number of lake sturgeon eggs and larvae to care for all summer.

This year’s egg take on the Wolf River will be part of a study to determine contaminant levels in adult and larval lake sturgeon from a number of Great Lakes
tributaries. The Genoa NFH will act as a control for the study, as our water comes from groundwater located 100 feet below our feet at the hatchery site. This groundwater has been warmed by the sun in our 1.5 acre solar pond to stimulate lake sturgeon growth in the summer months. By further enhancing our water supply by adding pure oxygen to our water, our rearing capacity for 6 inch lake sturgeon has expanded from 25,000 fingerlings per year to 48,000 fingerlings per year. Other studies planned for this year are examining growth rates at various temperatures to determine maximum growth of lake sturgeon fingerlings at given water temperatures. We will also soon have plenty of help in the sturgeon building, with our summer staff of two Pathways college student positions joining us and three Youth Conservation Corps high school students also added in to the mix. They will be plugged in to the sturgeon culture program and have an important role as “sturgeon whisperers” helping the larval fish grow and be healthy and fit for the wild come late September while our students will be safely back at school again. We are hopeful that through our efforts another strong year class of sturgeon will fully represent the wild population from which theyoriginated from, and survive well in the waters that they are being restored to.


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