Jason Arndt, jarndt@shawanoleader.com
Leader Photo by Jason Arndt Fish biologists with the Department of Natural Resources take a lake sturgeon out of their net to tag near the Shawano dam Thursday.
Leader Photo by Jason Arndt Ryan Koenigs, right, chief sturgeon biologist of the Wisconsin Department of Natural Resources, measures a lake sturgeon Thursday while fish biologist Tom Penning tags it.
Wisconsin Department of Natural Resource fish biologists tagged about 400 sturgeon by the Shawano dam Thursday, up from 340 on Wednesday.
“More than likely, Thursday will reach its peak,” said Ryan Koenigs, the DNR’s chief sturgeon biologist. “They picked up overnight on Wednesday.”
The sturgeon did not start spawning in the Wolf River near Shawano until this week due to colder than usual weather. Koenigs, however, said the late start is not that unusual.
“It is a normal year compared to other years. They just didn’t get active until later,” Koenigs said.
Water temperatures rose to 52 degrees along the Wolf River on Thursday, up from 51 on Tuesday. Ideal water temperatures for sturgeon spawning generally range from 48 to 53 degrees.
Sturgeon Park in Shawano offers a rare opportunity for the fish biologists to gather information about the prehistoric fish because the dam area is spawning grounds for one of the strongest lake sturgeon populations in the United States. The fish spawn along the banks of the river, making it easier for the crews to net them, bring them in, tag them, determine their sex and harvest eggs.
“We are measuring and weighing along with counting them,” Koenigs said. “It allows us to determine how many fish are in the population to set harvest caps in the Lake Winnebago area.”
Biologists tagged the fish by applying a small plastic tag on each sturgeon’s dorsal fin and recording the number. The radio and sonic tags will help track the behavior of the fish after they’re released back in the Wolf — where they live, how far they travel, how long they live, etc.
Crews also used syringes to capture the sperm from the male fish and immediately placed the samples into a cooler. Buckets were used to collect the eggs from female sturgeon.
After collecting the eggs, workers disinfected them with an iodine compound to avoid transmitting diseases to nursery populations. A clay solution is used to make the eggs less sticky to better control fungus infections in the hatcheries.
The hatcheries will grow the sturgeon until they’re about 10 inches long and then release them.
Several groups were in Shawano this week to collect eggs.
U.S. Fish and Wildlife Services personnel gathered eggs for Georgia-based Warmwater Springs, which stocks sturgeon in Tennessee, Georgia and Alabama waters, and the Genoa National Fish Hatchery, which raises sturgeon to be distributed onto the Legend Lake complex on the Menominee Indian Reservation every other year, as well as other estuaries.
A group from the University of Wisconsin-Milwaukee collected some for the School of Freshwater Science. Eggs also will be used to foster sturgeon populations in the Menomonee and Milwaukee rivers in Milwaukee County.