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Sturgeon Spawning Update from Ron Bruch on April 16, 2011

April 16, 2011

According to Ron Bruch, the sturgeon are now spawning at Bamboo Bend and a few other sites despite lower water temperatures. I’ll see what he has to say after today, but I am hoping to head out tomorrow to get a few photos and see them for myself–I will keep you posted! The following update has been posted with permission from Ron Bruch and the Wisconsin DNR:

“Wolf River Sturgeon Spawning Update – Saturday April 16

Just when you thought you could trust them……….you find out you can’t. Despite the cold weather and falling water temperatures on the Wolf River, a few female lake sturgeon along with their harems of males have moved into the shorelines at Bamboo Bend, Shiocton, and County X Sturgeon Trail, New London, and started spawning. The water temperatures in this part of the river nearly reached optimum for sturgeon spawning a few days ago, and apparently it was too much for a few early spawning females to bear and they began the ovulation cycle that they have been waiting four or more years for. It’s hard to say if this is the beginning of the big show or not, but I am heading up to the river in a few minutes with my crew to try to capture and tag some of these fish.

Each individual female lake sturgeon is on her own ovulation cycle spurred on primarily by water temperature, rate of water warming, and photo period. Some females spawn early, some late, most in the middle when the water temperatures are between 52 and 56 degrees F – this is Mother Nature’s way of not putting all of the lake sturgeon eggs in one time period basket, and the reason for the phenomena of “1st”, “2nd”, and “3rd runs” we see almost every year. The water temperatures in the Wolf River today are in the mid 40s – much less than optimum for lake sturgeon spawning, but as I mentioned, the early spawning females had enough time to “stew” in 50-52 degree water over the last week in the New London and Shiocton areas and they could not hold out any longer. So we’ll see what happens from this point on. We’ll have a better idea once we handle some fish today. Reports at this time is that all is still quiet at Shawano. You can log on to the Wolf River cam website to watch for sturgeon underwater below the Shawano dam at http://wolfrivercam.com/Shawano%20Dam.html, and from above the water at http://wolfrivercam.com/Shawano%20Above.html.

Generally lake sturgeon do not spawn every year. Winnebago lake sturgeon females don’t spawn for the first time until they are 20 to 34 years of age (48” to 60” long); and then only spawn every 3-5 years. Fifty percent of them are mature at age 27 when they are 55 inches long. Males don’t spawn for the first time until they are 14 to 31 years old (40” to 55” long); and then spawn every 1-3 years. I’ve attached a paper I and Fred Binkowski published several years ago on lake sturgeon spawning behavior – this will give you some additional insight into what the fish are up to this time of year.

Bruch & Binkowski, Lake Sturgeon Spawning Behavior

I’ll send you a report after we get off the river today.”

Ronald M. Bruch, PhD
Upper Fox-Wolf Fisheries Work Unit Supervisor, Wisconsin Department of Natural Resources

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