The 2010 sturgeon spawning run has begun on the Wolf River. A handful of females have been spawning with their harems of males along the Wolf River Trail on County Highway X west of New London for a few days now, but the remaining 3000 or so females in the river that need to spawn yet have been waiting for the water temperatures to get a little higher. The wait appears to be over as a large number of fish moved into the Bamboo Bend spawning site on Highway 54 west of Shiocton last night and are vigorously spawning this morning. I suspected this to be the case when I heard the high flocks Canadian geese migrating north at 6:00 AM this morning. Every spring when we first see the high large V-flocks of Canadian geese heading north (not the low local flocks), we know we will be working spawning sturgeon that day. Given the weather forecast this week calling for high temperatures for most days (except tomorrow) in the 60s and possibly low 70s, we expect the majority of sturgeon in the Wolf River to spawn sometime this week.
Sturgeon spawn each spring at approximately 20 or more sites (out of about 60 known sites) on the Wolf, Little Wolf, and Embarrass Rivers. Once fish start spawning at a particular site, the activity lasts there about 3 or 4 days, with usually 2 days of peak activity at that site. Most of the nearly 60 different spawning sites on the Wolf River and tributaries are man-made, with only about 10 natural sites. The man-made sites are typically rip rapped areas on outside bends adjacent to deep water that people rocked to protect their river banks from erosion. Although erosion is a natural event on rivers, most of the erosion today is caused by boat wakes crashing into soft shorelines, which causes erosion rates to be much higher than normal. The best spawning site on the river is a natural site below Shawano Dam, which has always attracted large number spawning sturgeon, even before the dam was built in 1892. Thousands of fish spawn at this site every year. In many years we also will see a "second run" at several of the main sites, typically a small number of females that need higher a temperature to induce their ovulation, that spawn about a week or two after the main spawning event.
That's it for now........more later this week.
Ronald M. Bruch, PhD
Wisconsin Department of Natural Resources