I am sending out my sturgeon spawning report early today (and cancelling any thought of heading to Vegas). As good as we think we are in predicting what these fish are going to do and when they are going to spawn, the fish always win. The cold and abundant rain yesterday caused the water temperatures to drop a couple of degrees and the fish that were spawning finished over night and we found no new fish in to carry on the heavy 2012 spawning activity today. The crew mopped up about a dozen fish at Bamboo Bend this morning and are working fish at a couple of other private sites in the Shiocton area. The heaviest concentration of fish today seems to be below the Manawa dam on the Little Wolf River - this is a site where the public can also get a good look at the fish. Looking at the weather forecast and the behavior of the fish this spring, my next best guess as to when things will pick up again at the spawning sites that still need to come in from Shiocton to Shawano, is that fish won't come into these sites for a few days - perhaps Tuesday or Wednesday or later. It is entirely possible that Shawano could come in earlier or later than Wednesday - we'll keep an eye out and let you know.
The start, stop, and start again spawning behavior is typical of our lake sturgeon and probably other sturgeon species as well. Each female is on her own biological clock and will ovulate when she is finally ready, not before; and once she starts spawning she will keep spawning for the next 8-12 hours until she is finished. Water temperature is important, but the rate of warming is critical with the fish not only spawning at a wide range of temperatures (so they do not all lay their eggs at the same time), but not until they are ready to spawn (the females that is). Males are pretty much ready all the time once the females start showing up, and they will remain ready for weeks to take advantage of an ovulating female that arrives at a spawning site. Males also will not only spawn with many females over 4-5 weeks, but also will spawn at numerous sites - wherever they can find females that are ovulating or waiting to ovulate.
Once females finish spawning they will "rest" for a few hours perhaps at the spawning site before they move out - they are quite exhausted and ready to individually drift back downstream to the Winnebago lakes. The males don't head back until the full spawning season is in the books. As such the sex ratio, typically 6:1 males to females, is much more heavily tipped to males if there are "second" and "third" runs.