Tuesday, April 12, 2011

Wolf River Walleye Spawn Update

Here is a report from Ron Bruch, the Upper Fox-Wolf Fisheries Work Unit Supervisor with the DNR.  I find this information interesting and helpful for tracking down those migrating Walleyes on the Wolf and Fox Rivers right now, I hope you do as well!

April 6 2011

It's starting to happen.........the walleye are starting to move on to the marshes on the Wolf and upper Fox Rivers for their annual spawning ritual. We worked last week on the upper Fox and were able to get 30 fish surgically implanted with 3 year sonic tags below the Eureka dam. The upper Fox is always about a week or more ahead of the Wolf and fish are probably spawning this week on the upper Fox.


We've moved to the Wolf this week and will spend all of our time on there from this point on. We started looking for fish on a few Wolf marshes in the New London and Shiocton areas on Monday this week with our electrofishing boats, and we set nets on a marsh in each area as well. The numbers of fish on the marsh is pretty low at this point although we expect that number to build exponentially over the next few days. So far after two days shocking (Monday & Tuesday) and 1 day lifting fyke nets (Tuesday) we have tagged about 600 fish (mostly from the nets so far) and have surgically implanted sonic tags in 36 fish (finished 20 in the Shiocton area, and have done 16 out of 20 in the New London area so far).

The temperature on the Wolf mainstem and in the marshes is up to 38.3 degrees F and the walleye need temps in the 40s to do their thing. The weather forecast is calling for highs around 50 or more for the rest of this week and in the 60s this coming weekend. This will definitely make things happen and we expect to see walleyes spawning in earnest by the weekend and early next week; with the fish pretty much wrapping up the majority of their spawning by the end of next week (unless the weather gets really cold next week which would extend things). In any event there should be fish coming off the marshes pretty well making their run back to the lakes by the end of next week - which will initiate the real fishing opportunities for anglers on the river.

Wolf River Cam

We will be tagging fish this year as usual from New London up to Shawano on the Wolf River. As most of you know we are doing some extra studies this spring comparing our catch rates between fyke nets and our shocker boats to see which is the most efficient gear for catching walleye for our spring tagging studies, and to see if there is any difference in the angler tag return rate of net vs. shocker caught fish over the next year. We will also be completing the initial surgical implants of 100 three year sonic telemetry tags into 50 adult male and 50 adult female walleye. As I mentioned above we are making good progress on this part of our planned work. We will be finishing putting tags in fish in the New London area today and will putting tags in 20 fish up near Shawano and 10 fish on Lake Winnebago (once the ice goes out on the lake and the fish start spawning there). Our walleye spawn not only on their traditional spawning marshes on the Wolf and upper Fox Rivers (on grass in old oxbows with flow going through them in spring), but they also spawn every year directly on gravel beds in the rivers and along the rocky shorelines of Lake Winnebago. I've even seen them spawning on sturgeon spawning sites in the Wolf River (such as Bamboo Bend) in years when the water flows were very low in spring and fish could not get into any marshes.

Speaking of spring flows - things look pretty good this year. There is nice flow going through most of the Wolf floodplain, marshes and bottom-land swamp maple stands along the Wolf. The fish will use all of these areas for spawning providing there is flow and grass or old leaf litter that they can lay their eggs on. The rain we got last weekend helped a lot and if the forecast is right it appears we should get enough rain over the next week or so to keep things going. Keep your fingers crossed. We are due for a good flow year. The last good spring flow year we had was 2008, which produced one of the largest year classes of walleye we have ever measured on the Winnebago System. As we expected, we are seeing a lot of males from this year class (making their first spawning run, at 13-15") in our sampling this spring. The females from this year class are not mature yet and won't show up in force for 2-3 more years. Regarding spring Wolf River flows and temperatures, you can track them on line at the USGS website http://waterdata.usgs.gov/wi/nwis/uv?dd_cd=01%2C02%2C14&format=gif&...

So - so far so good. We'll be putting in long days over the next couple of weeks to capture and tag the 10,000+ walleye we need to tag every spring to ensure we can stay on top of this great fishery. Long days - but days my crew and I look forward to every year.

Don't forget - if you capture one of our sonic tagged fish, please release it so we can continue to track it for the next three years (I've attached our sonic tagging study flyer again which shows how to identify these fish).

Also if you capture one of our regular floy tagged fish (one of the 10,000+ we will be tagging this spring with our normal yellow plastic dart tag inserted along the base of the back dorsal fin), please send the tag along with your name and address, the location and date of capture, and the tag, to the address on the tag (DNR, 625 E Cty Rd Y, Suite 700, Oshkosh, WI 54901).

Thanks - we greatly appreciate your cooperation and help with these tag returns. They are critical to our Winnebago walleye management program.

Till my next report..........


April 11 2011

The walleye are spawning in earnest on the upper Fox River, and just beginning to spawn on the Wolf River. We have been tagging fish captured via our shocking boats and fyke nets as planned this spring and as of the end of day yesterday (Sunday 4/10) are up to around 6700 fish total captured, tagged, and released (4700 shocking, and 2000 netting). Our goal is to tag at least 5000 with each gear and then compare the tag return rate over the next year of fish originally captured from the two gear types.

This year's spawning stock is, as we predicted, dominated by the males from the 2008 year class (the last year that we had good spring flows and lots of water in the river and spawning marshes). These males are the large number of fish between 13 and 16 inches anglers have been and will be seeing this spring. The females from this year class are not mature yet and we don't expect to see them making their first spawning run for a couple of more years. I've inserted a length frequency chart below that shows the size distribution of this year's walleye spawning stock on the Winnebago System.

The walleye will likely finish their 2011 spawning by the end of this week. Once these fish come of the marshes and out of the flooded woods where they are spawning, they should provide some excellent fishing opportunities. I would look for the best fishing beginning later this week and running for most of the rest of this month. Usually the best post-spawn walleye bite on the rivers is at the same time that the sturgeon are spawning. I expect to see the sturgeon start spawning within the next two weeks.

That's it for now - more later this week.

Ronald M. Bruch, PhD
Upper Fox-Wolf Fisheries Work Unit Supervisor
Wisconsin Department of Natural Resources
625 E County Rd Y, Suite 700
Oshkosh, WI 54901 USA
phone: (920) 424-3059

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