John Kubisiak, DNR Fish Biologist
December 21, 2015
There are a number of reasons why fish don't bite. The two most likely causes include either a low fish population, or abundant natural forage competing with anglers' bait. For George Lake walleye, we can rule out a low population, because Great Lakes Indian Fish & Wildlife Commission (GLIFWC) estimated the adult walleye population this spring at 3.4 per acre. The common cause of not catching fish even though good numbers are present is that they have keyed in on abundant natural food and are choosing not to bite what anglers are offering.
George has a history of consistent strong walleye recruitment, but I'm paying close attention to recruitment after two consecutive weak walleye yearclasses. We had similar results on other Oneida County lakes: solid walleye lakes that had less than 5 young-of-year per mile in 2014 and 2015. Walleye normally experience big swings in recruitment, and we can sustain an adult population with one decent yearclass every 3 or 4 years. If a fall survey shows another weak yearclass on George in 2016, then I plan to stock fish in 2017.
You ask whether muskies might be impacting the walleye population.. Two technical papers come to mind on this topic*. A Minnesota study looked for changes to fish communities due to muskie stocking, but did not find any widespread effect. A diet study by UW Stevens Point researchers found that muskies in northern Wisconsin eat mostly yellow perch and white suckers and consume very few walleye. I don't believe muskies differentiate between perch and walleye, but the fact that perch are active and walleye inactive during daylight hours is likely important.
I consider muskie populations above about 0.5 per acre to be moderately high density; we start to see declines in growth when we exceed 1 per acre. We did not estimate the muskie population on George during our 2010 survey, but our catch of 99 muskies is fairly high for that species.
I changed the George Lake muskie quota from our standard stocking rate of 0.5 per acre to 0.25 per acre in even-numbered years. I've been using the lower rate on a few large waters that I manage for lower muskie densities and better growth potential. The actual number of fish stocked changes from 217 to 111, not quite in half because the official lake acreage is currently 443 (we used 435 in Wisconsin Lakes).
Every second year, we were stocking about 2 per acre from mid-1960s through the 80s; 1 per acre in the 1990s; 0.5 per acre 2002 - 2014 and now 0.25 per acre. Muskie anglers were releasing most fish by early 1990s and I think our current hatchery product is really good, but it is amazing that we can keep cutting stocking in half and produce a fishery.
*Knapp et al 2012. Fish community response to the introduction of muskellunge into Minnesota lakes. http://afs.tandfonline.com/doi/abs/10.1080/02755947.2012.663684
Bozek et al 1997. Diets of muskellunge in northern Wisconsin lakes.