Improving Mille Lacs Lake's walleye fishery as expediently as possible with as little negative impact to the local community as possible is the state's primary goal.
The situation will not turn around for several years. It will take time as well as careful management, monitoring and analysis for enough smaller walleyes to grow into the larger walleyes that anglers prefer to catch and that can contribute to future reproduction.
Even so, Mille Lacs remains a quality sport fishery. In addition to high numbers of large walleye, excellent quality fishing exists for northern pike, smallmouth bass and muskellunge.
Time and experience have proven that Mille Lacs is a resilient multi-species fishery for the anglers of Minnesota and tourists beyond our borders. A combination of regulations friendly to small walleye and cooperation among all users now will build and enhance the long-term sustainability of the fishery.
More walleye that hatched this spring were caught in nets during this fall's assessment, and many of those fish were six inches or slightly longer. The number of adult-sized fish was basically unchanged. It's too early to tell whether this fall's higher catch rates will have any long-term impact on the walleye population because the young fish will need to survive beyond the first year.
|DNR and Great Lakes Indian Fish & Wildlife Commission staff prepare a net during the fall population assessment.|
Survival rates improve for fish of this age at larger sizes. That larger size also makes them easier to catch in DNR assessment nets and be counted. But good walleye reproduction during the past several years has not translated into a stronger population of growing walleye, most likely because little walleye are being eaten. Effects from invasive species and climate change that are not well understood also may be impacting the fishery.
This fall's assessment did discover abundant forage. Nets recorded the largest perch hatch since the forage assessment was first conducted in 2006. Because predator fish appear to have another food source, more of this year's walleye hatch may survive into 2014 and beyond to grow into a stronger 2013 year class.
Yet even if more of this year's walleye hatch survives into 2014 and beyond, it takes several years for walleye to reach reproductive maturity and start replacing some of the larger old fish. For the fishery to recover, several years of good walleye reproduction and survival into proceeding years must occur and keep occurring on a consistent basis.
This growing segment of the walleye population also must be protected from significant fish harvest so more of these small fish can become large fish to supplement the spawning fish lost to mortality.
Fall 2013: Conducted the annual fall assessment using in- and off-shore nets, which revealed that the number of walleye hatched this year and still alive this fall is higher than last, creating the possibility that more younger fish may survive into the 2014 season.
|Fish captured during DNR netting on Mille Lacs Lake.|
Summer 2013: Contracted with nationally known walleye experts to conduct an independent review of our scientific data, population modeling and proposed management approaches.
Summer 2013: Continued to conduct our zebra mussel survey. The latest information indicates the population, which has been growing rapidly for many years, has declined from last year.
Spring 2013: Implemented a bio-energetics study (fish consumption estimates) to determine the relative effects of different fish species on forage and possibly small walleye survival.
Spring 2013: Implemented northern pike and muskellunge population estimate surveys.
Spring 2013: Implemented a walleye tagging study to better understand the number and size distribution of fish in the lake so that sound management actions can be taken.
Spring 2013: Implemented fishing regulations that allow anglers to keep more northern pike and smallmouth bass, which are predatory fish that prey on walleye and compete with walleye for the available forage.
Spring 2013: Implemented regulations designed to conserve small walleye.
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|A Mille Lacs Lake walleye netted by a DNR fisheries crew during assessment work.|
A serious problem has developed: not enough small walleye are becoming big walleye.
The answer is not clear but we are committed to making things better as fast as possible. Mille Lacs is in the midst of a small- to intermediate-sized walleye production problem. Despite good hatches of walleye, far fewer walleye are growing to catchable size and maturity than in the past. This is not yet a sustainability issue but it could be soon unless action is taken to improve the survival of young walleye.
We know the lake has an ample supply of large spawning-age fish that have been protected through harvest regulations. As a result, the lake has sufficient walleye egg, fry and fingerling production. This means Mille Lacs isn't like Red Lake where spawning stocks declined to the point where it needed to be stocked. It isn't like Leech Lake, either, where in the recent past, walleye abundance was likely impacted by cormorant predation. With plenty of egg production, the problem isn't hatching fry but farther along in the walleye life cycle.
Yes. It's part of the problem. What's happened is that since cooperative state and tribal management began, fisheries managers have successfully protected spawning female walleye by focusing the harvest walleye in the 14- to 18-inch size range. Currently, we are very concerned about conserving walleye less than 17 inches because they are the fish we need to grow to a larger size to sustain the population.
Yes. Restrictive smallmouth bass and northern pike regulations have likely increased the amount of predatory biomass in the lake. More predatory biomass translates into more predation on walleye and the forage species that walleye eat. Walleye cannibalism has also increased, and may contribute to recruitment issues when the forage base is low.
The impact of interactions among unwanted aquatic invasive species and other factors are not well understood but are making the lake increasingly biologically complex and unpredictable. For example, Eurasian watermilfoil has created more habitat for pike and bass. Zebra mussels are changing the nature of bottom substrates. Spiny water fleas may be competing with larval fish for small zooplankton. Climate and weather conditions - namely warmer weather patterns - have resulted in low tullibee numbers and higher hooking mortality due to warmer water temperatures. Water clarity increased in the mid 1990s and may be affecting plant growth and fish community composition.
The problem is complex. Many things are or have been going on at once. They include targeted harvest on smaller and younger walleye, more northern pike and smallmouth bass feeding on walleye or what walleye eat, more walleyes eating walleye, more unwanted aquatic invasive species, a smaller forage base, and less system predictability due to unknown interactions between fish community and new aquatic invasive species. No single action is the sole source of the problem. No single, one-time action will likely result in a solution.
The solution involves immediately controlling the walleye mortality factors we can because we can't control many complicating factors such as unfavorable weather for fry survival, catch-and-release survival and invasive species interactions. For the long-term health of the lake it is especially important to conserve the large 2008 walleye year class. These fish are in the best position to replace the lake's sizable but declining spawning population, especially considering that no strong year classes are coming up behind the 2008 year class.
There are things anglers can do that will help. All anglers should diligently follow whatever regulations and best practices are established. You also can help by minimizing the catch and release of large numbers of fish. When releasing fish, pre-wet your hands, cut the line on deeply hooked fish, return fish immediately and limit pressure during really warm periods of time. DNR also needs anglers to return walleye study tags and to encourage others to do so. This is important for understanding the size and scope of the fish population.
The DNR can't prohibit tribal netting because the federal courts have ruled that eight Chippewa Indian bands can regulate their own harvest of walleye free from state regulation so long as their actions do not compromise public health, public safety or conservation. The bands have voluntarily reduced their walleye harvest allocation from 142,500 pounds to 71,250 pounds for the 2013 fishing season. DNR will continue to strongly advocate for changes necessary for conservation of walleye and other fish populations.