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.

Mille Lacs Lake Walleye Slot Limit Change:

• Walleye: Release immediately all walleye less than 18" or greater than 20.0", except one over 28.0" may be harvested. Possession limit is 2, with only one over 28.0".
• Northern Pike: Release immediately all from 33 .0" through 40.0". Possession limit is 3, only 1 over 40.0". No spearing.
• Smallmouth Bass: Release immediately all 17" through 20". Possession limit is 6, with only one over 20.0".
• Tullibee (Northern Cisco): Possession limit is 10.
• Other Species: Follow statewide regulations.
• Night Closure: No one may fish for any species or possess fishing gear on the lake from 10 p.m. through 6 a.m. starting at 10 p.m. on May 13, 2013, and ending at 12:01 a.m. on June 10, 2013.

Not necessarily. The state's walleye harvest has been below this year's allocation level of 178,500 pounds four of the last 10 years: 2003 (66,492 pounds), 2004 (79,412 pounds), 2008 (75,747 pounds) and 2009 (141,333 pounds) and in 2005 the harvest was below 200,000 pounds (195,271 pounds). Also, two-inch harvest limits are not unprecedented, and were implemented in 2001, 2002, and 2007.

That's difficult to predict but it may take three to five years before the walleye population is in a solid position again.

It is possible that a single year's netting such as last fall's assessment results could be wrong, but it is much less likely that the long-term trends observed in walleye abundance are not reflecting real changes. We will conduct a fish population estimate this spring to determine how accurately our models predicted the walleye population size. We will be tagging 20,000 walleye as part of a mark-and-recapture assessment as soon as the ice goes out. We will know more about the overall population starting by the end of June when we get tagging results back from our survey nets and anglers who have caught a tagged fish. We will also be conducting a new study to make estimates of prey consumption by predatory fish. We will keep you informed of our findings via DNR web pages. What we learn, you'll learn.

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 DNR has raised conservation concerns with the bands in the past year based on observed changes in population structure, some of which may have resulted from too many years of state and band harvest on too many smaller and younger walleye. 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.

The methods and timing of the take are not a conservation issue in and of themselves but negative impacts from such actions are. At Mille Lacs, Band netters and State anglers collectively have been taking too many males. Therefore, it is not a "when" or by "what method" problem. Instead, it's a "how much" and "which ones" problem. In this case, the conservation concern can be resolved by lowering allocations and spreading the harvest to include more length groups and more females. Also, the bands' spring netting accounts for only three percent of the female walleye biomass in the lake, and reproduction appears to have increased in recent years. Therefore, walleye production has not been reduced, even though other dynamics have changed.

The state closes the walleye fishing season during the spawning season on most waters (it is allowed certain portions of the Mississippi River) because walleye tend to concentrate in certain areas and are vulnerable to over-harvest. This strategy enables the state to offer a lengthy fishing season of nearly nine months. A lengthy fishing season provides optimal economic benefit for angling-related businesses such as bait shops and resorts. In theory, if each of the state's 5,400 fishing lakes and thousands of miles of river were monitored as intensively as Lake Mille Lacs, which is the most intensively monitored lake in the state, the DNR could allow the taking of a certain number of spawning walleye. However, this would result in more restrictive regulations for the rest of the year and likely a shorter fishing season. This is different than the long-held fish management strategy of affording anglers a longer fishing season with less restrictive regulations.