Lake information report

Name: Mille Lacs

Public Access Information

Fishing Regulations:

Lake Characteristics

Fish Sampled for the 2008 Survey Year

Length of Selected Species (Trapnet, Gillnet) Sampled for the 2008 Survey Year

Fish Stocking Activity

Fish Stocked by Species for the Last Ten Years

Fish Consumption Guidelines

These fish consumption guidelines help people make choices about which fish to eat and how often. Following the guidelines enables people to reduce their exposure to contaminants while still enjoying the many benefits from fish.

Pregnant Women, Women who may become pregnant and Children under age 15

General Population

DOWID - MN DNR, Divion of Waters' lake ID number.

Contaminants listed were measured at levels high enough to warrant a recommendation to limit consumption.

Listing of consumption guidelines do not imply the fish are legal to keep, MN DNR fishing regulations should be consulted.

Dioxin
Mercury
PCBS - Polychlorinated biphenyls
PFOS - Perfluorooctane sulfanate

Status of the Fishery (as of 09/01/2008)

Mille Lacs Lake is a 132,516-acre glacially-formed lake in east-central Minnesota. Fewer than 20 streams from a 240,000 acre watershed are tributary to the lake. The Rum River is the only outlet. Approximately 70 percent of the 85 miles of shoreline consists of suitable walleye spawning habitat exposed to wind and waves. Wind mixes water freely from top to bottom, resulting in little thermal stratification and good oxygen distribution at all depths. Offshore habitats include sand and mud flats, rock reefs, and a few small exposed islands. A few marsh areas exist in the southern part of the lake, and along some tributaries.

The Mille Lacs Lake gamefish community is primarily composed of walleye, yellow perch, northern pike, muskellunge, and smallmouth bass. Tullibee is an important forage species, and common minnow species include spottail shiner and mimic shiner. The recent invasion of zebra mussels is expected to create changes in Mille Lacs Lake. It will be important for anglers and other boaters to follow guidelines to prevent the spread of zebra mussels to other waters.

Walleye Walleye sampling in 2008 produced mixed indices of abundance. Gill net catch rates in the inshore nets were the second lowest recorded, with only 2007 catch rates being lower. The catch rate in 2007 appeared low based on unusual patterns in the geographic distribution of walleye in the nets, and also appeared to be low compared to the population estimate from the spring of 2008. Therefore, the 2008 catch rates may represent the lowest abundance of walleye recorded near shore. Walleye catch rates in the offshore nets were near average. The 2002 year class was poorly represented in the inshore gill nets, but was relatively abundant offshore.

The catch of walleye over 20 in has shown a decline in both inshore and offshore nets in recent years. The protected slots that have been implemented in recent years appear to have resulted in short-term increases in larger walleye by reducing the kill of older females. Catches of larger walleye have declined in both the inshore and offshore nets in recent years. The 2000 and 2001 year classes should be contributing to the population of walleye over 20 in, but those year classes are both very weak.

Indices of reproduction supported another year of above average recruitment. The CPE of YOY walleye in gill nets has been consistently higher since special regulations protecting larger fish have been in place. Higher indices of YOY walleye in recent years were also observed in the trawl and electrofishing samples. However, recent strong year classes appeared to have failed to persist when compared to long-term averages. The 2002 and 2003 year classes have both experienced relatively high fishing mortality, which could have driven abundance down. However, other year classes in the past also experienced high exploitation without showing the same degree of decline over time. Unrepresentatively low gill net catches observed in 2007, and perhaps 2008, would also explain some of the decline. Unidentified mechanisms associated with the increase in larger walleye may also play a part.

Northern Pike Northern pike sampled by the pike gill nets tended to be older but smaller than northern pike sampled in the standard inshore gill nets. The pike nets had a relatively high proportion of pike age 4 and older that were less than 28 in. One possible explanation would be that there were more males in the pike nets. However, sex ratios were about equal. Pike in the inshore gill nets were 57% male and pike in the pike nets were 53% male. Habitat may be a better explanation. The inshore gill nets are often set in areas with little or no vegetation, while pike nets are usually set in or immediately adjacent to vegetation. Larger pike are less dependent on vegetation for cover, and so may be expected more often in gill nets set in areas free of plant growth. The smaller sample size associated with the inshore nets may also have played a role.

There were more age 1 northern pike in the gill nets than in any previous year. Increased reproduction of northern pike may have been a result of increased egg production by protecting larger females with slot limits. Numbers and biomass of mature females in the inshore gill nets increased soon after protected slots were implemented in 1998, followed by increases in numbers of YOY and age 1 pike. The recruitment dynamics for northern pike appeared very similar to those observed in the walleye after the protected slots were enacted.

Yellow Perch Although the CPE of yellow perch in the gill nets increased from 2007, the CPE was about average for recent years. Numbers of perch over 9 in were average as well. A strong 2006 year class should begin to contribute more perch over 9 in next year. The 2002 year class, which was the strongest year class since 1996, is growing out of the fishery, and represented only 5% of the catch in the inshore gill nets.

Small yellow perch provided abundant forage in 2008, mostly as age 1. The 2008 year class was not expected to do well because of the late spring, cold summer, and suppression from the large 2007 year class. While catches of YOY perch in the trawl were below the median, they were higher than expected. Growth rate for small perch was predictably slow, given their abundance and the cool summer.

Tullibee Contrasting with the perch, tullibee were expected to benefit from the cool summer. The numbers of YOY tullibee in the trawl were the highest ever observed. Catches of YOY tullibee were 12 times higher than in 2007, and 36 times higher than the median since 1992. Also, the abundance of YOY tullibee in fine-mesh gill nets set throughout the summer were the highest observed in three years of forage netting. This apparently very strong year class should provide high quality forage for walleye and other large predators for several years.

Although catches of tullibee vary from year to year, they appear to vary differently in inshore and offshore areas. Inshore catches have been almost entirely age 1 tullibee since 2003. In several years, the inshore catch of age 1 tullibee exceeded the 1987-1997 median, but in subsequent years, those year classes were absent from the inshore gill nets. In the offshore gillnets, these same year classes demonstrated relatively good concordance from year to year. Variability in tullibee vulnerability to the different surveys may be influenced by environmental conditions that affect movement, geographic or vertical distribution, or possibly even mortality in different manners. Tullibee numbers have probably declined, but perhaps not to the extent represented by changes observed in the inshore gill nets.

Other Species A number of recent warm summers may be affecting the abundances of temperature sensitive species. Obvious declines in abundance have been observed for burbot and tullibee, while more subtle declines may be occurring for white sucker. On the other hand, species like smallmouth bass are showing a gradual increase in abundance as warmer temperatures lead to more favorable environments for warmwater species. Increases in the abundance of largemouth bass and other centrarchids are expected, but most of these species are not sampled well. Interestingly, rock bass, which might be expected to increase in abundance, seem to have peaked in the 1990s, and may now be in a period of decline. ?

For more information on this lake, contact: Area Fisheries Supervisor PO Box 138 1200 Minnesota Ave S Aitkin, MN 56431 Phone: (218) 927-7503 Internet: Aitkin Fisheries E-Mail: Aitkin.Fisheries@state.mn.us	Lake maps can be obtained from: Minnesota Bookstore 660 Olive Street St. Paul, MN 55155 (651) 297-3000 or (800) 657-3757 To order, use B0212 for the map-id.
For general DNR Information, contact: DNR Information Center 500 Lafayette Road St. Paul, MN 55155-4040 TDD: (651) 296-6157 or (888) MINNDNR Internet: www.dnr.state.mn.us E-Mail: info.dnr@state.mn.us	Turn in Poachers (TIP):     Toll-free: (800) 652-9093