Lake information report

Name: Winnibigoshish

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 06/23/2008)

The lake Winnibigoshish assessment is completed annually to track changes in abundance and growth of all game species. The assessment season starts with gill netting in late June. Gill netting is conducted through July to sample game and non-game species age 1 and older. Abundance, growth rates, presence of parasites etc. is determined from this data. Seining is conducted during the month of July. The goal of seining is to sample young game and non-game species (including minnows) and to track growth of age 0 walleye and perch. Trawling is conducted in August to continue tracking growth rates of age-0 walleye and perch. Trawling gives us the first clue to abundance of age-0 walleye and perch for that year. Temperature and dissolved oxygen profiles are taken from June through August and water chemistry analysis is done in August to track changes in the system that may affect the ability of some species to prosper or exist in the lake.

Walleye Gill nets Walleye were sampled at a rate of 5.0 per net, which was average for Lake Winnibigoshish. Walleye sampled varied from 7.1 to 25.2 inches with a mean length of 15.2 inches and mean weight of 1.4 pounds. The walleye population appeared to be healthy with most age classes sampled between age 1 and 12. Year-class strength was computed for walleye between age 2 and 7. Three average year classes (2003, 2004 and 2005), and three strong year classes (2001, 2002, and 2006) were sampled. However, none of the strong year classes were exceptionally strong. Mean back-calculated growth was similar to the Lake Winnibigoshish and statewide average for all ages, attaining 17.9 inches after five growing seasons.

Seine and trawl Slow spring warming and below average summer temperatures appear to have resulted in some of the slowest growth observed since 1983. The shortened growing season resulted in smaller than average age-0 walleye. Slow growth and small size of fingerling walleye usually results in a weak year class.

Relatively few age-0 walleye were sampled by seine in 2008. Seine catch rates have not correlated to ultimate year-class strength for walleye in Lake Winnibigoshish. Growth rate of age-0 walleye has been a better predictor of year-class strength. Mean lengths of age-0 walleye varied from 2.5 inches to 3.2 inches from July 18 to July 31.

Mean trawl catch rates for age-0 walleye were average when compared to catch rates observed since 1972. Age-0 walleye growth recorded through the first week of August was slower than mean growth in all but three years since 1983, reaching a mean length of 3.8 inches on August 8. Slow growth of age 0 walleye nearly always results in a weak year class.

Yellow perch Gill nets Yellow perch (perch) are an important species for anglers and as a prey item for walleye and northern pike. The catch of perch in assessment nets reached an all-time low in 2005 largely because of poor year classes in 2000 and 2002. A strong year class was produced in 2003. As this year class has matured, the catch of perch has increased.

Perch were captured at a rate of 68.4 per net in 2008. This catch rate was slightly lower than average for lake Winnibigoshish. Perch sampled in 2008 varied from 4.8 to 11.2 inches with a mean length of 7.3 inches and mean weight of 0.19 pounds. Age classes 2 through 8 were sampled by gill net. An index of year-class strength was computed for ages 3 through 7. The 2001 and 2004 year classes were average, the 2002 year class was weak, and the 2003 and 2005 year classes were strong. As the 2003 and 2005 year classes continue to mature, abundance and size structure should continue to improve. The catch was biased towards younger perch with 69% of the catch made up of age 2 through age 4 fish. Yellow perch growth was relatively slow through age 2, then increased to average from age 3 to age 10. Perch grew to a mean length of 9.3 inches at age 6.

Relative health of the yellow perch population has been described by the percent of perch longer than 9 inches in the gill net catch. As perch catch rates decreased during the mid 1990's, the proportion of large perch (longer than 9 inches) increased. The proportion of large perch peaked as gill net catch rates fell below the first quartile. In 2005, the proportion of large perch sampled in gill nets declined for the first time since 1998. The proportion of perch longer than nine inches was stable in 2005 and 2006 at 16.9 percent, then declined to 9.8% as young perch were recruited to the fishery in 2007. Although many small fish remain in the population, the strong 2003 year class has grown large enough to affect the proportion of perch longer than 9 inches. The proportion of perch longer than 9 inches increased to 12.7 percent in 2008.

The microsporidian parasite heterosporis has been documented in Lake Winnibigoshish yellow perch. No evidence of heterosporis was observed 2008.

Seine and trawl Catch rates of age-0 yellow perch were near average for both seine and trawl. No correlation is evident between catch rates of age-0 yellow perch and ultimate year-class strength.

Northern pike

Gill net catch rates of northern pike (pike) increased from 1999 through 2005 and exceeded the third quartile in four of six years from 2002 through 2007. Northern pike catch rates declined to 8.2 per gill net in 2008. Pike sampled varied from 14.8 to 29.7 inches with a mean length of 21.4 inches. All age classes between age 1 and 6, and age 8 were sampled by gill net. Age two, three, and four pike were most abundant, and pike exhibited growth rates that were similar to state wide averages through all ages.

No pike longer than 30 inches were sampled in this assessment. This does not mean that they are not present in the system, but it is an indication that their abundance has decreased. The decrease in size structure can be attributed to several causes. Cisco abundance has declined (cisco are preferred prey that provides more energy than other similar size prey), this may lead to slower growth rates. Conditions for reproduction and survival have been good. This may lead to increased density and more competition for food, which also causes decreased growth rates. Angler harvest can have a large impact on the size structure of a pike population. When anglers harvest the largest fish they catch, they can cause a slow decrease in the size structure of the fish they are harvesting. This occurs because fish are removed faster than they can be replaced. Considering the current size structure anglers should release all pike longer than 25 inches. This should result in pike growing closer to their potential and increase the chance to catch 8 to 10 pound fish.

Cisco Gill net catch rates decreased to the third lowest level observed since 1983. The catch rate of 10.5 per net was well below the first quartile. The cisco population has been lower than average for 8 of the last 10 years. This is likely due to increasing water temperatures affecting reproduction and survival. Cisco sampled in 2008 varied from 5.4 to 15.4 inches with a mean length of 8.2 inches.

Water Quality Water samples were taken on August 5, 2008. Physical and chemical parameters measured were within the range observed since 1983. Six temperature and dissolved oxygen profiles were taken between June 23 and August 8, 2008. Dissolved oxygen stratification was evident from July 21, through August 5. No evidence of thermal stratification was found in 2008. Thermal and dissolved oxygen stratification may result during periods of high air temperatures and low wind. When wind speeds increase to moderate levels (15 mph) the entire water column appears to mix.

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For more information on this lake, contact: Area Fisheries Supervisor 1201 East Hwy 2 Grand Rapids, MN 55744 Phone: (218) 327-4430 Internet: Grand Rapids Fisheries E-Mail: GrandRapids.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 B0010 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