Lake information report

Name: Rainy

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 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 09/02/2008)

The 2008 field season on Rainy Lake was characterized by abnormalities. A cold spring appears to have delayed growth for the lakes coolwater species by approximately two weeks. When combined with the high water experienced in the spring these same cold temperatures may have contributed to record catches of whitefish and tullibee in the annual shoreline seining assessment. Similarly record numbers of walleye were encountered in seine hauls and the angler creel survey, only to have gill net catch rates be dramatically lower than expected. The later of these findings may be related to a warm fall that might have affected typical walleye movements during that time of year, a view expressed by many anglers to the clerk conducting creel interviews.

Despite confounding environmental factors the 2008 large lake sampling program provided valuable insight to the status of the Rainy Lake fishery. Walleye, yellow perch, northern pike, smallmouth bass, and black crappie populations are healthy as indicated by various sampling methods. Gillnet sampling of walleye in 2008 indicates a need for close scrutiny over the next several years, but one year of low catch rates, particularly in a year where all catch rates were low, is not a reason for undue concern.

For the past 13 years walleye gill net CPUE has been at historically high levels. The 2008 CPUE of 4.83 per gill net was slightly down from the 6 per gill net captured in 2007. Walleye CPUE from 1983 to 1994 averaged 3.98 per net, since 1995 the average is 7.07 per net. Only twice (2001 and 2008) during the past ten years has the walleye CPUE been below six per net. Consistent recruitment has been the main factor contributing to the observed increase in CPUE.

Several factors may have contributed to the reduced numbers of walleye in the gill nets. A warm fall with water temperatures above normal for the time of year may have negatively affected the success of our fall netting. Anecdotal reports from anglers as well as conversations with the creel clerk operating at the same time indicate that walleye were not following their typical fall patterns in Rainy Lake for location or behavior. Additionally, poor production during 2002 and a near total failure of the 2004 year-class translates to poor numbers of 12-15 inch walleye in the gill net catch. Both age-4 and age-6 walleye were caught at very low rates for their respective ages. Their absence and the slight decline in CPUE is no reason for immediate alarm as it likely reflects natural variation in walleye production and annual variation in environmental factors.

Gill-net catch rates of larger walleye (over 17") have significantly increased in the past 30 years. In 2008 the CPUE of walleye over 17 inches dipped below one per net for the first time since the protected slot was put in place. Creel data from 2008, however, indicated that walleye 17 inches or greater in length made up 39% of the total catch for 2008 which had the highest walleye catch on record for Rainy Lake. Currently walleye greater than 17 inches (and less than 28 inches) are protected by length regulations.

Recruitment, expressed as year-class strength, is more consistent and higher than it was 15 years ago. Prior to the 1990s Rainy Lake walleye produced a strong year-class once every four years. Throughout the 1990s, six out of the ten year-classes were rated as strong. During the first half of the 2000s two of the six year-classes recruited to date are strong including the record breaking 2001 year class. Early indications are that two more strong year-classes are likely awaiting recruitment.

Seining and electrofishing data have been used to predict future walleye year-class strength on Rainy Lake. Prior to 1995 length data from summer seining provided the most reliable predictors. Since 1995 electrofishing indices have been more significant. This change may have arrived from changes in growth observed during the past 15 years. Seining data indicated the 2008 year-class will be weak, while the electrofishing data indicates it will be average. The unique weather associated with the initial growth of the 2008 year-class may make it difficult to predict which model will be more accurate. A cold, wet spring appears to have set growth back by ~2 weeks, though growth rates appear normal. A warm fall may mitigate the late start the YOY walleyes got in 2008 though only further sampling will tell.

Walleye fishing should remain exceptional on Rainy Lake. There are several strong year-classes within the protected slot that should provide good catch rates of large walleye and uphold reproduction. The 2003 year-class will continue to be the main contributor to the harvest, though the most recent creel indicated that early contributions from the 2005 and 2006 year-classes were already recruiting to the sport fishery. The 2006 and 2007 year-classes are showing good potential, and will likely begin to contribute heavily to the sport fishery over the next several years.

Northern pike gillnet CPUE returned to nearly normal levels after a sharp increase in 2007. Northern pike densities have great influence on northern pike growth; northern pike growth is negatively correlated with pike abundance (Pierce and Tomcko 2003, Pierce et al. 2003). Northern pike assessment shows there are several average year-classes present in the catch. The 2005 year-class has emerged as being strong. While large northern pike were present there was a downward trend in pike growth rates during the late 1990s into the early 2000s, this trend has changed and growth rates are increasing while recruitment is slowing. During the early 1990s mean northern pike length at age-3 was approximately 23 inches, during the late 1990s into the early 2000s length at age-3 dropped into the mid to upper teen range. In 2008 the mean northern pike length for age-3 was 21.73 inches, illustrating the faster growth rates.

Sauger abundance has steadily declined for the past 15 years. The CPUE observed in 2008 was the lowest ever. This trend may demonstrate density dependent and interspecies competition that influences the abundance and growth of walleye and sauger. Sauger fishing on Rainy Lake is a result of indirect catch, no angling parties contacted during 2008 were targeting sauger. Low sauger abundance, small average size, and a healthy walleye fishery likely are the cause for effort being directed towards walleye.

Lake whitefish are commercially fished on Rainy Lake and there is very little sport-fishing effort directed toward this species. Annual commercial harvest of lake whitefish has remained below the target quota every year since 1999. Fish Community Index Netting (FCIN) provides a standardized methodology for monitoring of this population. Based on four years of observation the lake whitefish population is showing no signs of overexploitation, however, monitoring should continue. Good recruitment in the past five years indicates the population is sustainable. FCIN is scheduled to be conducted again during the summers of 2011-12.

Spring sampling indicated the black crappie population is doing very well. Younger year-classes were present and mortality (natural and fishing) has greatly reduced the population of the strong year-classes from the mid-1990s. The recruitment of the 2003 year-class to the sport fishery has resulted in a very abundant fishery with exceptional opportunities to catch crappies. The 2008 creel reported the highest harvest of crappies ever recorded for Rainy Lake. The current status of the fishery indicates that crappie fishing should be exceptional during the next few years as the 2003 year-class contributes numbers of fish and the 2005 year class grows more fully into the acceptable size for harvest.

The 2008 smallmouth bass CPUE was down considerably from normal for Rainy Lake, but again was likely affected by the cold spring temperatures. Smallmouth bass populations have grown and have been protected only by the catch-and-release ethics common to most bass anglers. Bass growth on Rainy Lake is slow compared to area and state averages. However, there are plenty of memorable and trophy sized smallmouth bass present as demonstrated by the catch during the spring electrofishing and reports from anglers. Angler opportunities in 2009 should remain good.

Yellow perch gill-net numbers were above average for Rainy Lake. The length distribution of perch captured in the gill nets was predominantly in the less than nine-inch category. However, 28% of the perch sampled were more than nine inches in length and they should provide some decent harvest opportunities for the next few years. With the exception of 2004 recruitment has been exceptional for the past seven years, providing a strong forage base and developing angling opportunities.

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For more information on this lake, contact: Area Fisheries Supervisor 392 Hwy 11 E International Falls, MN 56649 Phone: (218) 286-5220 Internet: International Falls Fisheries E-Mail: InternationalFalls.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 B0394 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