2013 DNR Lake Sarah Fish Survey Summary Below are preliminary summaries of last Fall's fish sampling not yet posted on LakeFinder. Different gear target fish species and sizes quite differently; for example, northern pike and walleye are better caught by gill nets, while bluegill are better caught with trap nets. Values of black crappie might be from either net type. Our net-based surveys under-sample largemouth bass; electrofishing better evaluates bass abundances and size structures, but requires extra sampling with different equipment. The full summary of all lakes sampled can be found at http://www.dnr.state.mn.us/areas/fisheries/westmetro/lakesurvey.html
2013 Preliminary Fish Survey Summaries
Lake (County) Date Fish Species No. per net Average Length (in) Max. Length (in)
Sarah (Hennepin) Northern Pike 13 24.1 36.1 7/15-17; 9/23-25/13 Walleye 1 17.9 22.8 also White Crappie Black Crappie 14 7.3 11.1 --10-in avg size Bluegill 24 6.3 8.5
DNR sample using electrofishing - running electricity through the water with a specialized boat, typically at night-- from late spring to early fall for two types of studies: 1) largemouth bass are best sampled using this method, as they are under-sampled in lake survey nets. 2) in autumn, we check some walleye-stocked waters to measure success of fish stocked earlier in the year. In electrofishing, fish are temporarily stunned and brought into the boat for counting and measuring, then returned live.
Lake (County) Date Species Number per hour Average length (in) Max length (in)
Sarah (Hennepin) Lg Mouth Bass 43 11.1 16.9 9/25/13
2007 MN DNR Lake Survey / Fish Assessment Results
Note: These preliminary values are from summertime netting assessments using gill nets and trap nets. The different net types catch various fish species/types differently because of differences in construction and where the nets can be located; for example, gill nets catch walleye, northern pike, and yellow perch better than trap nets, and trap nets tend to catch bluegill better. Representative numbers of crappie species might be caught from either or both net types. Largemouth bass are not caught in nets in proportion to their presence, and thus this survey type typically underestimates bass abundance.
Lake (County) Species Number/Net Average length Max Length Date (inches) (inches)
Sarah (Hennepin) Northern Pike 7.1 28.1 38.7 July 16, 2007 Largemouth Bass 1.0 11.9 19.1
No PFOS found in lake Sarah fish netted in last summers survey. The Minnesota Pollution Control Agency (MPCA) collected 381 fish from 20 area lakes and 2 rivers last spring and summer. The fish sampling was part of MPCA’s response to finding elevated levels of perfluorochemicals in fish from Lake Calhoun in Minneapolis in 2007. About 30 lakes in the metro area were selected for sampling to see if the Calhoun findings were unusual or whether other metro lakes also could be affected. Fish collected were analyzed for 13 different PFC compounds, those tested from Sarah included 7 bluegills, 5 crappies, and 5 Northern Pike. Of the 13 PFC compounds, only PFOS (perfluorooctane sulfonate) has been found to accumulate in fish tissue. 3M manufactured the chemical for decades for use in Scotchgard, firefighting foams and other products before ceasing production in 2002. MPCA reports (Star Tribune 1/30/08) that Sarah was among the metro lakes that showed little or no trace of PFOS. The entire report can be viewed by this link. Fish Consumption Advisories. Several residents have asked about the consumption recommendations for our lake too. Our lakes specific advisories are shown in the window below. The Minnesota Department of Natural Resources (DNR), the Minnesota Pollution Control Agency (MPCA), and the Minnesota Department of Health collaborate in producing the fish consumption advisory. Each year, the DNR collects fish from lakes and rivers for testing. Minnesota has 6,000 fishable lakes. Fish from nearly 1,000 lakes and streams in Minnesota have been tested for contaminants. All waters from which fish have been tested are listed in the tables that can be found by this link to the MN Dept. of Health website. The waters that have been tested are not necessarily more contaminated than those not tested. These guidelines are based on the contaminant level measured in fillets.
Revised fish consumption advice features simpler format, encourages people to eat more fish
The Minnesota Department of Health (MDH) has revised its fish consumption advisory to include a large new body of data on contaminants in fish from Minnesota lakes and rivers. The advisory is also in a new format designed to make it easier to understand while encouraging people to eat more fish. For more than 20 years, the fish consumption advisory has helped Minnesotans choose which species of fish to eat and how often in order to minimize their risks from contaminants in fish while gaining the many health benefits from eating fish. For this advisory, MDH staff analyzed and interpreted laboratory results from approximately 4,500 samples of fish tissue, more than twice the usual amount. The data came from field collections in 2006 and 2007 by DNR and the subsequent analysis of PCBs and mercury in fish tissue by MDA. The increased collections and analysis were made possible in part by funding from the Clean Water Legacy Act of 2006. To make information for specific lakes and rivers easier to understand, two major changes were implemented. Symbols are no longer used to represent the meal advice and meal advice categories are now listed at the top of the advice table. While for some species of fish, contamination concentration increases with size, for many species the concentration does not change significantly with size. Therefore, more of the meal advice is now for “all sizes” of a particular species of fish, rather than categorized by length of fish. The advisory is also aimed at encouraging people to eat more fish. Previous guides advised consumers that they could eat fish that had a once-per-week recommendation OR a meal of fish from the once-per-month category, but not both. Now, MDH is advising consumers that they may eat fish from the once-per-week category AND the once-per-month category. “The health benefits of eating more fish are clear,” McCann said. “Additional data and a thorough analysis show that this slight change will still be safe for people eating fish.” The contaminants noted in the site-specific advisory are those that have been measured in levels high enough to warrant a recommendation to limit consumption. More information on contaminants in fish may be found at www.health.state.mn.us/divs/eh/fish/faq.html. For more on the Minnesota Fish Consumption Advisory, visit www.health.state.mn.us/divs/eh/fish/index.html.
2003 Fish Creel Survey During Winter Season 2002-03 and the Open water Season 2003 The Minnesota DNR Division of Fisheries performed a Fish Creel survey of 3 Hennepin County Lakes (Sarah, Independence, and Medicine lakes). The report, in 2 part Adobe Acrobat (.pdf format), can be viewed by use of the links below.