. Cottage country : an environmental manual for cottagers. Cottages; Vacation homes; Environmental protection; Pollution. What Fish species Are Selected? Within most lakes and rivers there are obviously many different species of fish. Given the limitations of man- power and analytical resources, it would be impractical and, in fact, un- necessar\' to sample all species. Mercury, for example,is a classic food chain pollutant. Such fish as wal- leye, pike, lake trout and bass eat other fish as a major part of their diet. As a result, they contain higlier mer- cury levels than such non-predator\'
. Cottage country : an environmental manual for cottagers. Cottages; Vacation homes; Environmental protection; Pollution. What Fish species Are Selected? Within most lakes and rivers there are obviously many different species of fish. Given the limitations of man- power and analytical resources, it would be impractical and, in fact, un- necessar\' to sample all species. Mercury, for example,is a classic food chain pollutant. Such fish as wal- leye, pike, lake trout and bass eat other fish as a major part of their diet. As a result, they contain higlier mer- cury levels than such non-predator\' fish as whitefish, sunfish and catfish. Therefore, when testing the fish from any given watercourse, predators are usually selected on the assumption that if their mercury content is low, then non-predatory species will also have low mercury levels. When testing for PCBs, mirex or DDT, a different selection process is followed. Tlie organic pollutants ha\c a higli affmity for fats. Tlierefore, fish with a higiT fat content such as salmon, smelt and perch are collected. Most fish are collected using net- ting techniques. In some cases, fish are selected from commercial fishermen's catch. Whenever possible, the collec- tion includes 15 to 20 fish of each species, representative of the size range from the lake being tested. For each fish collected, the length, wciglit and sex are recorded. In some cases, scale samples are kept so that the age of the fish can be determined. A boneless, skinless fillet of dorsal muscle is removed from the fish, pre- served and packaged for shipment to Environment Ontario laboratories for chemical analysis. Information about the individual fish, along with laboratory analysis re- sults, is used in developing the lake- by-hike, species-by-species, size-spe- cific contaminant classification tables. WhatAboutYour Lake? The lake selection process is influ- enced in some cases by the interest shown by anglers. If there are lakes you would like to see tes
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