Document Title:

Environmental Contaminants in Brook Trout (Salvelinus fontinalis) from Cove Brook and Two Tributaries of the Sheepscot River

Steven E. Mierzykowski Peter Ruksznis Daniel McCaw Jason Czapiga

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In July 2006, thirty-six brook trout (Salvelinus fontinalis) were collected from tributaries of two Maine rivers and used as surrogates for assessing potential contaminant exposure in Atlantic salmon parr. Eighteen trout were collected from two reaches in Cove Brook, a tributary of the Penobscot River, and 18 fish were collected from two tributaries of the Sheepscot River - Finn Brook and Weaver Brook. Brook trout were analyzed as whole-body samples (minus livers and a gill portion) for organochlorine compounds and trace elements. Brook trout in the study averaged 161 mm in length and 25 grams in weight. These average brook trout length and weight are similar to the size of Atlantic salmon parr. There was no significant difference in trout weights or lengths between the two DPS watersheds. Ages of trout in the collections ranged from I+ to III+. These brook trout ages would mimic the residence time of salmon parr in the two watersheds. Lipid content in brook trout averaged 3% with a range of 0.60 to 6.27 %. As with size and age, brook trout lipid content would be similar to Atlantic salmon parr. Except for low levels of p,p’-DDE detected in two of 36 fish - one from Cove Brook (0.004 µg/g wet weight) and one from Finn Brook (0.015 µg/g) - levels of 21 other organochlorine compounds, including Total PCB, were below analytical detection limits (< 0.002 µg/g to < 0.010 µg/g). Several trace elements were detected in whole-body brook trout samples. Mercury concentrations ranged from non-detect to 0.11 µg/g wet weight, well below the suggested tissue threshold-effect level of 0.20 µg/g. Similarly, arsenic, selenium, and zinc levels in brook trout were not elevated compared to concentrations reported in other trout studies or in other species used in Maine, regional, and national biomonitoring programs. Copper concentrations in brook trout were higher than levels reported in other species used in other biomonitoring programs. With the exception of copper, trace elements levels in brook trout generally appeared to be lower concentrations than white suckers collected in the same watersheds. Beryllium, molybdenum, and vanadium concentrations were below detection in all samples.

U.S. Fish and Wildlife Service



Maine Field Office Environmental Contaminants Program

Last updated: February 13, 2013