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SOMBA K'E/YELLOWKNIFE
Something in Baker Creek is making certain diminutive species of fish inhabiting Baker Creek a little less diminutive.

Female and juvenile slimy sculpin grow larger in contaminated Baker Creek and researchers don't know why. - photo courtesy of Wikimedia

After three rounds of testing researchers are still unsure as to what is causing the increase in size, according to reports from the Giant Mine Remediation Project Team.

"There are some effects that we noted but we cannot attribute them to the mine effluent … At this time we still can't tell," said Adrian Paradis, acting manager of the Giant Mine remediation project.

Tests conducted to determine any effects related to Giant Mine, one of the most contaminated sites in Canada, show that female and juvenile slimy sculpin and young ninespine stickleback found in Baker Creek, are slightly larger than those found in the Yellowknife River. Both species average less than seven centimeters in length as adults.

The fish were collected from a widening of stream called Baker Pond, near the junction between the Ingraham Trail and Vee Lake Road.

"Preliminary data suggests this could be due to various factors such as the treated mine effluent, contamination in the sediment, or the shallowness of Baker Creek," Paradis later wrote in an e-mail, adding more tests still need to be done.

The team began testing in the area in 2004 as part of the government's Environmental Effects Monitoring Program as required by the Metal Mining Effluent Regulations. Other rounds of research were conducted in 2006, 2010 and most recently in July. The results of the latest test are expected to be released next year while another phase of testing will be conducted in 2015.

Researchers have been looking at the fishes' gonads, liver and flesh as well as measuring their length and weight. Tests have also been done on other aquatic life and water from the creek. All results were compared with a reference area upstream from the mine.

Research on the water in the Baker Creek exposure area revealed high concentrations of arsenic, copper, selenium and nitrate when compared with the Canadian Water Quality Guidelines. Depending on the year, concentrations of arsenic were between 35 and 23 times what is set out by the guidelines.

High arsenic levels in Baker Creek have been a concern over the years. Last year during the spring melt, the creek broke its banks and flowed into a tailings pond, before flowing back into the creek and into Back Bay. As a result, tests showed arsenic levels 700 times higher than the acceptable levels for drinking water. Risk of other incidents like this continue to be a concern.

Meanwhile, tests showed effects on water fleas, algae and fathead minnows – another small fish of around five centimeters in length -- exposed to undiluted concentrations of mine effluent for seven days. Water fleas displayed decreased survival and reproduction during the test while the growth rate of algae was inhibited, as were the survival of the fathead minnows.

Still, Paradis said the toxic responses found in the aquatic life are nothing to panic about.

"The results are not overly concerning as additional toxicity results on other test species show no effect related to treated mine effluent," he wrote. "The toxicity effects related to mine effluent have been classified as mild."

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