Fishing with Edna

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Back in the “olden days,” if you wanted to assess fish communities, you might set gill nets, fyke nets and traps and hope to capture all the species present in the environment. Personally, I am no fan of gill nets because they tend to kill or maim everything they catch. And, although I love the thrill of opening a well-set fyke net because you never know what might be inside, there’s a good chance you might miss rare or newly invasive species because their detection probability is so low. This year, as part of the Arctic Long Term Ecological Research (LTER) program, we are exploring the power of genetics to detect fish species by sampling the aquatic environment for fish DNA, a.k.a. environmental DNA (eDNA) or as Frances Iannucci and I like to call it, “Edna.”

Environmental DNA is a relatively new sampling technique that uses DNA from organisms, such as skin cells, urine, excrement and other sources, to determine species presence. This technique is incredibly sensitive because it only take a copy or two of mitochondrial DNA in a filtered water sample to detect a species. We are working in conjunction with the US Fish and Wildlife service to develop genetic primers for North Slope fish species in order to detect and monitor changes in fish community structure over time, simple by collecting filtered water samples from our lakes and streams. We also hope to use this technique to assess changes in species abundance using quantitative PCR techniques. With this goal in mind, Frances and I sampled Green Cabin Lake and the Kuparuk River prior to the Arctic grayling spawning migration. We predict the samples will show high concentration of Arctic grayling in the overwintering location, GCL, and no to low concentration of Arctic grayling in the spawning stream, the Kuparuk River prior to spawning. We predict that sampling later in the season, after the spawning migration, will show the opposite trend.  I’m thrilled to be part of this eDNA biodiversity assessment revolution and can’t wait to do more fishing with Edna.

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Due to the sensitivity of eDNA sampling, we needed a clean location, free of fish DNA, in which to prepare our sampling equipment. After a good washing with bleach, Toolik Field Station’s old stable isotope lab provides the perfect location in which to prep our sampling gear.

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Before fishing for fish DNA on the Kuparuk River, we first filter a control sample of deionized water to ensure good quality control for our samples.

 

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Ice covers most of Green Cabin Lake, but open water from the moat surrounding the lake provides enough water to test for fish presence and Arctic grayling abundance.

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A tiny phalarope paddles past, searching for food in a lake caught between winter and spring.

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