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The Aquatic eDNAtlas Project (U.S.)

• Open-access database containing crowd-sourced field surveys providing locations of aquatic species in the U.S.

iTrackDNA (Canada)

• A nation-wide initiative to provide resources for eDNA sampling; standardizing eDNA sampling methodology; integrating data into management and policy; and training/education

Chinook Salmon (Oncorhynchus tshawytscha)

Chinook salmon are the largest of all Pacific salmon and can be found in numerous Alaskan watersheds. As juveniles, they spend one year in the river before migrating to the ocean where they feed and grow. After 1-5 years, they return to the rivers they were born in to spawn and die.

Historically, they were highly sought-after by subsistence, personal use, sport, and commercial fishermen alike. Due to recent declines in abundance, however, harvest restrictions and closures have been implemented in many systems across Alaska.  Widespread burden is felt among Alaskan residents who rely heavily on this species for food, traditional uses, and an income.

Chum Salmon (Oncorhynchus keta)

Chum salmon are the most widely distributed and second largest of all Pacific salmon in Alaska. Unlike Chinook, most juvenile chum salmon migrate to the ocean shortly after emerging from the gravel where they hatched. After 3-4 years, chum return to spawn in the rivers they were born in and die, where their carcasses provide nutrients for their surrounding environment. 

Beginning in 2020, chum salmon began drastically declining throughout the Yukon River Basin. When paired with reduced Chinook abundance, many subsistence fishing communities are experiencing the dire consequences of dwindling resources that once supported them throughout the year.

Environmental DNA (eDNA)

Environmental DNA (eDNA) is DNA from a plant or animal that the animal shed through sloughing of cells, slime, etc... The amount of time that eDNA remains intact in a flowing river depends on the river's hydrology and environmental factors like water temperature, soil type, and turbidity.

DNA Extraction

When researchers filter river water samples for salmon DNA, the paper filters they use collect everything in the water at that location. While this includes DNA, things like sediment and organic matter also get retained by filters. To analyze these samples in the lab, researchers must first isolate DNA from these other particles using a series of steps called "DNA extraction". The resulting product is a single tube of suspended DNA!

Quantitative polymerase chain reaction (qPCR)

qPCR is a laboratory technique that researchers use to determine the relative amount of DNA for a specific species (e.g. Chinook salmon) found in a sample of extracted DNA. For this study, researchers are using qPCR to determine the relative amount of Chinook and chum salmon DNA found in samples collected daily. They will then use these concentrations to determine whether they can predict daily salmon passage, which will be validated by comparing these predictions to known salmon counts at each site.

Subsistence fishing

Subsistence fishing involves the harvest of fish for noncommercial, customary and traditional uses. Many Alaskans throughout the Yukon River Bain (and elsewhere) rely heavily on the ability to annually harvest species like Pacific salmon for food throughout the year. When fisheries managers must restrict harvest of a particular species due to low numbers, subsistence fishing opportunities are prioritized (AS 16.05.258). More information can be found here.