Alaska’s salmon run
Anatomy of a Weir
Keeping a finger on the pulse If salmon are the life blood of Alaska and its rivers are the veins, then weirs are a health screening tool for river-specific populations
A weir is a temporary permeable fence across a river with an opening in the middle. This weir sits in Alaska’s Kenai National Wildlife Refuge on a Kenai River tributary. We’ve been using it as a platform to track the health of the Funny River early-run Chinook Salmon population since 2006.
Annual visits establish a baseline of personal health against which unhealthy trends can be detected before they become risk factors. We need baselines for the health of our salmon runs too. Weirs help us to establish those baselines and then detect changes in populations over time. They also help fisheries managers evaluate and adjust their management actions, reconstruct past salmon abundances, and forecast future salmon returns.
Basic anatomy of a typical video weir in Alaska.
Take a number. The “patients” wait briefly in the trap box on Alaska’s East Fork Andreafsky River before being seen and released upstream to continue their journey.
This Chum Salmon swam up the Yukon River and passed through our East Fork Andreafsky River weir on the way to its spawning grounds in Alaska’s Yukon Delta National Wildlife Refuge.
For well over a decade, fisheries biologists have been pioneering innovative underwater video technology at weirs; leading more accurate assessments of the health of salmon runs with less manpower.
Andrew and Jason from the village of Kwethluk help count salmon, take samples, and keep our remote Kwethluk River weir camp operational.
Chelsea, a crew leader, shows a scale she plucked from a Yukon River salmon at the Andreafsky weir.
Like the rings of a tree, scales are used to determine the age of fish.
Aaron, also a fisheries biologist with our Kenai Office, displays the escapement counts from the Kwethluk and Tulusak River weirs.
Case Study: monitoring Kuskokwim River salmon runs with weirs This noteworthy river—over 700 miles long—flows through the remote and wild landscape of southwest Alaska. It’s particularly significant in terms of supplying food for Alaska Natives: Alaska’s largest subsistence harvest of Chinook Salmon is taken from its waters each year.
The Kwethluk River flows through Alaska’s massive Yukon Delta National Wildlife Refuge.
Salmon are incredibly important both culturally and nutritionally to the people of Alaska and they want to know how the runs are doing.
Chris Tulik, a Refuge Information Technician who serves as a liaison between the Kuskokwim River communities and fisheries managers and scientists, presents in Yupik at the village of Kwethluk.
Due to their remoteness, some of our weirs are only accessible by boat or helicopter. In these cases, we have seasonal camps where fisheries technicians stay and keep things operational:
Killey River weir camp. Deep within the heart of Kenai National Wildlife Refuge, the Killey River is only accessible by helicopter.
East Fork Andreafsky River weir camp.
The tidal Chickaloon River weir camp includes a weather port for cooking,
a couple one-man tent platforms, outhouse, and gear shed.
Kwethluk River weir camp.
In Alaska we are shared stewards of world renowned natural resources and our nation’s last true wild places. Our hope is that each generation has the opportunity to live with, live from, discover and enjoy the wildness of this awe-inspiring land and the people who love and depend on it.
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