Fisheries & Ecological Services
Alaska Region   


Fairbanks Fish & Wildlife Field Office
Fisheries Monitoring Projects

Alaska Region YouTube

2015 USFWS Alaska fisheries technicians jobs

Data Series Reports for each project

Chandalar River Sonar Project
The Chandalar River is a large tributary of the upper Yukon River in interior Alaska and supports one of the largest runs of fall chum salmon in the Yukon River drainage. Between 1995 and 2006, we used sonar technology to estimate the abundance of fall chum salmon returning to spawn. In 2007, we began using a newer technology—Dual Frequency Identification Sonar (DIDSON)—to help gather the most accurate daily in-season counts and total fish passage estimates. This data helps managers make informed decisions and helps them better evaluate past decisions and actions. Information collected as part of this project is becoming increasingly important as stressors such as climate change, disease, selective harvest, and overall demand on the fisheries and resources in the Yukon River drainage continue to increase.


DIDSON sonar unit being placed in te Chandalar River.  Photo Credit:  USFWS Fish Technicians reviewing sonar data.  Photo Credit: USFWS Aerial photo of Chandalar River sonar camp.  Sonars are located just downstream on either bank.  Photo Credit: USFWS

Andreafsky River Weir Project
The Andreafsky River, a tributary of the Yukon River, supports one of the largest Chinook salmon and the second largest summer chum salmon returns in the Yukon River drainage. A resistance board weir installed on the East Fork of the Andreafsky River is used to collect abundance, run timing, and biological data from Chinook, summer chum, coho, and pink salmon. The Andreafsky River weir is one of the longest-running spawning escapement projects in the Yukon River drainage and is the only spawning escapement project in the lower river. This project allows managers to evaluate escapement goals; analyze trends in salmon abundance, size (length), age, and the male/female ratio; formulate run projections; determine harvest allocations; monitor long-term changes associated with climate change, harvest fluctuations, diseases, and other stressors; and better understand other fish species found in the area.

The camp associated with the weir is used for community outreach and education efforts. We are continually trying to improve our project on the East Fork, and encourage visitors; if you are in the area stop by and say “Hello”.


Sunset above Andreafsky camp.  The East Fork is designated as a Wild and Scenic River and certainly lives up to the title!  Photo Credit:  USFWS The Andreafsky weir is the largets resistance board weir in the Yukon Basin.  Here, migrating salmon are monitored.  Photo Credit: USFWS Fish Technician Jenn Volz sampling salmon at the Andreafsky weir.  Photo Credit: USFWS

Gisasa River Weir Project
The Gisasa River, located within the Koyukuk National Wildlife Refuge in north-central Interior Alaska, is a tributary of the Koyukuk River. A resistance board weir is used to collect information on abundance, run timing, and biology of returning adult Chinook and summer chum salmon in the Gisasa River. This project has produced 17 years of data enabling analyses of trends in population status, size, length, age, and gender composition of the run, developing future run projections, and setting and evaluating harvest and escapement goals and allocations. The information collected at the Gisasa River weir is vital to the difficult task of managing the complex mixed-stock subsistence and commercial salmon fisheries in the Yukon River. 

A floating weir helps us estimate escapement for Chinook and chum salmon on the Gisasa River.  Photo Credit:  USFWS A Fish Technician Collects Scales from a Gisasa River Chinook Salmon.  Photo Credit: USFWS Scales collected from salmon are used to estimate the age of fish returning to the Gisasa River to spawn.  Photo Credit: USFWS

Last updated: December 18, 2014