Chinook Salmon Research Initiative
Nushagak River Chinook Salmon

Nushagak River Adult Chinook Salmon Spawning Abundance

Adult Chinook salmon mark-recapture and age, sex, and length studies. Chinook salmon spawning escapement indices have averaged about 157,000 over the years. Spawning escapement counts on the Nushagak River began in the late 1960s and were initially conducted using aerial surveys. Sonar replaced aerial surveys as the primary method of monitoring escapement on the Nushagak River in the mid-1980s. While the sonar can count individual fish, there are multiple species of salmon on the Nushagak River which makes counting individual Chinook salmon problematic. In addition, the sonar only counts a fraction of the overall river width and therefore is at best an index of abundance in any given year. Most believe the Chinook salmon run in the Nushagak River to be one of the largest wild runs in the world. In 2011, an acoustic tagging study was implemented to track Chinook salmon migration past the sonar site. This study estimated the proportion of upriver migrating Chinook that traveled outside the range of the sonar and expansion of the sonar count, accordingly. In addition to the acoustic tagging study, a simultaneous mark-recapture experiment to estimate the inriver abundance of Chinook salmon will take place. This will provide an inriver abundance estimate that can be compared with the sonar/acoustic tag estimate and full drainage wide estimates of escapement. Also, two weirs will be installed on spawning tributaries and fish will be sampled at these weirs, and in the lower river, for tissues, age, sex, length, and tag information.

Nushagak River near Dillingham, Ekwok

$1,970,000

2014, 2015, 2016

Adult abundance

Adult

Nushagak River Chinook salmon