An ongoing coded-wire tag project, used as part of a stock assessment program for Chilkat River Chinook salmon Oncorhynchus tshawytscha and coho salmon Oncorhynchus kisutch, will be conducted during fall 2020 and spring 2021 to provide estimates of smolt abundance and marine harvest for Chinook and coho salmon. This project uses modified Peterson 2-event mark-recapture methods to estimate smolt abundance, and port and creel sampling of coded-wire tags in mixed stock commercial and sport fisheries to estimate marine harvest for both species. Juvenile salmon will be measured for length and weight, marked with adipose fin clips, and tagged with coded wire tags in fall 2020 (juvenile Chinook salmon) and spring 2021 (Chinook and coho salmon smolt) as event 1 of the mark-recapture study. During event 2, adult Chinook salmon will be sampled for missing adipose fins, coded wire tags, age, sex, and length in Chilkat River fishwheels and drift gillnets, which are operated in the lower Chilkat River as part of a separate adult mark-recapture project. Adult Chinook salmon will be also sampled for missing adipose fins, coded wire tags, and age, sex, and length during Chilkat River drainage spawning grounds surveys to complete event 2 sampling. Coho salmon will also be sampled as adults during event 2 in the lower Chilkat River fishwheels. Age composition of Chinook salmon adults will be estimated by scale ageing techniques; age composition of coho salmon smolt and adults will also be estimated. The Alaska Department of Fish and Game uses these data to make local and regional management decisions. Chilkat Chinook salmon is a Pacific Salmon Commission exploitation rate and escapement indicator stock and has recently been added to the base model of abundance indicator stocks for the Chinook Technical Committee, which influences coastwide management.

An ongoing coded-wire tag project, used as part of a stock assessment program for Chilkat River Chinook salmon Oncorhynchus tshawytscha and coho salmon Oncorhynchus kisutch, will be conducted during fall 2020 and spring 2021 to provide estimates of smolt abundance and marine harvest for Chinook and coho salmon. This project uses modified Peterson 2-event mark-recapture methods to estimate smolt abundance, and port and creel sampling of coded-wire tags in mixed stock commercial and sport fisheries to estimate marine harvest for both species. Juvenile salmon will be measured for length and weight, marked with adipose fin clips, and tagged with coded wire tags in fall 2020 (juvenile Chinook salmon) and spring 2021 (Chinook and coho salmon smolt) as event 1 of the mark-recapture study. During event 2, adult Chinook salmon will be sampled for missing adipose fins, coded wire tags, age, sex, and length in Chilkat River fishwheels and drift gillnets, which are operated in the lower Chilkat River as part of a separate adult mark-recapture project. Adult Chinook salmon will be also sampled for missing adipose fins, coded wire tags, and age, sex, and length during Chilkat River drainage spawning grounds surveys to complete event 2 sampling. Coho salmon will also be sampled as adults during event 2 in the lower Chilkat River fishwheels. Age composition of Chinook salmon adults will be estimated by scale ageing techniques; age composition of coho salmon smolt and adults will also be estimated. The Alaska Department of Fish and Game uses these data to make local and regional management decisions. Chilkat Chinook salmon is a Pacific Salmon Commission exploitation rate and escapement indicator stock and has recently been added to the base model of abundance indicator stocks for the Chinook Technical Committee, which influences coastwide management.

An ongoing coded wire tag project, used as part of a stock assessment program for Chilkat River Chinook salmon Oncorhynchus tshawytscha and coho salmon O. kisutch, will be conducted during fall 2022 and spring 2023 to provide estimates of smolt abundance and marine harvest for Chinook and coho salmon. This project uses modified Peterson 2-event mark–recapture methods to estimate smolt abundance, and port sampling of coded wire tags in mixed stock commercial and sport fisheries to estimate marine harvest for both species. Juvenile salmon will be measured for length and weight, marked with adipose fin clips, and tagged with coded wire tags in fall 2022 (juvenile Chinook salmon) and spring 2023 (Chinook and coho salmon smolt) as event 1 of the mark–recapture study. During event 2, adult Chinook salmon will be sampled for missing adipose fins, coded wire tags, age, sex, and length in Chilkat River fishwheels and drift gillnets, which are operated in the lower Chilkat River as part of a separate adult mark–recapture project. Adult Chinook salmon will be also sampled for missing adipose fins, coded wire tags, and age, sex, and length during Chilkat River drainage spawning grounds surveys to complete event 2 sampling. Coho salmon will also be sampled as adults during event 2 in the lower Chilkat River fishwheels. Age composition of Chinook salmon adults will be estimated by scale ageing techniques; age composition of coho salmon smolt and adults will also be estimated. The Alaska Department of Fish and Game uses these data to make local and regional management decisions. Chilkat River Chinook salmon is a Pacific Salmon Commission exploitation rate and escapement indicator stock and has recently been added to the base model of abundance indicator stocks for the Chinook Technical Committee, which influences coastwide management.

This plan describes the coded-wire tagging of juvenile Chinook salmon Oncorhynchus tshawytscha on the Unuk River for the 2019 and 2020 brood years, which covers the coded-wire tagging of parr in fall of 2020 and 2021 and smolt in spring of 2021 and 2022, and sampling returning adults for age, sex, length, and coded-wire tags in escapement from the 2022 through 2027 return years. This study provides estimates of smolt and parr abundance, overwinter (freshwater) survival, mean lengths of juveniles, and harvest information of Chinook salmon originating from the Unuk River in Southeast Alaska. A separate project will be conducted on the Unuk River that employs aerial and foot survey peak counts to estimate large (≥660 mm mid eye to fork of tail length) adult Chinook salmon returning to the river in 2020 and 2021. The primary goals of this and the companion study are to estimate inriver run size, total run size, marine harvest-exploitation rate and harvest distribution, smolt and parr abundance, marine survival (smolt to adult) and overwinter survival (parr to smolt). The Alaska Department of Fish and Game uses this information to make local and regional management decisions, and the Pacific Salmon Commission uses the data for coastwide management and stock assessment through the Chinook Technical Committee.

Chilkat River large (age-1.3 and older) Chinook salmon Oncorhynchus tshawytscha inriver abundance and age and sex composition will be estimated using a 2-event mark–recapture experiment in 2022. Event 1 marking is conducted in the lower Chilkat River, and event 2 recapture is conducted in principal spawning areas within the Chilkat River drainage. Data produced from this project includes estimated spawning abundance and age, sex and length compositions of the large Chinook salmon run, and when possible, estimated spawning abundance and sex and length composition of the age-1.2 Chinook salmon run in the Chilkat River drainage. The Chilkat River stock of Chinook salmon is a Pacific Salmon Commission Chinook Technical Committee exploitation rate and escapement indicator stock, and contributes toward the coastwide Chinook model used by the Pacific Salmon Commission to monitor coastwide abundance. Mark–recapture experiments of adult Chinook salmon inriver abundance have been conducted in the Chilkat River drainage since 1991 and resulting escapement estimates have had an average coefficient of variation of 16%, which contributes toward precise stock assessment production estimates for the Chilkat River Chinook stock. As part of ongoing Chilkat River Chinook salmon coded wire tag studies, all Chinook salmon encountered in the mark–recapture experiment of adult Chinook salmon inriver abundance will be examined for missing adipose fins, an indication that fish may be tagged with a coded wire tag, information that leads to estimates of juvenile production and marine harvest. These data when used in conjunction with inriver abundance allows full production estimates for the Chilkat stock.

The primary goals of this study are to estimate a) the number of Chinook salmon Oncorhynchus tshawytscha smolt (=50 mm FL) leaving the Stikine River yearly from 2022 to 2024, and b) the mean length and weight of Chinook salmon smolt leaving the Stikine River annually. Additional objectives include estimating the marine harvest and marine survival of adult Chinook salmon returning to the Stikine River from the 2020–2022 brood years and estimating the length and weight of coho salmon Oncorhynchus kisutch smolt that are captured during their outmigration. A modified Petersen 2-event mark–recapture project will be conducted to estimate smolt abundance, and a coded wire tag (CWT) project relying on harvest sampling programs will be conducted to estimate harvest. Length and weight data will be collected during the CWT and event 1 smolt tagging project. Chinook salmon smolt will be marked with adipose fin clips and CWTs each spring. Marked fish will be recaptured through creel, port, and escapement sampling procedures. The Stikine River is 1 of 12 statewide Chinook salmon indicator stocks monitored by the Alaska Department of Fish and Game (ADF&G) and is both an escapement and exploitation indicator stock for the Pacific Salmon Commission (Chinook Research Team 2013, CTC 2021). ADF&G and Fisheries and Oceans Canada (DFO) use these data, along with adult escapement information (described in a separate operational plan), to make terminal and regional management decisions, and the PSC uses these data for coastwide management and stock assessment through the Transboundary and Chinook Technical Committees.