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 2019. Event 1 capture and marking will be conducted in the lower Chilkat River, and event 2 recapture will be conducted in principal spawning areas within the Chilkat River drainage. Data produced from this project will include spawning abundance of large Chinook salmon, age and sex compositions of the run, and when possible, age-1.2 abundance and length composition in the Chilkat River drainage. Chilkat River Chinook salmon are an exploitation rate and escapement indicator stock for the Pacific Salmon Commission Chinook Technical Committee, and it has been proposed that this stock be included in the coastwide Chinook salmon model used by the Pacific Salmon Commission to monitor coastwide abundance. Mark-recapture experiments have been conducted in the Chilkat River drainage since 1991; escapement estimates for 1991-2018 have an average coefficient of variation of 14%, which contributes toward precise stock assessment production estimates for the Chilkat River Chinook salmon stock. As part of the ongoing Chilkat River Chinook salmon coded wire tag studies, all Chinook salmon encountered in the mark-recapture experiment will be examined for adipose fin clips and the presence of a coded wire tag, which can be used for estimating juvenile production and marine harvest. Data collected from this project will be used to create full production estimates for the Chilkat stock.

Estimates of Chinook salmon Oncorhynchus tshawytscha spawning escapement will be summarized for 2021 in 11 Southeast Alaska river systems. Chinook index salmon systems include: Situk River, Alsek River, Chilkat River, Taku River, King Salmon River, Stikine River, Unuk River, Chickamin River, Blossom River, Keta River, and Andrew Creek. Spawning escapements will be estimated using aerial and foot surveys, mark-recapture studies, and weirs. The Alaska Department of Fish and Game and Fisheries and Oceans Canada use these data, along with age composition data to make terminal and regional management decisions, and the Pacific Salmon Commission uses these data for coastwide management and stock assessment.

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.

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.

A creel survey will be conducted to estimate sport angler effort, catch, and harvest of large (≥75 cm mid eye to tail fork length) early- and late-run Chinook salmon in the lower Kenai River between the Warren Ames Bridge (river mile [RM] 5.1) and Slikok Creek sanctuary area (RM 18.6). Creel survey estimates will be geographically stratified in relation to the RM 13.7 Kenai River Chinook salmon sonar to provide angler effort, catch, and harvest of large Chinook salmon. A standardized inriver netting project will be conducted in the Kenai River at RM 8.6 to index abundance and estimate the age, sex, and length (ASL) composition of large early- and late-run Chinook salmon. Inseason estimates of Chinook salmon catch and harvest, used in conjunction with sonar passage estimates, inseason catch rates, and the length of returning Chinook salmon from the inriver netting study are used by fisheries managers for inseason management decisions to achieve escapement goals. This plan covers the creel survey and inriver netting studies for the 2021–2023 seasons.

Transgenerational genetic mark–recapture (tGMR) methods will be used to estimate the spawning abundance of Chinook salmon Oncorhynchus tshawytscha at the Chilkat and Unuk Rivers in 2020 and 2021, respectively. Tissue samples from adults returning to the Chilkat River were collected in the summer of 2020 and from parr rearing in the Chilkat River in the fall of 2021. Lab work and data analysis will be completed in the winter of 2021–2022. Similarly, tissue samples from adults returning to the Unuk River were collected in the summer of 2021, and samples will be collected from parr in the fall of 2022. Lab work and data analysis will be completed in the winter of 2022–2023. These studies will be used to determine the feasibility of using tGMR to estimate escapement in Southeast Alaska by comparing tGMR abundance estimates to abundance estimates generated through existing field programs. This operational plan covers the lab and project reporting aspects of these projects. Primary data collection activities are described in the project-specific operational plans.