Tag Archives: Chinook

Automating procedures for the forecasting of terminal run and escapement of Chinook, coho and chum salmon stocks using open-source statistical software

The annual exercise of forecasting terminal run or escapement is a critical aspect of management and conservation of salmonids coastwide. This project involves the completion of an automated computer program (henceforth called “ForecastR”) relying on the open-source statistical software R to generate age-specific forecasts using a variety of generic models including (i) simple and complex sibling regressions with the ability to include environmental covariates, (ii) time series models such as ARIMA, exponential smoothing, and naïve models, and (iii) mechanistic models such as average return rate models that depend on auxiliary data such as the number of outmigrant juveniles, the number of hatchery fish released or the number of spawners.


Chinook Salmon Escapement Estimation to the Skeena River Using Genetic Techniques

The Skeena River is host to the second largest aggregate of Chinook salmon in British Columbia. While the aggregate is a PSC escapement indicator stock, there are no biologically based escapement goals for this population. This project produces an annual escapement estimate for the Skeena River Chinook aggregate and provides information on the stock components that make up the Chinook return to the Skeena River. The project consists of genetic analyses of samples from Chinook salmon caught at the Tyee Test fishery in 2021. The project uses samples and data from two independent programs, the Tyee Test Fishery and the Kitsumkalum mark-recapture program. Chinook salmon scale samples will be collected from the Tyee Test Fishery and the DNA from the samples will be compared against genetic baselines from Skeena Chinook salmon populations. The proportion identified as Kitsumkalum Chinook will be expanded to generate escapement estimates for the Skeena River aggregate using the mark-recapture estimate of escapement for the Kitsumkalum population.



Burman River Chinook Salmon Mark-Recapture

Concern for West Coast Vancouver Island (WCVI) natural Chinook currently limits PSC fisheries in Southeast Alaska, the Haida Gwaii recreational fishery and particularly the Area F troll fishery in northern British Columbia and troll fisheries and some recreational fisheries on the WCVI. Although the Burman River is enhanced, the population is of sufficient size to estimate the escapement with precision, and thermally marked otolith sampling provides an estimate of the naturally spawned fraction.
The program will estimate the escapement of adult Chinook salmon to the Burman River, a PSC Chinook escapement indicator, using both closed population and open population mark-recapture techniques refined between 2009-2014. The project will also quantify age, sex and origin compositions. Estimates of abundance of the thermally marked hatchery fraction combined with a precise escapement estimate will provide important information to verify and support the WCVI Aggregate ratio estimation project by providing an independent reference point (the Burman River Chinook hatchery fraction, independent of Robertson Creek Hatchery stock) in the northern WCVI area.



Recovery Enhancement of Kilbella-Chuckwalla Chinook

Rivers Inlet Chinook are harvested in recreational fisheries, commercial and subsistence fisheries in BC and Alaska, and some of the largest Chinook salmon caught in marine waters originate from Rivers Inlet streams. This project is consistent with the 3rd goal of the Northern Fund, specifically, to enhance wild stock production through low technology techniques using capacity in existing facilities. This Kilbella-Chuckwalla  Chinook enhancement project that will promote production for a wild stock that is currently well below its production potential without creating any long-term operational obligations.

Genetic-Based Abundance Estimates for Snohomish River Chinook Salmon

This project, begun in 2012 by the Washington Department of Fish and Wildlife under the Sentinel Stocks Program to estimate the abundance of Chinook salmon spawners and effective breeders in the Snohomish River, continues today in partnership with the Tulalip Tribes of Washington using trans-generational genetic mark recapture (tGMR) and trans-generational rarefaction curve analysis (tRC). Additional objectives are to partition the genetic-based abundance estimate for natural spawning Chinook by origin, sex, and age, and assuming adequate data are acquired, and to develop a redd expansion calibration factor to adjust historical (or future) redd-based escapement estimates.
Funding is requested to collect and genotype subyearling offspring of the previous brood year, and to collect carcass samples from spawners in the fall. The Snohomish River basin is comprised of two Chinook salmon populations: the Skykomish River summer Chinook population (which includes Skykomish, mainstem Snohomish, and Pilchuck River) and the Snoqualmie River fall Chinook population. We expect to deliver tGMR and tRC abundance estimates for both populations for each brood year that is successfully sampled.

Abundance Estimates for Stillaguamish River Chinook Salmon Using Trans-generational Genetic Mark Recapture

The primary objective of this trans-generational genetic mark-recapture (tGMR) project is to: 1) estimate the abundance of Chinook salmon spawners and effective breeders in the Stillaguamish River above the smolt trap site using genetic abundance methods. The secondary objectives of this study are to: 2) estimate the natural spawning Chinook salmon abundance by origin (hatchery or natural), sex and age, and 3) estimate a redd expansion calibration factor from historic redd-based escapement estimates and possible future redd counts. The data collected for this project also provide a genetic baseline for these population estimates, a genetic (parentage-based) estimate of the proportion of hatchery-origin spawners, and an estimate of relative reproductive success of hatchery spawners, because carcasses are classified by origin. Genetic sampling will be conducted during the fall spawning period, and smolt trapping will be conducted during the following spring.



Alsek Chinook Run Reconstruction

Since 1976, weir counts have been made on the Klukshu River, part of the Alsek River system, by the Department of Fisheries and Oceans (DFO) in co-operation with the Champagne-Aishihik First Nation. In 2007, the weir counts at Klukshu, in conjunction with Chinook catches from the test fishery at Dry Bay, were used to estimate the Alsek Chinook population. The results were encouraging, and by recommendation by the Northern Fund Committee in 2008, a statistically valid sampling strategy that would provide the foundation for reconstructing the Chinook return to the Alsek River was completed. Based on this model, it was proposed that funding be provided to analyze Chinook tissue samples collected in the commercial sockeye fishery in Dry Bay (up to 500 per season), to reconstruct the Alsek Chinook runs as described in Gazey’s analysis. The project was carried out successfully in 2014, but there has not been enough fish in 2015 and 2016.

N14-I32 Alsek Chinook Run Reconstruction 2014

NF-2014-I-32 Huebschwerlen


Terminal Abundance of WCVI Chinook Salmon

Chinook salmon stocks originating from the West Coast of Vancouver Island (WCVI) contribute significantly to the ocean harvests in fisheries in Southeast Alaska and northern British Columbia, as well as being of prime importance to near-shore fisheries along the WCVI itself. Consequently, commercial and sport fishermen, as well as First Nations up and down the coast have a vested interest in the status of WCVI Chinook salmon. Management agencies and organizations responsible for fisheries in Southeast Alaska, northern British Columbia, and along the WCVI have need of stock status information concerning WCVI Chinook salmon.
The overall goal of this project is to estimate the aggregate terminal returns of WCVI hatchery and natural origin Chinook salmon, including catch plus escapement inside the surf line such that the estimates are asymptotically accurate and have a CV of 15% or less. This will be achieved through 1) the first comprehensive assessment of catch plus escapement along the WCVI, and 2) refinement of the ‘driver stock’ approach for estimating aggregate terminal return from a distant fishery.
The “driver stock” approach was first developed through the Sentinel Stock Program, and is based on the assumption that an indicator stock (or stock group) experiences the same exploitation and maturation rates as the aggregate. If the assumption holds, the incidence of this indicator stock group in an ocean fishery (using information such as CWT, otolith, DNA) and in its terminal area would have the same ratio as the catch of the indicator stock group in the same ocean fishery to its terminal run size. When using a single CWT stock, estimating terminal run size is simple. However, given the complexity of the WCVI stock aggregate and terminal WCVI fisheries, the key assumptions of the method – i.e. that maturation rates and exploitation rates are constant across the WCVI aggregate, were not met.
The purpose of this project is to 1) improve the precision of the terminal return estimates of natural and hatchery origin chinook salmon along the WCVI, 2) quantify the variation in maturation, exploitation rates, abundance across the WCVI aggregate, and 3) use the additional information to refine the application of the driver stock approach to the WCVI aggregate through development of a Bayes method. These results will benefit existing stock reconstructions and forecasts in the assessment of the WCVI Chinook salmon stock complex.

Atnarko River Chinook Escapement Estimation

The Atnarko River was identified as a potential escapement and exploitation rate indicator for Central BC early summer Chinook, and in 2009 the Atnarko River Chinook stock was proposed as an exploitation rate indicator. It was funded under the Coded Wire Tag (CWT) Improvement program, and the purpose of the five-year mark-recapture program was to improve escapement estimates for early summer Chinook.
Since then, the program has met the data standard of a coefficient of variation (CV) of 15% or less. Continued mark-recapture estimates on the Atnarko River will build on the information thus far. The project will estimate the escapement of Chinook salmon and generate estimates such that the fraction of CWT fish is known relative to the wild and/or unmarked escapement, and this data is essential for Chinook run reconstruction calculations. This program is part of a comprehensive group of programs on Atnarko River Chinook salmon that includes the production of Chinook fry and CWT application (under separate submission to the Northern Fund) and terminal fishery monitoring.