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.
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.
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, since 1976. A mark-and-recapture program ran from 2000 to 2004, and in 2005 and 2006, the Alsek sockeye population was estimated using tissue sample and catch information from the commercial sockeye fishery in Dry Bay as well as the weir counts. By recommendation by the Northern Fund Committee in 2008, a statistically valid sampling strategy that would provide the foundation for reconstructing sockeye and Chinook returns to the Alsek River was completed. Based on this model, it was proposed that funding be provided to analyze sockeye tissue samples collected in the commercial sockeye fishery in Dry Bay (up to 750 per season), to reconstruct the Alsek sockeye runs as described in Gazey’s analysis.
The Waanukv/Owikeeno watershed historically supported one of the largest sockeye populations in BC, currently supports some of the largest Chinook salmon found in the eastern Pacific and has unknown numbers of coho, pink and chum salmon. Prior to implementing the DIDSON and ARIS sonar monitoring systems on the Waanukv River annual estimates of Chinook and sockeye
escapements to the Waanukv/Owikeeno watershed were highly uncertain. The 2012-19 projects have provided the first reliable escapement estimates for Waanukv Chinook since the mark-recapture studies conducted in the 1990’s. The 2014-19 projects have provided the first estimates of the total sockeye escapement to the Owikeeno watershed that were based on quantitative daily counts for the entire sockeye run. Historical escapement estimates for Waanukv Chinook were derived from deadpitch surveys and estimates for Rivers Inlet Sockeye were derived by expanding visual escapement estimates for a few of the tributaries to Owikeeno Lake where spawners could be seen. The results from this project will be used to refine escapement goals and direct restoration and enhancement efforts for each salmon species.
This project proposes to continue an assessment program to estimate the survival and exploitation rates of an outer Central Coast chum stock at McLoughlin Creek (Bella Bella). Production from the Heiltsuk CEDP hatchery at Bella Bella has sustained this stock to a point where it has been able to consistently support both a commercial and FSC harvest in recent years. Starting in brood year 2008, production from this facility was doubled to 2M fed fry released. Returns in recent years have suggested outer coast chum may be surviving at a higher rate than inner coast chum stocks. This project will estimate the survival and exploitation rate of this stock, which can inform both hatchery production as well as fishery management decisions for both inner and outer Central Coast chum stocks. Years 1 and 2 (2012 (2011BY)), 2013 (2012BY) of this project consisted solely of juvenile salmon marking, while year 3 (2014 (2013BY)) was the first and only year with both juvenile marking, as well as adult return assessment components. Years 4-6 (2015-2017) consist solely of assessment of adult returns.
To counter recent reductions in federal funds, and to provide adequate non-federal matching funds this Northern Fund grant is used to augment the existing Alaska Department of Fish & Game Chinook salmon program budget by providing funding for: (1) analysis of data for use by the Chinook Technical Committee (CTC), the Transboundary Technical Committee (TTC) and for other relevant Pacfic Salmon Treaty activities; and (2) analysis of aerial survey, age, sex, and length composition, mark-recapture, smolt, and harvest data for South East Alaska indicator stocks.
Coho salmon returning to the Taku River pass through an offshore troll fishery before entering inside waters where they encounter seine, drift gillnet, and recreational fisheries. After entering the river, the remaining coho salmon encounter drift/set gillnet fisheries in Canada. Such a resource is worthy of a stock assessment program that directly estimates production parameters such as harvest, escapement, exploitation rate, smolt production, survival rates and brood year production. This project will provide annual estimates of escapement necessary to refine escapement goals and forecast runs. Improved escapement goals and run forecasts along with inseason abundance estimates allow implementation of abundance-based management. These combined efforts in-river along with adult sampling programs in the various marine fisheries allow detailed stock assessment analyses.
Funding of this proposal will augment the existing joint Canada and US coded wire tagging programme and serve to provide the resources to meet the Stikine River chinook and coho salmon smolts tagging objectives. The data derived will be used to determine the distribution, run timing, marine survival, and magnitude of marine catches of adult Stikine River chinook salmon, and distribution and run timing adult Stikine River coho salmon. This project is directly linked to the requirement in Annex IV, Chapter 1, paragraph 3(a)(2&3) of the PST to develop and implement abundance-based management regimes for Stikine chinook and coho salmon.
NF-2015-I-3 Etherton (Boyce)
Hydroacoustic programs have been conducted on the Fraser River at Mission, B.C. by the International Pacific Salmon Fisheries Commission (1977-1985) and the Pacific Salmon Commission (PSC; 1986 to the present) to estimate gross upstream passage of Fraser River sockeye salmon. The estimates of daily salmon passage provided by the hydroacoustics program, combined with information from test fishery, stock identification, and catch monitoring programs are used in models to provide estimates of stock abundance, timing, and escapement that are vital to the in-season management of Fraser River Sockeye Salmon.
Following years of discrepancies between the Mission and spawning ground estimates investigations have been undertaken to determine the causes of the discrepancies between these two estimates. As part of the investigations into these discepancies DFO conducted a 5-year experimental program from 1993-1998 at Qualark Creek to design, test and perfect specialized in-river equipment and analytical protocols for riverine acoustic measurements. When Qualark was in monitoring mode in the 1990’s, the pattern of upstream passage tended to track that at Mission, but occasionally showed noticeable differences.
DFO reactivated the Qualark Hydroacoustic Site in 2008 to test the feasibility of the site for estimating salmon abundance with dual-frequency imaging sonar (DIDSON). The daily salmon flux has been estimated in-season using a DIDSON system on each bank of the river between 2008 and 2016. Assessing the performance of the Qualark program through these operational years, DFO has concluded that the site at Qualark is an excellent location for acoustic enumeration of salmon flux in the Fraser River. The site has the ideal characteristics for detecting and tracking Sockeye Salmon as they move upstream, and produces reliable in-season estimates of salmon flux.
Qualark’s sampling system includes 2 DIDSON acoustic units, deployed one on each bank of the Fraser River and operated 24 hours per day during the period of Sockeye Salmon migration. The sampling system also includes integration of catch data from the the daily test fishing operation conducted at the Qualark site on the Fraser River by the Yale First Nation. Daily salmon migration flux is derived by simple time expansion of sub-sampled salmon flux over 3 acoustic data range bins.
The primary goals of the Chilko River Chinook Salmon Mark-Recapture Project are to develop and estimate the spawning abundance that meets or exceeds the Chinook Technical Committee data standard for escapement indicator stocks. Specifically to determine:
1) estimates of spawning escapement by age and sex that will, on average, attain a coefficient of variation (CV) of 15% or less on the spawner estimates; and
2) consistent estimates that are asymptotically unbiased.
Additional objectives include bias testing of application and recovery data, and improving the efficiency of the study in-season and annually.