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Marine Salmon Investigations

Pacific Salmon Commission Technical Committee Meetings

Auke Bay Laboratories (ABL) staff and contractors were involved in several bilateral Pacific Salmon Commission (PSC) meetings in January and February 2010. At the PSC post-season meetings held in Vancouver, British Columbia, 11-15 January, John Joyce participated in the Enhancement Subcommittee and full Transboundary Technical Committee (TBTC) discussions, Bill Heard and Michele Masuda were involved in deliberations with the Northern Boundary Technical Committee (NBTC), and contractor Alex Wertheimer was U.S. Co-Chair of the Total Mortality Working Group (TMWG) of the Chinook Technical Committee (CTC). Wertheimer also participated in TMWG and CTC discussions at the annual PSC meeting in February in Portland, Oregon, and Joyce attended a TBTC meeting in Whitehorse, Yukon Territory, in early March. A synopsis of bilateral technical issues for each of these groups is discussed below.

Transboundary Technical Committee
The Transboundary Technical Committee reviewed and discussed research and management activity on Taku, Stikine, and Alsek Rivers during 2009. Catch and management summaries by species and river system were presented for Chinook, sockeye, and coho salmon. The activities include smolt estimation through mark-recapture and code-wire tagging, adult weir counts, foot and aerial surveys, collection of genetic samples for baseline GSI work, and harvest data relevant to overage/underage treaty agreements.

Concurrent to the management summary, the enhancement subcommittee reviewed and summarized sockeye enhancement activity on the Taku and Stikine Rivers. Enhancement of sockeye salmon, now with formalized plans for each river, has been technically challenging and controversial. The plans tie enhancement directly to harvest sharing agreements, so there is a large investment in planning and monitoring enhancement activity. Specific issues related improving success in Taku River enhancement through extended smolt rearing and redesigning egg take strategies to improve Stikine River enhanced production. Most of the enhancement subcommittee’s time during the Whitehorse meeting was dedicated to these panel directed activities.

In addition, committee chairs presented an update on the funding process for the PSC Northern Fund in 2010. Funds from this source went directly to pre- approved continuing NOAA ABL projects for Northern Boundary Sockeye (Jeff Guyon), Southeast Coastal Monitoring (Joe Orsi) and a small allotment to support University of Alaska Fairbanks/NOAA ABL work at Auke Creek (John Joyce). Also discussed were future Northern Fund projects for sockeye salmon enhancement and methods for improving Taku River Chinook salmon in-season management by expanding mark recapture programs.

Northern Boundary Technical Committee
The Northern Boundary Technical Committee meetings focused primarily on two issues: 1) catches of sockeye salmon in 2009 by the United States and Canada along the Dixon Entrance boundary area between Southeast Alaska and northern British Columbia; and 2) implementation of a blind test of known principal sockeye salmon stocks on both sides of the border comparing three analytical procedures. The analytical procedures include both DNA microsatellite and single-nucleotide polymorphism (SNPs) genetic analyses and scale pattern analysis (SPA) techniques for stock identification.

The U.S. Canada Pacific Salmon Treaty allows for specific rates of interception of sockeye salmon originating from Canadian Nass and Skeena Rivers that are caught in Southeast Alaska fisheries called the annual allowable harvest (AAH). To arrive at the appropriate harvest level of these stocks by Alaska fisheries the total annual sockeye runs to both Nass and Skeena Rivers must first be derived by determining the total Canadian catch (including First Nations catches), escapements to the rivers, and the Alaska catch. Sorting this out requires detailed stock composition analysis of sockeye catches on both sides of the border. Historically stock composition of samples from Canadian fisheries has been derived by DNA microsatellite analysis by Fisheries and Oceans Canada (DFO) and by SPA analyses from U.S. fisheries by the Alaska Department of Fish and Game (ADF&G). Presently, however, the ADF&G is planning to shift from SPA analysis to genetic-based SNPs analysis of catch samples from Alaska fisheries. A previous blind test between DNA and SPA analyses of known samples verified the utility of this earlier procedure, hence now the need for a new blind test comparing analyses of all three techniques.

One reason detailed annual stock composition analyses of these fisheries is necessary is that migration patterns vary from year to year, and stock composition of catches in specific fishery openings on both sides of the border fluctuate greatly within season and between seasons. While Nass and Skeena Rivers comprise the two main Canadian stocks, most Alaska stocks involved in these fisheries consist of a large number of much smaller sockeye stocks in the southern part of Southeast Alaska grouped together for analysis as the Alaska composite. Also, in some years depending on landfall patterns and specific migration routes of returning adult sockeye, significant numbers of Stikine River sockeye from central Southeast Alaska, Fraser River sockeye from southern British Columbia, and smaller west Vancouver Island sockeye stocks are also caught in these Northern Boundary fisheries.

A very low forecast for Skeena River sockeye salmon may preclude targeted fisheries on this stock in 2010. Roughly 80% of total sockeye returns to the Skeena River usually come from the headwaters of the Babine River system where a large artificial spawning channel development is the main driver of Babine production. Failure of ocean age-1 sockeye “jacks” to the Babine spawning channels in 2009, usually a dependable forecast tool, has Canadian officials concerned about returns for the coming season.

Total Mortality Working Group
Recent Total Mortality Working Group and CTC meetings have focused on the required analyses necessary to implement a total mortality management regime for aggregate abundance-based management (AABM) fisheries for coastwide Chinook salmon fisheries as called for under the 2008 Treaty agreement. This involves a complicated and lengthy process of developing methods for translating the relationship between nominal landed catches of Chinook salmon and the abundance indexes (AIs) for AABM fisheries into total mortality (TM) units. A CTC model involving stock- specific brood year exploitation rates for indicator stock using cohort analysis procedures provides a variety of stock-specific statistics including exploitation rates and maturation rates that are combined with data on catches, escapements, Chinook non-retention mortality, sublegal mortality from hook and line gear (shaker mortality) and enhancement to provide annual calibrations of the model that determines the appropriate AI for each year. The developed AIs then determine the allowable landed catch (LC) of Chinook salmon for three AABM fisheries (Southeast Alaska, northern British Columbia, and west coast of Vancouver Island) as shown in Table 1 of Annex IV of the Treaty.

Applying TM units into landed catch (LC) equivalents requires careful evaluation and development of a suite of variable metrics including the probability of a fish surviving to maturity in the absence of fishing, converting different types of fishing mortalities into common values within and between gears, and considering relationships between different minimum size limits restrictions in different fisheries. These new metrics subsequently will be used by CTC to calculate the allowable TM for both pre-season and post-season estimates for each AABM fishery along with development of a new revised TM Table 1. This new table will define the allowable catch in each fishery as determined by the annual AI. Significant changes in allowable Chinook harvests in AABM fisheries are possible.

The continued evaluation and refinement of this process is still ongoing by the TMWG with the intention of completion by late 2010 in time for potential application of TM fisheries for Chinook salmon during the 2011 season. Depending on the final outcome of TM management projections, implementation will follow any new Pacific Salmon Commission directives.

By Bill Heard, Michelle Masuda, John Joyce and Alex Wertheimer

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