Last updated on 17 July 2008
Virtually 100% of the landed catch in the troll fishery is reported with a fish ticket reporting system and compliance is complete and monitored. However an estimated 14% of reported catch in the Southeast Alaska troll fishery (which accounts for 40% of Alaskan Chinook salmon harvest) is lost to incidental mortality, including sublegal fish (shakers) killed in the regular retention fishery and both legal and sublegal fish killed in the non-retention (coho) fishery. Programs to monitor incidental mortality rates are inconsistent.
Hatchery stocks and many wild stocks coastwide are coded-wire tagged. Many of these programs have been on-going since the mid-1970’s and provide a wealth of information on distribution of various stocks in coastwide fisheries. The CTC currently measures the exploitation rate on 48 tagged stocks and abundance of 31 indicator stocks in the Chinook Model. Genetic studies have also been conducted to confirm the stock composition of Alaska troll catches.
A variety of methods are used to count escapements for the over 70 Alaskan Chinook salmon stocks managed to achieve escapement goals. There are continuing efforts to improve on escapement monitoring methods. The escapements of all major Chinook salmon stocks in the Southeast Alaska troll fishery are measured and documented in annual reports of the Chinook Technical Committee (CTC) of the Pacific Salmon Commission. This fishery is managed under the auspices of the Pacific Salmon Treaty. The CTC documents the escapements of 50 stocks outside of Alaska and 11 Transboundary and Southeast Alaska Stocks.
Last updated on 9 March 2016
Virtually 100% of the landed catch in the troll fishery is reported with a fish ticket reporting system and compliance is complete and monitored. However an estimated 14% of reported catch is lost to incidental mortality, including sublegal fish (shakers) killed in the regular retention fishery and both legal and sublegal fish killed in the non-retention (coho) fishery. Programs to monitor incidental mortality rates are inconsistent, although Chinook model results do provide estimates of incidental mortality.
Hatchery stocks and many wild stocks coastwide are coded wire tagged. Many of these programs have been on-going for several decades and provide a wealth of information on distribution of various stocks in coastwide fisheries. The CTC currently measures the exploitation rate on 48 tagged stocks and abundance of 31 indicator stocks in the Chinook Model.
Genetic studies have also been conducted to confirm the stock composition of Alaska troll catches .Between 1998 and 2003, ADF&G used a mixed-stock analysis and the available coast-wide baseline of allozyme genetic markers to identify the genetic stock composition of the commercial troll fishery (see Crane et al. 2000 and Templin et al. 2011). The 1998 study was to evaluate the feasibility of using genetic markers to estimate the composition of Alaska troll catches and the 1999–2003 studies expanded sampling to look at time and area differences in stock composition of troll catches. Samples were obtained from the winter, spring, and summer troll fisheries, with area strata also associated with the estimated stock composition. Templin et al. 2011 found that the Middle/North Oregon Coastal and Upper Columbia River Summer and Fall stocks combined accounted for 30–33% of the harvest. This compares well with the CTC (2012b) analysis which estimated that these stocks in the model account for 36% of the 1985 – 2010 all Alaska gear catch. The genetic results also found important contributions from Thompson River (Fraser Early), West Coast of Vancouver Island, Washington Coastal and Southern Southeast Alaska stocks, which confirmed the coded wire tag results of the Chinook model.
The Southeast Alaska troll fishery harvests a mixture of Chinook salmon stocks distributed coast-wide from the Situk River near Yakutat to northern and central Oregon Coastal stocks (Templin et al. 2011; CTC 2012a). The escapements of all major Chinook salmon stocks in the fishery, including 50 stocks outside of Alaska and 11 Transboundary and Southeast Alaska Stocks, are measured by respective individual state, local, and tribal agencies. The data is documented and reviewed by the Chinook Technical Committee (CTC).The escapements of all major Chinook salmon stocks in the Alaska troll fishery are measured. The CTC documents the escapements of 50 stocks outside of Alaska and 11 Transboundary and Southeast Alaska Stocks. A variety of methods are used to count escapements, including. foot and aerial counts of spawners, redd counts, carcass counts, dam and weir counts, area under the curve expansions, radio telemetry, and mark recapture estimates using visual counts, coded wire tags, and genetic markers (CTC 2012a).
The CTC began the documentation of escapement trends in 1987 (CTC 1988) as part of the effort to assess the rebuilding status of stocks. In 2009, PSC established a 5-year Sentinel Stock Program to develop better estimates of escapement for certain key stocks or stock groups (CTC 2011c). Currently about $2 million (US) is budgeted each year to improve escapement estimates.There are continuing efforts to improve on escapement monitoring methods.
Last updated on 17 July 2008
Alaska Department of Fish & Game (ADF&G) managers may set two types of target reference points: Biological Escapement Goals and Sustainable Escapement Goals. Biological Escapement Goals are generally based on a more extensive and complex analysis of stock performance in light of escapement observations and are considered to represent the escapement with the greatest potential for maximum sustainable yield. In contrast, Sustainable Escapement Goals represent an escapement level that is known to provide for sustained yield over a 5- to 10-year period.
Regional escapement goal review occurs once every three years and ADF&G recommendations for stock-specific goals of either type go before the Board of Fisheries afterward for consideration and approval. The Board of Fisheries may substitute its own Optimum Escapement Goal for either a Sustainable Escapement Goal or a Biological Escapement Goal if the Board finds a need to do so to meet competing objectives.
The Chinook Technical Committee (CTC) also reviews and formally accepts escapement goals for those stocks harvested in the Southeast troll fishery. There is bilateral (US and Canadian) participation in CTC escapement goal approval proceedings.
Chinook and sockeye stocks account for over 50% of the 300 escapement goals currently in use in Alaska. All Southeast Alaska Chinook escapement goals are BEGs, having undergone extensive monitoring and analysis, including through the CTC approval process (all Southeast Alaska goals have been reviewed by the CTC). In contrast, in the Arctic-Yukon-Kuskokwim (AYK) fishery, only three of 26 stocks have BEGs, and the rest of the stocks are managed to achieve SEGs. Reductions to 13 out of 25 existing Yukon River and Kuskokwim Management Area escapement goals have occurred at least once, and several additional Kuskokwim River goals are likely to be lowered during the next review. In one case, goals were lowered twice (Middle Fork Goodnews River). Escapement goal reductions were associated with missed management objectives for the East Fork Andreafsky River stock (Yukon Management Area) and the Middle Fork Goodnews River stock (Kuskokwim Management Area).
There are instances where well-intentioned managers have set escapement goals too high, and after careful analysis conclude that by lowering the goals there will be a better balance between future needs (conservation) and the immediate benefits to the fishery participants (yield)—which is the balance managers are attempting in a sustained fishery. However, there can also be instances when escapement goals are lowered without a careful consideration of these tradeoffs.
Last updated on 17 Jul 2008
The greatest cause for concern with respect to performance against reference points lies with the Arctic-Yukon-Kuskokwim (AYK) region, where depressed stock status has been noted for the last decade. Economic ramifications of associated fishery closures were severe to the extent that both areas were among three Alaska salmon fisheries granted federal disaster status by the United States Department of Commerce in 2012.
Four Chinook salmon stocks in the AYK region failed to achieve escapement goals in eight or more of the recent 15 years, or at least five of the past seven years. Among these are the Kwiniuk River and Shaktoolik River stocks in the Norton Sound Management Area, which failed both the 15-year and 7-year benchmarks on the basis of 1997-2011 data. The Shaktoolik River goal has been recommended for elimination in 2013. While the Shaktoolik River Chinook salmon stock is a stock of yield concern, the Kwiniuk River Chinook salmon stock has not been recommended as a stock of concern. In addition, roughly 25% stocks region-wide are noted as lacking escapement goals.
The other district fishery where federal disaster status was granted in 2012 is that of Upper Cook Inlet. Six stocks in that district are currently exhibiting chronic inability to meet escapement and/or yield targets.
As for Alaska-origin stocks harvested in the Southeast Alaska troll fishery, of the 11 Southeast Alaska escapement systems, 10 had decreasing trends in escapement from 1999-2011, two of which (Stikine River and Situk River) exhibited annual decreases over 5%. The Situk is the most northern Chinook salmon stock in Southeast Alaska and very few Situk fish are caught in the troll fishery. The Stikine River is managed under provisions of the Pacific Salmon Treaty Transboundary Agreement and few Chinook salmon from this system are caught in the troll fishery (an average of 4% of the total run). Although most river systems in Southeast Alaska are currently exhibiting decreasing escapements, only 9% of the time do escapements fall below escapement goal ranges.
Last updated on 9 March 2016
Last updated on 09 Mar 2016
Coast-wide management relies on the Chinook model, a well-reviewed analytical method of tracing the harvests of Chinook salmon stocks through the fisheries. Hatchery contribution methods are also well documented and accepted.
The Chinook model has been the main analytical tool of the Chinook Technical Committee (CTC) since negotiations began in the early 1980s (see CTC 1986 for early assessment of rebuilding program). The model program (written in Quick Basic) was fully documented by the CTC Analysis Work Group (1991), and subsequent modifications have been documented in the annual exploitation rate analysis and model calibration reports of the CTC. Currently there are 25 fisheries and 30 stocks or stock groups in the model. Model outputs include exploitation rate indices, survival rate estimates, Abundance Indices for aggregate abundance-based management fisheries, incidental mortality estimates, and stock composition estimates for fisheries.
The process for calculating the Alaska hatchery add-on and statistical basis for the risk adjustment factor was documented in a series of papers (Clark and Bernard 1987; ADF&G 1991; Bernard and Clark 1991). The CTC reviewed these procedures (CTC 1992) and concluded that although the statistical foundation of the add-on is sound, a number of assumptions need to be verified. Furthermore, the CTC noted that directing more effort towards spring stocks could increase harvest pressure on stocks comingled with these hatchery stocks. The PSC has nevertheless accepted the add-on documentation since its inception.
The trends in escapements of the largest contributing stocks to the Southeast Alaska troll fishery vary, and there are some geographic clusters of declines. Of the 10 stock groups which contribute to more than 1% of the troll catch or greater than 5% of the total harvest that occurs in the fishery, four showed declining trends, but no trends were greater than 5% per year. The average trend in escapements was a 0.7% increase per year in 1999–2011.
Last updated on 17 July 2008
Stock status is assessed based on multi-year escapement trends and performance against escapement goals (see synopsis under reference point section and more detailed information under district profiles). There are a number of stocks of regulatory concern in the AYK, Cook Inlet, and Kodiak districts. See "Recovery Plan" section for more detail.
Last updated on 17 Jul 2008
Chinook harvests by the commercial fishery in Alaska have not varied much over the past 90 years, with the last ten decadal averages ranging from about 600,000 to 800,000 Chinook salmon. On the other hand, significant use of Chinook salmon in Alaska occurs in sport and subsistence fisheries and those harvests have increased substantially. In several areas of Alaska, Chinook harvests in the commercial fishery are restricted to provide for other users. Harvest declines in the last few years related to fishery curtailment in response to depressed stock status are visible in Figure 2.
The FishSource method examines 15-year trends in wild stock harvest at the district fishery scale. Meaningful (≥5%) annual declines in wild harvest are visible in the Arctic Yukon Kuskokwim fishery and in the Copper River fishery.
Stock status is assessed based on multi-year escapement and harvest trends and abundance modeling. See synopses under Reference Points, Trends and Recovery sections.
Wild Harvest Trends
The wild component of the troll catch has been relatively stable in 1999–2011, exhibiting a 4% annual increase over those years (Figure 2). However, target catches are set in PSC negotiations and a number of other criteria determine catch levels, including harvest- sharing considerations.
Figure 2: Wild harvest trends in the Southeast Alaska Chinook troll fishery, 1999–2011. Using the robust regression method of Geiger and Zhang (2002), an annual rate of increase of 4% was detected. Hatchery contributions to harvest, which were subtracted from total harvest, included estimates of untagged hatchery fish.
The 2013 preseason, all-gear, allowable catch for Southeast Alaska is 176,000 fish, 90,000 fish lower than the 2012 target catch and the second lowest target catch dating back to 1999 (CTC 2012a; ADF&G 2013b). Recent modifications in preseason estimation of the Abundance Index (Carlile, pers communication) and lower abundance of Chinook salmon stocks contributing to Alaskan fisheries are responsible for the lower target catch. Reduced harvest in the Southeast Alaska Chinook salmon troll fishery is occurring amidst a backdrop of statewide concern regarding the health of Chinook stocks. ADF&G has prepared a research plan intended to fill gaps in current knowledge of stock status and dynamics in order to explore reasons for declines noted among multiple Alaskan Chinook salmon stocks (ADF&G 2013c).