Last updated on 13 August 2013
Alaska Department of Fish and Game (ADF&G) achieves accurate harvest monitoring through its fish-ticket/e-landing reporting system. However, stock-specific harvest estimates are often not possible in areas where salmon migrate as mixed stocks through a multi-district corridor (Prince William Sound and Southeast Alaska, for example).
In the main pink salmon production regions of Alaska, Southeast Alaska and Prince William Sound, escapement is primarily monitored through the use of aerial surveys. Aerial surveys in Prince William Sound cover approximately 20% of regional pink and chum salmon streams, which represent 75–85% of total regional escapement. IMeanwhile, Southeast Alaska chum salmon escapement trends are monitored through annual surveys of 81 index streams representing over 1200 streams where chum salmon have been observed to spawn.
Recently, ADF&G has made considerable effort to improve the quality of escapement data for chum salmon in Southeast Alaska, including conducting hatchery straying studies, carrying out concurrent aerial and foot surveys in order to ground truth aerial escapement estimates, and allocating funding toward helicopter surveys to facilitate better viewing of fish in the stream.
The ADF&G escapement monitoring methods and estimates of wild harvest, in principle, allow for estimates of wild run size and productivity for particular management districts.
Last updated on 10 August 2013
The 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.
Escapement goals for eight Southeast Alaska chum salmon stocks were established in 2009 and have never been lowered. Concerns that no accountability for hatchery chum salmon present in escapements might confound escapement goal analyses have been partially addressed, as recent studies indicate that accounting for hatchery chum salmon in escapements would not result in meaningful changes to escapement goals. Stock specific brood and return estimates are not available for chum salmon, but there is separate stock management by space (regional stream aggregates) and time (summer and fall run stocks). While choice of indicator stocks and management aggregates of stock groupings (for which single escapement goals are established) are considered scientifically justified, there are also unrepresented stocks (Northern Southeast Inside and Taku River fall run stocks).
Prince William Sound currently has escapement goals in place for five districts. Goals for all districts were lowered once eleven years ago (in the 2002 regional escapement goal review). During the subsequent escapement goal review in 2005, the Southeastern district goal was lowered again. No further goal lowering has occurred since.
The FishSource method gives salmon fisheries lower scores on Criterion 2 (Escapement Goals) if escapement goals are being lowered repeatedly in association with missed management objectives. 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 10 Aug 2013
Performance against escapement goals varies by region and district fishery. In Southeast Alaska, due to the absence of escapement goals for chum salmon until 2009, it is more meaningful to look at escapement trends for stock units over the past 15 years rather than escapement performance against goals.
According to our analysis using the method of Geiger and Zhang (2002), Southeast Alaska chum salmon escapements have declined by over 50% in 1997-2011 for 6 of 10 stocks. Of the remaining four stocks. two stocks showed trends of considerable increased abundance and two had insufficient data for analysis, but were presumed to have declined by greater than 30%.
In the Marine Stewardship Council’s (MSC’s) fourth surveillance report (Moody Marine 2011), it was noted that, according to ADF&G’s assessment, (which looked at a larger number of smaller stock units) most chum salmon stocks in Southeast Alaska are in a period of stable or, in some cases, increasing abundance. Trends for other Southeast Alaska salmon species may suggest that declines in chum salmon escapement are attributable in part to conditions that are not fishery related. Furthermore, variations in survey routines in recent years may have contributed to counts in recent years that are biased low relative to earlier in the time period. Nonetheless, given the available data, it is not clear that the productivity of the stock units at the management scale has been maintained.
In Prince William Sound, meanwhile, district-specific escapement objectives were repeatedly missed in 1996-2010 by two of the five stocks for which escapement is managed to achieve objectives. Performance has improved in the last half of the time series, with most of the misses occurring in the first eight of those fifteen years.
The third most productive region for chum salmon, Westward Alaska, includes the component districts of Kodiak, Chignik, and the Alaska Peninsula. In Kodiak, escapement goals for the two stocks managed to achieve goals (Kodiak Mainland District and Kodiak Archipelago aggregate) have been met in the past several years. However, prior to that, the record is more mixed. Kodiak Mainland district stock escapements fell below the escapement goal a total of 7 times between 1998 and 2012.
Meanwhile, in the Alaska Peninsula and Chignik, escapement goals during the recent 15-year period have mostly been achieved consistently. The weakest performances were by the Alaska Peninsula stocks of Unimak District and the Northwestern District, each of which failed to meet their goals a total of five times during the 15-year period of 1998-2012.