Fisheries, Subsistence, and Habitat
Publications Searchable Database
Search Again| Division: | Sport Fish |
| Title: | Revised biological escapement goal for the sockeye salmon stock returning to the East Alsek-Doame river system of Yakutat, Alaska. |
| Author: | Clark, J. H., G. F. Woods, and S. Fleischman |
| Year: | 2003 |
| Report ID: | Alaska Department of Fish and Game, Special Publication Series No. 03-04, Anchorage |
| Abstract: | Available information on age compositions, escapements, and harvests of sockeye salmon Oncorhynchus nerka returning to the East Alsek-Doame river system located southeast of Yakutat, Alaska, during the years 1972–2001 was collated. This information was used to develop annual run reconstructions for the years 1972–2001 and to develop a brood table of estimated escapements and age-specific total returns (recruits) for brood years 1972–1997. These data were subsequently used to estimate a spawner-recruit relationship. Analysis of residuals of the stock-recruit relationship demonstrated a trend with a decrease in stock productivity in the 1990s. It is hypothesized that the lack of flooding and resultant reduction in quality of spawning habitat is directly responsible for this reduced productivity. Insufficient escapement contrast, too few data points and a clumping of data points available around the replacement level prevented traditional stock-recruit analysis of the information from the lower production years of the 1990s. Instead, the replacement level was directly estimated. Next, the average ratio between escapements predicted to provide maximum sustained yield fisheries and replacement levels for other studied stocks of sockeye salmon in the Yakutat area was calculated. This average ratio was multiplied by the estimate of replacement to provide a point estimate of the escapement level predicted to provide for maximum sustained yield from the East Alsek-Doame river system stock of sockeye salmon under the reduced productivity experienced by the stock since the early 1990s. From this calculation, a revised biological escapement goal of 13,000 to 26,000 sockeye salmon counted during a peak survey of the East Alsek-Doame river system is recommended. It is recommended that this goal be considered interim and be updated in 2005. Further, it is recommended that the stock-recruit data be updated each year to evaluate productivity status and help determine if the stock dynamics have stabilized at the level observed for brood years 1991–1997. Lastly, recommendations are made to conduct mark-recapture experiments to estimate total escapements for this stock of sockeye salmon. |
| Keywords: | sockeye salmon, Oncorhynchus nerka, East Alsek River, Doame River, brood table, biological escapement goal, maximum sustained yield, spawner-recruit relationship, catch-age analysis |