Salmon escapement estimates at the Little Waterfall barrier bypass, Afognak Island, Alaska: 1995 - 1998

• Main Authors: Honnold, Steven, Richardson, Jim, Sullivan, Joe
• Format: Dataset
• Language: English
• Published: Gulf of Alaska Data Portal 2013
• Subjects: Afognak Island; spawning habitat; Kodiak Island; pink salmon; barrier bypass; coho salmon; EVOSTC; Exxon Valdez Oil Spill Trustee Council; Oil Spill; Exxon Valdez; Alaska; Pelagic; Fish; Kodiak; Pink salmon
• Online Access: https://dx.doi.org/10.5063/f1j10122; https://goa.nceas.ucsb.edu/#view/doi:10.5063/F1J10122

Surveys were conducted in 1992-93 at Little Waterfall Creek (LWC), Afognak Island, to evaluate instream habitat and potential stock restoration techniques for wild salmon stocks. Data indicated that LWC contained significant amounts of spawning habitat that were underutilized by pink and coho salmon due to an ineffective barrier bypass structure. The project priorities were to renovate the bypass to reduce gradients and design resting pools to minimize water velocity. The bypass renovation was completed in the fall 1995; bypass gradients were reduced from 27% to 17-20% and two additional resting pools and an entrance pool were installed. The steeppass sections were staggered between pools to reduce the velocity of stream flows. The historical performance of the three bypasses at LWC, since installation in 1981, has been significant, increasing average pink salmon escapements from -7,000 to -70,000 fish. The number of pink salmon migrating by way of all three bypasses to spawn in upstream habitat has significantly increased resultant returns; however, regression analysis was driven by the large upstream escapement in 1993. The historical proportion of the total annual pink salmon escapement to migrate upstream has primarily been a function of the design and performance of the largest (most upstream) bypass. Publications: Honnold, S.G. 2001. Little Waterfall Creek barrier bypass improvement: Pink and coho salmon habitat enhancement, Exxon Valdez Oil Spill Restoration Project Final Report (Restoration Project 97139Al), Alaska Department of Fish and Game, Division of Commercial Fisheries, Kodiak, Alaska.