The US Fish and Wildlife Service is Offering a Cooperative Agreement for Chinook Salmon Escapement Estimation in Togiak River Watershed

PURPOSE:

The primary purpose of this project is to use mark-recapture methods to estimate the total abundance of Chinook salmon and to investigate the effectiveness of aerial surveys to monitor Chinook salmon escapement in the Togiak River watershed. This project addresses the need to obtain reliable escapement estimates for Chinook salmon in the Togiak River that was explicitly requested in the 2008 Request for Proposals for the Monitoring Program. Subsistence harvest of, and spawning and rearing habitat for Chinook salmon in the Togiak River occur within the Federal Conservation System boundaries of the Togiak National Wildlife Refuge. Providing a harvest priority to subsistence users in these waters is mandated under Title XIII of ANILCA.
Additionally, this cooperative agreement will build capacity within BBNA and community for future projects by hiring and training citizens of BBNA villages and/or local residents as research assistants to conduct field sampling. This project is of high strategic importance for the Anchorage Fish and Wildlife Field Office (AFO), BBNA, and Alaska Department of Fish and Game (ADF&G). BBNA will provide local research assistants to assist with weir operation and data collection.
OBJECTIVES:

1. Estimate the proportion of Chinook salmon migrating past a weir on Gechiak Creek;
2. Estimate the abundance of Chinook salmon escaping into the Togiak River watershed such that the estimate will have a 90% probability of being within 25% of the true abundance;
3. Estimate the weekly age and sex composition of spawning Chinook salmon in Gechiak Creek, such that simultaneous 90% confidence intervals have a maximum width of 0.20;
4. Estimate the mean length of Chinook salmon by sex and age;
5. Document Chinook salmon spawning locations in the Togiak River watershed;
6. Evaluate the effectiveness of aerial spawning ground surveys for monitoring Chinook salmon abundance in the Togiak River watershed; and
7. Measure and document water temperature throughout the main stem and lower tributaries in the Togiak River watershed (BBNA).

BACKGROUND

Recent Chinook salmon Oncorhynchus tshawytscha production throughout the region, as well as much of Alaska is in decline. Chinook salmon are important components of valuable subsistence, sport, and commercial fisheries. Assessment of Chinook salmon escapements in Federal waters of Bristol Bay is poor – escapements are accessed via aerial surveys which at best have large variability and have been conducted sporadically in recent years. All of these factors are present for Togiak Chinook salmon, which is the largest subsistence fishery with Federal nexus and jurisdiction in Bristol Bay. Chinook salmon are a high profile species whose management has often been an issue between the Federal Subsistence Program and the state.
A comprehensive investigation of Chinook salmon abundance and distribution within the Togiak River watershed has never been accomplished. Current monitoring of Chinook salmon escapement in the Togiak River watershed is limited to aerial surveys. Aerial survey observations are often plagued by bias and variability caused by variability in salmon run timing, between observer counting ability, weather, water conditions, aircraft characteristics (type, speed, altitude, and pilot experience), and similar factors. Escapement is estimated by expanding visual counts with correction factors. Aerial survey estimates within the Togiak River watershed have not been verified with other methods, and the accuracy with which the observations index abundance is unknown. Chinook salmon escapement estimates have not been calculated since 2005 or were based on partial surveys (Sands et al. 2007).
The Alaska Department of Fish and Game (ADFG) has established an escapement goal in the Togiak River watershed of 10,000 Chinook salmon based on aerial surveys and, through regulations of the commercial fleet (gear and fishing closures), that goal has been regularly achieved from 1996 to 2007 (Sands et al. 2007).
Average estimated Chinook salmon spawning escapement from 1996 to 2005 was 11,862 fish, with an average harvest over the same period of 11,273 fish, representing a 49% exploitation rate. The harvest includes 9,213 fish harvested in the commercial fishery, 902 harvested in the sport fishery, and 1,158 harvested in the subsistence fishery (Sands et al. 2007).
The Office of Subsistence Management, through its strategic planning process identified the need to obtain reliable escapement estimates for Chinook salmon in the Togiak River (OSM 2005). The Bristol Bay Regional Advisory Council has identified the need for improved monitoring of salmon escapement in the Togiak River since 2003 and development of a reliable estimate of Chinook salmon escapement into the Togiak River was explicitly requested in the 2008 and 2010 Request for Proposals for the Monitoring Program. Improving long-term escapement monitoring to include all species of adult Pacific salmon has been identified as a top priority with the Togiak National Wildlife Refuge, Togiak Traditional Council, and the ADFG. Accurate monitoring of Chinook salmon abundance is necessary for managers to maintain adequate escapements to provide for future subsistence needs. Subsistence harvest of, and spawning and rearing habitat for Chinook salmon in the Togiak River occur within the Federal Conservation System boundaries of the Togiak National Wildlife Refuge. Providing a harvest priority to subsistence users in these waters is mandated under Title XIII of ANILCA.
Continuation of this project will provide managers with estimates of Chinook salmon abundance, run timing, and spawning distribution within the Togiak River. This information will allow us to determine if the population can support current exploitation rates in subsistence, sport, and commercial fisheries. Results from this project will be compared to those from aerial surveys and provide the basis to evaluate continued escapement monitoring of this population. To address declines in Chinook salmon production, the Federal Subsistence management strategy for this region should be to provide accurate population assessments in a collaborative working relationship with the State and local stakeholders (Doug McBride, Federal In-season Manager, personal communication). The Anchorage Fish and Wildlife Field Office (AFWFO) proposes to build upon estimates of spawning distribution and run timing provided under Project 08-402 with this proposal to include estimates of spawning abundance as well as further estimates of distribution and run timing for an additional three years.

REASON FOR SINGLE SOURCE:

Continuation – BBNA is the sole organization that is committed and qualified to work cooperatively with Bristol Bay tribes, and state and federal agencies to assist in research, management, and protection of subsistence fishery resources. This project was selected for funding under the Federal Subsistence Fishery Resource Monitoring Program. As such, a competitive proposal was submitted in response to that advertisement for funding. Projects were evaluated on strategic importance, technical merit, administrative competence, and degree of capacity building. Recommendations for project selection and funding were made by an Inter-agency Technical Committee, Subsistence Regional Advisory Councils, and Office of Subsistence Management staff. Final project selection was made by the Federal Subsistence Board.