Read about NSRAA’s salmon research here: 2024 Crawfish Inlet Chum Homing Technical Report
NSRAA’s Evaluation Program is responsible for the collection and analysis of various fish husbandry, hatchery return, and commercial fishery data. The program deals largely with adult returns and tracks and analyses a variety of data that is used in making critical in-season management of fisheries and run utilization. Post season analysis generates estimates of survival, fishery contributions, forecasting future returns, and as feedback for evaluating various rearing and release strategies for all NSRAA projects. The program also maintains several databases relating to NSRAA’s salmon releases, returns, and economic value of commercial and cost recovery harvests. Various summaries from these databases are available in the Data Section on this website.
The collection of this data requires a synthesis of rearing, release, and return information from all our projects. Quality assurance and a robust sampling program are conducted each year at each of NSRAA’s return sites and many fisheries within the region. During the peak weeks of the fisheries, NSRAA’s Evaluation staff can be found on the docks, at processing plants, on the water, or at the hatcheries collecting otolith, scale, coded-wire tag (CWT), sex, weight, and length data on tens of thousands of chum, Chinook, and coho salmon.
Sex ratios and age structure from the terminal fisheries are particularly helpful in assessing run timing. Similarly, the origin of thermally marked hatchery fish intercepted offshore and in state sponsored test fisheries are invaluable for determining early run strength and whether a surplus over brood stock needs might be available for a specific hatchery.
Work is based out of the Sitka office which includes our Evaluation Program Laboratory, equipped to read both scales and otoliths. Otoliths collected across the region are processed and analyzed here using a modular grinder to expose the inner layers of the sagittal otolith and examined under microscope. A laminated impression of each scale is examined with a microfiche or microfilm scanner. Thermally marked otoliths are also analyzed in this laboratory prior to release of juvenile smolts/fry, from each of our projects for quality assurance. Evaluation staff will coordinate the collection of “voucher” specimens in conjunction with ADF&G. The representative samples of voucher otoliths examined by ADFG become available in the Voucher Summary Report (link to ADFG page), a database of all salmon species marked by all hatcheries throughout Alaska.
While NSRAA samples many adult fish for CWT’s and does have the capacity to dissect and analyze these tags, CWT sampled fish are sent to the Alaska Department of Fish and Game (ADF&G) Mark, Tag, and Age laboratory in Juneau. Data is then uploaded and queried from the Mark, Tag, and Age Lab database.
Tagging operations must also occur annually at each of our facilities that release coho or Chinook smolts. These operations are conducted via manual injection of microscopic coded-wire tags (CWT). A CWT is a small piece of stainless-steel wire about 1 millimeter long that is injected into the snout of a juvenile salmon. The tag contains a unique code that identifies the individual or group as part of a specific hatchery release site. Each year, NSRAA staff manually tag between 700,000 and 800,000 coho and chinook smolts using Mark IV injectors and Quality Control Devices manufactured by Northwest Marine Technology. This work usually encompasses the majority of the summer and fall months while fish are quickly growing in freshwater. Due to complicated logistics associated with remote salmon hatcheries, in 2022 NSRAA Maintenance staff retrofitted a cargo trailer to serve as a mobile tagging trailer thereby streamlining and improving the tagging process.
Other special projects that the Research and Evaluation Program undertake can include:
- Environmental monitoring including benthic and zone of deposit surveys for ADEC compliance
- Fish pathology
- Water testing for ADEC compliance
- Generating reports for ADF&G, NSRAA board of Directors, and other industry related groups
NSRAA also conducts and funds various Research projects which investigate a wide range of topics relating to salmon fisheries and biology to help us make informed, prudent decisions as fishery managers.
ONGOING STUDIES:
Hidden Falls Hatchery-Chatham Strait Predator Abundance Survey
To determine the cause of declining marine survival of salmon produced at Hidden Falls Hatchery, a multiyear study began in 2021 to assess the composition and biomass of pelagic predators in vicinity to the hatchery and surrounding fish release locations. Acoustic surveys and rod and reel sampling occur relative to fish release timing. Carbon isotope analysis is also a component of this study; predatory fish that have consumed hatchery fry will exhibit a “signature” that is specific to the terrestrial protein-based commercial fish feed, and an estimate can then be made of predatory effectiveness.
Homing and Imprinting of Crawfish Inlet Hatchery Chum Fry
In an effort to learn more about hatchery fry imprinting and homing fidelity, since 2023 NSRAA is monitoring the outmigration patterns of hatchery chum fry post release as well as examining the water chemistry and amino acid profiles of streams within the outmigration corridor and that of the hatchery incubation water source. Furthermore, in cooperation with the Sitka Sound Science Center, University of Alaska, and NOAA Fisheries, NSRAA is exploring the feasibility of utilizing amino acids derived from cultivated kelp macroalgae as a tool for improving homing efficacy in chum salmon. NSRAA has also been conducting spawner surveys in West Crawfish to evaluate the hatchery donor rate to the West Crawfish Northern Southeast Outside (NSEO) ADFG Index Stream. Our data to date indicates very low hatchery donor stray rates (<1%), and proportion of hatchery origin spawners in the stream is a function of distance from the tideline.
Since the early 2010’s, NSRAA has utilized permitted net pen towing as a predator avoidance maneuver just prior to releasing fish. Since these fish were uniquely tagged by release group, we have also applied an opportunistic method of comparing coded-wire tag recoveries by release group in terminal and non-terminal areas for examining homing behavior among treatments of coho salmon released from Hidden Falls Hatchery.
Pink and Chum Hatchery Wild Study
A 10-year study with the Sitka Sound Science Center, Alaska private non-profit aquaculture associations, ADFG, NOAA and UAF to understand the effects of hatchery pink and chum straying in Southeast Alaska and Prince William Sound. Components of the study include examining genetic stock structure of pink and chum, determining degree of annual straying of hatchery fish, as well as the impacts of straying on fitness (productivity) of wild salmon. Home page for the Alaska Hatchery Research Project. This study was concluded in 2023.
Keta River Chinook broodstock Development for Zero-check Production, cooperation with NOAA at Little Port Walter Research Station
NSRAA’s Research and Evaluation Department is currently undertaking several studies associated with the refinement and amelioration of zero-check Chinook production, and development of a new Chinook broodstock (the Keta River stock) with a natural propensity and ancestry for producing zero-check offspring. Zero-check (or “ocean-type”) Chinook are released from the hatchery as a subyearling rather than the one-check or “stream-type” life history strategy most seen in Southeast Alaskan salmon hatcheries. Because the time spent reared in the hatchery is of shorter duration, a zero-check is a much more cost and resource efficient smolt to produce. Historically with established Southeast Alaskan Chinook broodstocks, such as the Andrew Creek, hatchery staff have had difficulty achieving consistent marine survival and meeting in-hatchery performance benchmarks with zero-check fish. In 2013, the Keta River stock was selected by NOAA and ADFG as the ideal candidate for development of a new Chinook broodstock source that exhibited the natural propensity for producing zero-check offspring, and for being a large, fast-growing stock that recruits into the troll fisheries well. Brood year was the first year the stock was brought into the hatchery for experimental propagation and development.
NSRAA has partnered with NOAA Fisheries Little Port Walter Marine Station on development of the Keta River stock, and other zero-check production improvement strategies. In 2023 and 2024 a collaborative smoltification study was undertaken to determine optimal saltwater entry timing by measuring ATPase and blood chloride levels between the Keta River and Andrew Creek Chinook stocks. Results indicate that the Keta River stock had lower ATPase activity levels, higher sodium and chloride concentrations in the blood, and higher survival rates at smaller fish sizes than the Andrew Creek stock. These results are encouraging given the Keta River stock’s ancestral traits and it confirms the stock to be an appropriate fit for propagation within an enhancement hatchery under a zero-check rearing regime.
Beginning in 2025, Hidden Falls Hatchery will release the first brood year of Keta River stock Chinook at a location other than Little Port Walter, and for the purpose of fisheries enhancement, thus we celebrate entering into the second phase of broodstock development!
PAST STUDIES:
Salmon Lake Coho Weir Monitoring
In 2007, NSRAA took over operation of the Salmon Lake weir to fulfill permitting requirements for the Sawmill Creek Hatchery. Additionally, Medvejie Hatchery transitioned to using Salmon Lake coho as more suitable broodstock source for its coho production at Medvejie and Sawmill Creek. To monitor wild stock escapement as well as ensure hatchery fish were homing appropriately, NSRAA and ADFG cooperatively operated a weir on Salmon Lake outflow to allow wild fish passage and intercept hatchery strays. This monitoring project was concluded in 2021.
Previous studies and projects have revolved around understanding adult and juvenile chum movement throughout Sitka Sound, such as acoustic tagging of adults, fry migration monitoring, and evaluation of chum fry food habits post release. Additionally, substantial work went into pioneering the fisheries technology of utilizing hanging lakes for coho production and consequential establishment of new terminal harvest areas. This work also entailed lake fertilization, and limnological and ecological analysis of large freshwater lakes in Southeast Alaska.
