Growth Rate Modulation in spring Chinook salmon supplementation

Reasonable and Prudent Alternative (RPA) 63.2 of FCRPS Biological Opinion calls for determining the effects of implementing hatchery reforms on salmon and steelhead populations and RPA 65.2 is focused on estimating Fall Chinook hatchery program effects on productivity. A major focus of current actions under Northwest Power and Conservation Council (NWPCC 2004) and Bonneville Power Administration (BPA) programs is the support of 12 supplementation programs to assist in recovery of 8 ESUs of Chinook salmon and steelhead trout listed as threatened or endangered under the ESA. A significant concern for these programs is that they release fish that are ecologically, genetically, and phenotypically similar to their wild cohorts. In response to this concern, a number of rearing guidelines for supplementation programs have been made in the Artificial Production Review and Evaluation report (APRE).

The primary goals of this project are to assesses the proportion of precociously maturing males and smolt associated physiological development of salmonids  produced in supplementation and conservation hatcheries in the Columbia and Snake River Basins and to conduct both basic and applied research to help revise and develop rearing protocols to reduce unnaturally high rates of precocious male maturation and produce fish with similar physiological, morphological and life-history attributes as wild fish to maximize survival and recovery. Previously, we have identified the prevalence and magnitude of age-2 male maturation (minijack) in conservation and supplementation programs for Spring and Summer Chinook salmon in the Columbia River Basin. In some programs, in some years, 60% of the males produced are destined to mature at age 2. In the Yakima Supplementation program the average minijack rate over 10 years is 41% which is 9 fold the rate we have estimated in wild Yakima River Spring Chinook salmon (Harstad et al. 2014). This represents an obvious loss of production. More insidiously, the minijack phenotype also results in unnatural selection profiles on the smolts released from the hatchery and profound demographic effects on the spawning grounds, ultimately and undeniably altering the genetic structure of the natural populations that the conservation programs were designed to protect. Minijacks represent an ecological presence that may prey on and compete for food and habitat with native stocks. Finally, high minijack rates represent a significant source of error in calculations of smolt-to-adult return rates (SAR's); the central currency for survival estimates throughout the Columbia Basin.

Through this ongoing project we have documented that hundreds of thousands of minijacks are released from hatchery programs each year. These are actually not smolts when released and they rarely return as adults to the spawning grounds. It is essential to quantify their presence prior to release in programs of interest and devise methods to control production of unnaturally high minijack rates. Reduction in the rate of minijack production can lead to direct increases in smolt production and reduction in domestication selection. However, there are significant challenges associated with these efforts as growth profiles that reduce early male maturation often produce small smolts. Numerous studies have shown that smolt size is highly correlated with adult survival. This project is specifically designed to reconcile the paradox presented by these conflicting principles. Key project personnel have conducted experiments that suggest reducing growth rates and lipid deposition in the autumn/winter of the fish’s 1st year will reduce early male maturation rates. In addition, experiments have shown that delaying ponding until March/April can eliminate high rates of age-1 male maturation.

This project has 6 central objectives in various states of completion, continuation and initiation in 2021-2022 as noted in parentheses next to each Objective:  

Objective 1) (Completion)

Improve survival and reduce fitness loss in Columbia River URB Fall Chinook salmon. We will determine rates of minijack production (through measurement of plasma 11-ketotestosterone levels) and associated physiological development including growth, whole body lipid, plasma IGF-1 (endocrine index of growth physiology) and Na+/K+-ATPase activity (enzyme indicator of smolt development) in Umatilla stock URB Fall Chinook Salmon (serving as a proxy for listed Snake River stocks) reared at Bonneville Hatchery for a production scale 2x2 factorial experiment exploring the effects of High and Low Ration and High and Low lipid diet on life-history development over four consecutive brood years (BY's 2010-2013 released 2012-2015). This study will be monitored by Don Larsen of NOAA Fisheries, Seattle, WA  in partnership with co-managers from the Confederated Tribes of the Umatilla Indian Reservation (CTUIR) and Oregon Department of Fish and Wildlife (ODFW- Lance Clarke). Our monitoring effort for this work started in FY 2011 under the final year of the previous solicitation period (FY 07-09 extended to 2010-11) and continued until spring 2015. The effectiveness of this work will be monitored through compilation of physiological profiles for each brood year and treatment group, minijack surveys conducted for each treatment at the time of release, juvenile survival and minijack migration via pit-tag interrogation in the Columbia River hydro by-pass systems and adult ladders and ultimately via adult return rates from 2014-2017. Final results and conclusions will be reported in annual and final contract reports, at scientific conferences and in peer reviewed publication(s).  

During the CY 2020-2021 contract period we compiled a draft manuscript for peer reviewed publication describing the four years of this study.  In CY2021-2022 we will further refine this manuscript for submission to a peer reviewed journal.

Larsen, D.A., Fuhrman, A.E., Harstad, D.L., Venditti, D.A., and Beckman, B.R.  (in revision).  Stock specific variation in the probability of precocious male maturation in hatchery Chinook salmon (Oncorhynchus tshawytscha).  Canadian Journal of Fisheries and Aquatic Sciences.

Objective 2)  (Initiation).  
Adult returns from the production scale hatchery experiment with URB Fall Chinook described in Objective 1 are now complete.  During this contract period we will initiate analysis of all outmigration tag interrogation records and adult return data from this experiment.  We will also analyze all demographic data available describing treatment effects on age structure and sex ratios of returning adults.  This data will be assembled for eventual compilation in a peer reviewed publication.

Objective 3) (Continuation)

Quantification of basin wide Chinook salmon minjack rates.  This objective has historically focused on quantifying long-term minijack rates in Chinook salmon from the Yakima River Supplementation Program and other hatchery spring, summer and fall Chinook populations throughout the Columbia River basin.  Over the course of these studies a major finding is the observation that segregated hatchery populations have reduced minijack rates compared to integrated programs due to domestication selection (Harstad et al. 2014; Larsen et al. 2019).   In previous contract periods we conducted minijack surveys from of Idaho hatchery spring Chinook salmon at McCall, Sawtooth, Springfield (Yankee Fork experimental Chinook), Pahsimeroi, and Rapid River hatcheries, ID.

During CY 2021-2022 we will compile data over all years surveyed for eventual reporting in a peer reviewed publication and to present in a web accessible database for use by regional fisheries managers and researchers.  NOTE:  This database was compiled during the previous contract period and will be updated periodically with new data compiled over the FY2021 contract period.

Objective 4) (Completion).

Test the  Hypothesis:  Spring Chinook salmon sourced from different hatchery stocks with varying degrees of integration and/or segregation reared under identical "common-garden" growth regimes will express different genetically set rates of minijack maturation and diffreent  threshold sizes for initiation of maturation.  This experiment is being conducted with brood year 2014 spring/summer Chinook salmon sourced from approximately 8 separate populations of Snake and Columbia River hatchery Chinook salmon from a mixture of integrated and segregated stocks (Imnaha, OR-integrated, Pahsimeroi, ID-integrated and segregated, Sawtooth, ID-integrated and segregated, Rapid River, ID-segregated, Carson, WA-segregated, Methow, WA-integrated).  The experimental portion of this study was completed in FY2016.  Continued data analysis, interpretation and manuscript preparation was conducted during FY 2020. This manuscript was finalized and submitted to a the Canadian Journal of Fisheries and Aquatic Sciences during FY 2020.  Final publication of this manuscript is scheduled for FY 2021.

Objective 5) (Continuation)

Study title:  The interaction of genetic and environmental effects on minjack and jack production in hatchery spring/summer Chinook salmon.
Test the hypothesis:  Spring Chinook salmon stocks that possess an increased propensity for minijack maturation will also possess an increased propensity for jack maturation.

This is a 2x2 factorial investigation involving captive culture of McCall, ID (high propensity for minijack maturation) and Carson, WA (low propensity for minijack maturation) hatchery spring Chinook salmon at the Northwest Fisheries Science Center under a high and low growth regime to evaluate minijack and jack maturation rates.  This study will also evaluate growth profiles that increase and decrease the propensity for early male maturation (minijack and jack) in stocks with variable genetic thresholds for expressing these life histories in order to develop hatchery rearing regimes for BPA and other sponsored hatchery programs throughout the Columbia and Snake River basins.
During CY 2019-2020 all fish were PIT-tagged and identified to sex using a genetic marker.  All female fish were then removed from the study to decrease tank densities in order to maintain experimental growth regimes.  During the CY2020-2021period treatment groups were reared according to the experimental design and surveyed for minijack maturation rates in Autumn 2020.  At the time of minijack enumeration (FY 2020) and early spring (2021), physiological indicators of jack maturation were collected from a subset of immature male fish.  Factors collected included length, weight, condition factor, GSI (gonadasomatic index) ,plasma 11-ketotestosterone (maturation hormone), pituitary FSH and LH mRNA (molecular indicator of maturation), tests IGF3, and AMH mRNA (testicular indicator of maturation status).  These factors will be evaluated for their utility as early indicators fo jack maturation status 1 year prior to spermiation.  Measurement of these samples will be conducted during FY 2021 contract period.

Final enumeration of jack maturation status in this experiment will be conducted during the termination of the study in summer 2021 at a time when maturation status will be indicated via simple testicular morphology (GSI).  Final enumeration of maturation rates will be compared with rates determined via physiological indicators measured in autumn (~12 months before spermiation) and spring (~6 months prior to spermiation).  Since all fish were PIT-tagged individual growth profiles will be analyzed for their effect on ultimate maturation status (minijack, jack, age 4+) and used to optimize rearing regimes associated with variation in genotype (McCall vs. Carson) in Columbia basin hatcheries.

Objective 6 (Initiation)

The U.S Fish and Wildlife Service's Leavenworth National Fish Hatchery (LNFH) rears spring Chinook Salmon using intensive fish culture methods. Current compliance permits have directed LNFH to reduce water withdraws and improve effluent discharge. LNFH is facing the choice of either reducing production of spring Chinook Salmon or adopting methods, such as water reuse. LNFH seeks to use Partial Reuse Aquaculture System (PRAS) as an alternative rearing strategy, such that it will uphold tribal trust responsibilities by maintaining current production targets with less flow. This evaluation is to test the effectiveness of a “pilot” PRAS to rear spring Chinook Salmon at LNFH. The pilot system selected uses a total of four circular rearing tanks (two tanks per system) and associated reuse infrastructure housed in a stand-alone building. Additionally, the pilot will evaluate the effectiveness of effluent treatment and determine if aggressive effluent treatment is capable of significantly reducing phosphorus discharge to Icicle Creek. The circular tank system was selected because of suggested benefits of ease in operation, improved fitness to the fish reared in a higher velocity environment, lower flow requirements, and the ability to concentrate fish waste while saving water.

In FY 2021 we will initiate a comparative evaluation of conventionally reared (raceway) and PRAS reared spring Chinook salmon at LNFH.  Fish will be evaluated for smolt and maturation physiology over an initial (Canary test) year and 3 consecutive annual releases.  In FY 2021 we will conduct three sample collection events of the canary fish and assist with development of the three year (Brood year 2021-2023) test evaluation trial at LNFH in cooperation with USFWS staff.
  
Reference
Harstad, D.L., Larsen, D.L., and Beckman, B.R., 2014.  Variation in minijack rate in Columbia Basin hatchery Chinook salmon.  Transactions of the American Fisheries Society. 143: 768-778.

Larsen, D. A., D. L. Harstad, A. E. Fuhrman, C. M. Knudsen, S. L. Schroder, W. J. Bosch, P. F. Galbreath, D. E. Fast, and B. R. Beckman. 2019. Maintaining a wild phenotype in a conservation hatchery program for Chinook Salmon: The effect of managed breeding on early male maturation. Plos One https://doi.org/10.1371/journal.pone.0216168.