Growth Rate Modulation in spring Chinook salmon supplementation

A major focus of current actions under Northwest Power and Conservation Council (NWPCC) and Bonneville Power Administration (BPA) programs is the support of multiple supplementation programs to assist in recovery 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 2004).

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 4 central objectives in various states of progression in contract year 2023 as noted in parentheses next to each Objective:  

Objective 1) (Continuation)

Background:  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-now retired). 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 was 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 are reported in annual and final contract reports, at scientific conferences and in peer reviewed publication(s).  

During the previous (2022) contract period we published the first of two manuscripts in peer review describing this investigation in Transactions of the American Fisheries Society entitled:  "The effect of variation in ration and dietary lipid on precocious male maturation in Chinook Salmon:  a production scale hatchery experiment.

FY 2023 -Adult returns from this production scale hatchery experiment are now complete.  During this contract period we will continue analysis of all outmigration CWT and PIT 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 compiled during this contract period in a draft manuscript for submission to the Canadian Journal of Fisheries and Aquatic Sciences for peer reviewed publication.

Objective 2) (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 CY2020-2021 period 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 (molecular testicular indicator of maturation status).  These factors will be evaluated for their utility as early indicators of jack maturation status 1 year prior to spermiation.  

Final enumeration of jack maturation status in this experiment was conducted during the termination of the study in summer 2021 at a time when maturation status could  be indicated via simple testicular morphology (GSI).  Final enumeration of maturation rates was compared with rates determined via physiological indicators measured in autumn (~10 months before spermiation) and spring (~6 months prior to spermiation).  Since all fish were PIT-tagged individual growth profiles could 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.  During this contract period all demographic and physiological data will be analyzed and compiled and iterpreted for a draft manuscript to be published in a peer reviewed publication (journal TBD).

Objective 3 (Continuation)

Leavenworth National Fish Hatchery partial water re-use (Partial Reuse Aquaculture System or PRAS) vs. conventional raceway spring Chinook salmon comparative evaluation

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 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 2022 we conducted a comparative evaluation of conventionally reared (raceway) and PRAS reared spring Chinook salmon at LNFH with BY2020 "canary" fish transferred for the first time to the new system.  Fish were evaluated for smolt and maturation physiology at a single sampling point in April 2022.   This information was used to develop the full production evaluation over the next 3-4 brood years. In this contract period we will continue monitoring fish from year 1 of a 3-4 year (Brood year 2021-2024 released in 2023-2026) evaluation trial at LNFH in cooperation with USFWS staff comparing conventionally reared (raceway) vs. PRAS reared fish for growth, smolt development, early male maturation, stress, and juvenile and adult survival.

Objective 4 (Continuation)
Walla Walla Hatchery Spring Chinook monitoring and evaluation

Indigenous spring Chinook were extirpated from the Walla Walla River in the mid to early 1900s and efforts to reestablish a Chinook population are being led by the Walla Walla Spring Chinook Hatchery Program (WWHP) and are outlined in the Walla Walla Spring Chinook Hatchery Master Plan (2008). The main objectives of this Plan are to:

1.    establish self-sustaining natural populations in the South Fork Walla Walla River, Mill Creek, and Touchet River,
2.    provide non-tribal and tribal fisheries in the subbasin, and
3.    develop a localized brood stock.

The WWHP and BPA recently constructed a new hatchery facility on the South Fork of the Walla Walla (SFWWH) to aid in these efforts. This program is co-managed by the Confederated Tribes of the Umatilla Indian Reservation (CTUIR), the Oregon Department of Fish and Wildlife (ODFW), and Washington Department of Fish and Wildlife (WDFW) and will produce up to 500,000 yearling spring Chinook annually. In order to evaluate the effectiveness of the SFWWH rearing strategy and its overall contributions to the larger Walla Walla Basin goals, the Walla Walla Hatchery Monitoring and Evaluation Plan (2018) outlines four hatchery monitoring priorities:

1.    Smolt-to-adult survival (Total Recruitment),
2.    In-hatchery survival,
3.    Ecological and genetic effects, and
4.    Minijack rates.

As pointed out in the ISRP Review (2015), post release quantification of minijack rates could “shed light on the apparently high rate of loss of hatchery smolts (nearly 60% loss) enumerated at the downstream trap” as well as “help the proponents evaluate the impact of the project on natural origin fishes”.

In FY 2022 in cooperation with the CTUIR we initiated a multi-brood year Walla Walla Chinook salmon smolt quality evaluation.

In FY2023 we will complete a first and initiate a second year (of 3-4) of smolt quality and physiological evaluation of brood year 2021-2024 (release year 2022-2026) Walla Walla spring Chinook salmon. Fish are reared in circular flow through tanks at the Walla Walla Fish Hatchery, located on the South Fork of the Walla Walla River. Fish are currently being reared on a “naturalized” feeding regime with a size target at release of 10 fish/lb (45g). Fish are allowed to volitionally release directly into the Walla Walla River for three or four weeks before being flushed out at the end of April. Fish will be sampled from 2 circular tanks at five different time points that span from summer to spring. These five time points (August, October, January, February, and April) are optimal as they allow us to calculate growth rates as well as obtain a seasonal profile of smolt development. Data to be collected at these time points include size, condition factor, whole body lipid, and smolt development (via Na+/K+-ATPase enzyme activity). At the final sampling we will also collect plasma from male fish to assess rates of early male maturation (11-ketotestosterone -11-KT).
  
Reference

Artificial Production Review Evaluation (APRE) 2004.  Available at:  https://www.nwcouncil.org/sites/default/files/2004_17.pdf

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.