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.

Previous work have established that yearling hatchery releases of URB fall Chinook salmon (currently a key part of supplementation programs for ESA listed Snake River URB fall Chinook salmon) results in a high proportion of early male maturation. This represents a loss of production of full size anadromous fish and also represent a threat to the maintenance of the genetic integrity of the naturally spawning population. Documented evidence also suggests that yearling releases of URB fall Chinook salmon result in a high proportion of early maturing males in the Yakima and Umatilla Basins. Counts of age-2 upstream migrants at Three Mile Falls Dam on the Umatilla River suggest that significant minijack production was evident at the initiation of yearling fall Chinook salmon releases in the Umatilla River (Umatilla Fall Chinook HGMP). While potentially ubiquitous and common, little effort has been put forth to either enumerate or evaluate minijack production; thus, the problem is largely (and conveniently) ignored.


This project has five central objectives in various states of completion and initiation in 2020-2021 as noted in parentheses next to each Objective:  

Objective 1)

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 2019-2020 contract period we compiled a draft manuscript for peer reviewed publication describing the four years of this study.  In CY2020-2021 we will further refine this manuscript for submission to a peer reviewed journal.

Objective 2)

Refine rearing protocols to reduce minijack rates and optimize smolt development in URB Fall Chinook salmon.  In CY 2013 we completed the rearing portion of a laboratory scale experiment at the Northwest Fisheries Science Center (NWFSC), Seattle exploring the effects of alterations in emergence timing and growth rate (via ration manipulation) on life-history development and associated physiology in Umatilla River URB Fall Chinook gametes obtained from the Umatilla (or Bonneville) Hatchery.  This experiment is being conducted with eggs obtained from brood year 2011 adults that returned to the Umatilla River that were acquired during the  FY11 contract period and continued through final sample analysis in spring 2014. The objectives is being conducted by Don Larsen and Brian Beckman of NOAA Fisheries, Seattle, WA. The effectiveness of this research will be monitored through physiological profiles for growth and seawater tolerance compiled for each treatment group throughout the experiment and final age-1 and age-2 maturation surveys conducted during and at the end of the experiment. During the 2019-2020 contract period results from this study were compiled in a preliminary draft peer reviewed publication.  

During the 2020-2021 contract period this draft will be further refined for publication.  

Objective 3) (Continuing work)

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).   In previous contract periods we conducted minijack surveys from of Idaho hatchery spring Chinook salmon at McCall, Sawtooth, Springfield Pahsimeroi, and Rapid River hatcheries, ID.

During CY 2020-2021 we will complete sample analysis from these surveys and 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.

Objective 4) (Continuing work).

Part I
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 CY 2019-2020 CY. This manuscript will be finalized and submitted to a peer reviewed journal in CY 2020-2021.

Part II
Test Null Hypothesis: Part II. McCall Integrated vs. Segregated Growth Study
Null Hypothesis: Integrated and Segregated line McCall Hatchery spring Chinook salmon reared under a common feeding regime will have similar rates of growth and minijack rates.  This study reared PIT-tagged McCall Hatchery, ID spring Chinook salmon form integrated and segregated lines in the same rearing tanks and monitor individual growth rates by tracking PIT tagged animals that compete with each other for feeding opportunities under High and Low Growth  regimes. The experimental portion of this study was completed in FY 2016.  Continued data analysis, interpretation and manuscript preparation will be conducted during CY 2020-2021.

Objective 5) (Continuing Work)

Study title:  The interaction of genetic and environmental effects on minjack and jack production in hatchery spring/summer Chinook
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 and 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 will continue to be reared according to the experimental design and surveyed for minijack maturation rates.  After all minijacks are enumerated and removed, treatments will continue rearing to the jack stage.
  
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.