DOI: 10.5061/dryad.x3ffbg7vk
title: Data from: Age at release affects developmental physiology and sex-specific phenotypic diversity of hatchery steelhead trout (Oncorhynchus mykiss)

description: Most steelhead trout hatcheries increase growth rate during rearing to
 produce and release yearling smolts for harvest augmentation, but natural
 steelhead exhibit variable age of smoltification, so this common rearing
 practice may not be ideal for programs focused on recovering imperiled
 wild stocks; therefore, it is important to investigate and compare
 alternative hatchery rearing methods that promote life history diversity.
 Over six consecutive years, the Winthrop National Fish Hatchery on the
 Methow River, WA reared and released paired groups of age-1 (S1) and age-2
 (S2) steelhead smolts. To understand how the two rearing methods affected
 developmental ontogeny and life-history, fish were sampled prior to
 hatchery release for factors associated with smoltification (size, gill
 Na+/K+ ATPase activity, and a qualitative smolt phenotype) and sexual
 maturation (sex, pituitary and testis mRNA transcripts, gonadosomatic
 index, and plasma 11-ketotestosterone). Our objectives were to quantify
 levels of smoltification and male maturation during hatchery rearing,
 combine metrics to estimate residualism (failure to migrate upon release),
 and compare the treatments by sex. Overall, S2 rearing produced 7.8% more
 smolts and 44-fold (4.4 vs. 0.1%) more precociously mature males than S1
 rearing. Conversely, S1 rearing produced 31.6% more residuals than S2
 rearing. While the proportion of total male residuals was comparable
 between treatments, the S1 treatment produced approximately five-fold more
 female residuals (20.6 vs. 4.2%). Because residuals contribute minimally
 to adult returns and the number of returning adult females is critical to
 the success of salmonid supplementation efforts, developing rearing
 techniques that maximize migration in females is a management
 priority. Physiological assessments are useful for characterizing
 and quantifying the effects and risks of different hatchery
 rearing regimes on steelhead life-history, in addition to providing
 sex-specific guidance to inform and optimize conservation
 management goals in supplementation programs.
description: # Data from: Age at release affects developmental physiology and
 sex-specific phenotypic diversity of hatchery steelhead trout
 (Oncorhynchus mykiss)
 [https://doi.org/10.5061/dryad.x3ffbg7vk](https://doi.org/10.5061/dryad.x3ffbg7vk) ## Description of the data and file structure We collected steelhead trout (*Oncorhynchus mykiss*) from two different rearing treatments at the Winthrop National Fish Hatchery between 2011 and 2015 prior to hatchery release. At the time of sampling, we collected fork length, weight, sex, and a visual index of smolt phenotype. Gill tissue was collected from a subset of each treatment. No further information was collect on female fish. For males, paired testes were weighed and one testis was preserved for histology and the other was preserved for mRNA analysis. Male blood was collected, centrifuged, plasma was removed and stored. Male pituitary glands were dissected and preserved for mRNA analysis. For additional information regarding methods and specific analyses, consult our publication: Age at release affects developmental physiology and sex-specific phenotypic diversity of hatchery steelhead trout (*Oncorhynchus mykiss*). *PLOS ONE* ### Files and variables #### File: WinthropSteelhead\_2011-2015\_AllData.csv **Description:** All data included in our publication. Please consult our publication for more detailed information on terms and methods used. ##### Variables * Fish_ID: Unique fish ID across years, encompassing collection hatchery (WINT), release year (RY####), treatment (S#), and fish number (####) separated by underscores * Fish_Number: Unique fish ID within a single collection year * Length_mm: Fork length measured in millimeters * Weight_g: Body weight measured in grams * Sex: Visually identified sex * Condition_Factor: Calculated from fork length (L) and body weight (W) as condition factor (K) = (W / L^3) x 100,000 * TestisWeight_g: Weight of paired testes measured in grams * GSI: Gonadosomatic index, calculated from testis weight (T) and body weight (W) as GSI = (T / W) x 100 * Log10GSI: log10 transformed GSI * Histo_Stage: Testis histological stage as determined by parameters defined in Middleton et al. 2019 found in the reference section of our publication * KT_ng.ml: Plasma 11-ketotestosterone in ng/ml * Log10KT: log10 transformed KT_ng.ml * fshb: Relative expression of pituitary mRNA follicle stimulating hormone beta-subunit * Log10fshb: log10 transformed fshb * lhb: Relative expression of pituitary mRNA luteinizing hormone beta-subunit * Log10lhb: log10 transformed lhb * amh: Relative expression of testis mRNA anti-Mullerian hormone * Log10amh: log10 transformed amh * igf3: Relative expression of testis mRNA insulin-like growth factor-3 * Log10igf3: log10 transformed igf3 * Smolt_Index: Numerical representation of visually identified smolt phenotype; parr = 1, transitional = 2, smolt = 3, PP = precociously mature male * ATPase_Activity: Gill Na+/K+ ATPase activity measured in umol / mg protein x hour * Raceway: Hatchery raceway the fish was collected from, raceways at this facility are labeled with a letter followed by a number and as such, unique combinations of letter + number equate to a unique raceway * Treatment: Either S1 (fish reared to release at age-1) or S2 (fish reared to release at age-2) * Brood_Year: Year fish were bred * Release_Year: Year fish were collected/sampled * Maturation_Category: Immature, maturing, or mature as defined by the statistical analysis section of our publication * Migration_Category: Residual or migrant as defined by the statistical analysis section of our publication Missing data codes: empty cells. Data may be missing (empty) for a few reasons: 1. Fish identified visually as female in the field only contain data for the following fields: Fish_ID, Fish_Number, Length_mm, Weight_g, Sex, Condition_Factor, Smolt_Index, Raceway, Treatment, Brood_Year, Release_Year, Maturation_Category, Migration_Category. Although, some female fish may contain data for the field "ATPase_Activity" because this metric was subsampled irrespective of sex. Otherwise, not further analysis was conducted on females resulting in empty cells. 2. Data was mistakenly not collected in the field or QA/QC of field or laboratory data resulted in removal from the dataset. 3. Missing field or laboratory data resulted in an inability to conduct certain analyses and therefore cells remain empty. ## Code/software The .csv files can be viewed with a spreadsheet program.