Data from ongoing age 2 male maturation assessments of yearling Chinook and Sockeye salmon at hatchery facilities located in the interior Columbia basin

Pacific salmon have diverse life histories including phenotypic plasticity in the age at which males initiate maturation (range 1-6 years).  Both genotype and rearing practices (feed type and rate, rearing temperatures) influence age of maturation.  We have been monitoring age 2 (minijack) precocious male maturation rates at various Columbia River basin hatchery facilities from 1997 to the present. Thus, it is a compilation of over two decades of monitoring minijack rates at hatcheries primarily focused on yearling reared spring, summer and fall-run Chinook salmon but also includes yearling Snake River Sockeye salmon as well. The dataset includes the size (both length and weight) of individual fish at the time of maturation assessment, just prior to hatchery release in the spring as yearling smolts. It was compiled from several studies that examine effects of feed treatments within a hatchery population (lipid content of feed and feed ration) and effects of rearing s..., Maturation status of males was determined via enzyme linked immunosorbent assay  (ELISA) of 11-ketotestosterone (11-KT) levels in blood plasma. See related works for details. 
, Please contact the authors for assistance in interpreting, using or republishing this data. 

Minijack_Database-File with data on individual fish sampled as part of minijack assessments across multiple brood years and hatchery facilities.

Release_Group_Description-File with background information for each release group contained in the Minijack_Database, including rearing and release locations and rearing treatments. 

Hood_River_Rearing-File depicting the rearing of Hood River spring Chinook salmon across several hatchery facilities and acclimation sites for brood years 2008-2017.
, , # Data from ongoing age 2 male maturation assessments of yearling Chinook and Sockeye salmon at hatchery facilities located in the interior Columbia basin

Dataset DOI: [10.5061/dryad.0rxwdbrzn](https://doi.org/10.5061/dryad.0rxwdbrzn)

## Description of the data and file structure

We assessed age 2 male maturation of Pacific salmon (primarily Chinook) at several interior Columbia River hatcheries, starting in 1997. This data set contains size, gender, and maturation (age 2) status determined from plasma 11-Ketotestosterone levels measured just prior to smolt release from hatcheries.

### Files and variables

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### File: Hood_River_Rearing.pdf

**Description:** This file graphically summarizes rearing locations of the Hood River stock fish at Round Butte, Parkdale, and Carson hatcheries, as well as subsequent acclimation at Blackberry, Moving Falls, and Pelton Ladder acclimation sites. See Release_Group_Description.csv for full back ground information.

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#### File: Minijack_Dat..., **Changes after Feb 8, 2021:** We are adding the related dataset for the Deschutes River Chinook salmon rearing study that has been accepted for publication in the North American Journal of Aquaculture (Spangenberg et al. 2026). This study overlaps with the dataset that was previously published, and includes minijack rates, seasonal size data, as well as data on smoltification (gill ATPase levels) and seasonal energy content (measured via percent whole body solid levels).