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 site (example: Hood River stock fish reared at three different hatcheries) on fish growth and maturation. Overall, we have found that the prevalence of minijack maturation is variable among hatchery populations (ranging from 0-72% of males) and is significantly influenced by species, stock, life-history type and hatchery rearing practices.

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.