Data from: Mature male parr contribution to the effective size of an anadromous Atlantic salmon (Salmo salar) population over 30 years

We describe temporal changes in the genetic composition of a small anadromous Atlantic salmon (Salmo salar) population from South Newfoundland, an area where salmon populations are considered threatened (COSEWIC 2010). We examined the genetic variability (13 microsatellite loci) in 869 out-migrating smolt and post-spawning kelt samples, collected from 1985 to 2011 for a total of 22 annual collections and a 30 year span of assigned cohorts. We estimated the annual effective number of breeders (Nb) and the generational effective population size (Ne) through genetic methods and demographically using the adult sex ratio. Comparisons between genetic and demographic estimates show that the adult spawners inadequately explain the observed Ne estimates, suggesting that mature male parr are significantly increasing Nb and Ne over the study period. Spawning as parr appears to be a viable and important strategy in the near absence of adult males.Ecological and Microsatellite dataThis tab-delimited file contains all the allele scores for 869 samples across 13 microsatellites, along with the relevant demographic data.MEC-12-1011_Ecological and Microsatellite data.txtParr sampling dataThis is field-recorded data of the sex, maturity and measurements of 100 parr. Some parr were too small and could not be sexed in the field. Sampling occurred via electrofishing in collaboration with the Department of Fisheries and Oceans, St. John's, Newfoundland.MEC-12-1011_Parr data.tx