Abstract
We describe temporal changes in the genetic composition of a small anadromous A tlantic salmon ( S almo 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 ( N b ) and the generational effective population size ( N e ) 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 N e estimates, suggesting that mature male parr are significantly increasing N b and N e over the study period. Spawning as parr appears to be a viable and important strategy in the near absence of adult males.