How do age-of-release and genetic matching of parents impact return rates of Connecticut River Atlantic salmon
The Connecticut River Atlantic Salmon Restoration Program (CRASRP) has stocked the Connecticut River with Atlantic salmon (Salmo salar) fry and smolts since 1967. In 1996, the CRASRP began using microsatellite DNA loci to genetically match unrelated fish for parental pairs in order to preserve maximum genetic variation in the population and increase survival. This study compared historic return rates of fry and smolts to see which life-stage produced higher return rates. The cost of fry and smolt returns was calculated to determine cost-effectiveness. To see if genetic breeding improved survival, return rates and percent eye-up were compared before and after 1996. Eye-up was also correlated with parental relatedness among family groups to see if more distantly related parents produced better embryo survival. Smolt stockings yielded significantly greater return rates than fry stockings and smolts were more economically efficient. Return rates of smolts and fry were significantly lower after 1996. Eye-up was slightly better after 1996, but more distantly related parents did not result in better eye-up. In order to obtain higher return rates, hatcheries should put more effort into stocking smolts. The analysis of the genetic breeding program was inconclusive. Low return rates likely result from poor marine survival.