Assessing reproductive success of Atlantic salmon in two restoration programs

Restoration programs, including reintroductions and supplementations are often used to offset the continued decline of freshwater fish populations. While frequently implemented, few succeed in establishing self-sustaining populations. Some limitations that are thought to impede the success of these programs often stem from genetic and ecological issues due to carry over effects from a captive setting. These risks often influence the donor populations ability to reproduce in the wild. In this study, we evaluated the reproductive success of Atlantic salmon through genetic parentage analyses from a reintroduction program in two major tributaries of Lake Champlain, USA (Boquet, and Winooski Rivers, NY, VT respectively); as well as four different adult rearing groups (with varying duration of time spent in captivity) from a smolt-to-adult supplementation program and live gene-banking program in the Upper Salmon River, Fundy National Park, NB. We determined that adults which returned to both Lake Champlain tributaries, successfully reproduced in the wild. However, few adults produced the low numbers of surviving offspring sampled in this system. On the other hand, in Fundy National Park, we determined that all adult rearing groups were successful in reproducing in the wild. However, the relative reproductive success of the rearing group that spent the shortest time in captivity was comparable to other groups which spent longer periods of time in captivity. While our results suggested that fish from these restoration programs can reproduce in the wild, adults in both systems had low reproductive success. If this continues over subsequent years, the establishment and long-term persistence of these populations may be difficult to achieve. These studies not only contribute to a greater understanding of the reproductive ability of fish from both programs in the wild, but demonstrate the complexity of these restoration programs and the various factors involved in influencing restoration success. Therefore, these studies emphasize the importance of combining continued monitoring and an adaptive management to promote re-establishment and long-term persistence in restoration programs