Effectiveness of different release strategies for adult Atlantic salmon in the restoration of endangered populations
Atlantic salmon populations throughout much of Atlantic Canada, including Newfoundland, have been in steady decline in recent decades. Many populations depend now on the conservation initiatives, whereby captive fish, reared in a hatchery from eggs to maturity, are released into rivers to supplement declining wild populations. However, concerns have been raised that the fish reared in artificial conditions differ in behavior in some situations from their wild counterparts, potentially decreasing their spawning efficiency and the survival rate of their offspring. A modified approach, consisting of capturing fish from the wild at smolts (juveniles migrating to the ocean, typically 2-3 years old) and rearing them from that point to mature adults, is being adopted to attempt to mitigate the effects of hatchery rearing. It is hoped that by releasing fish that have been influenced by natural selection and have previous wild exposure that their spawning performance in the wild will be improved. Various release strategies have been considered, yet little research has been undertaken to determine the most effective method for successful for rehabilitation. This project proposes to examine the effectiveness of adult release strategies to supplement Atlantic salmon populations by determining the spawning efficiency of captive and wild-exposed adults. It also aims to determine the behavior of captive-reared fish in situations where release strategies have shifted from supportive breeding to rehabilitation for near extirpated populations. This project will benefit conservation efforts by enhancing our knowledge about the spawning behavior of captive fish released into the wild. Such knowledge allows release initiatives to be more efficient and therefore of greater assistance to remaining wild populations.
