Revisiting the marine migration of US Atlantic salmon using historical Carlin tag data

The development of a fishery for Atlantic salmon (Salmo salar) in the sea at West Greenland in the early 1960s prompted the start of a US tagging programme in 1962. Between 1962 and 1996, more than 1.5 million salmon from New England rivers, primarily hatchery-reared smolts, were tagged and released. Overall, the rate of tag recovery was 0.55%, with 23.2% of the tags recovered from Canada, 26.0% from Greenland, and 50.8% from the United States. A generalized additive model was used to analyse marine survival based on returns of tagged salmon to the Penobscot River. The month and year of release, sea age, smolt age, and environmental variables, such as the North Atlantic Oscillation (NAO) and Atlantic Multidecadal Oscillation (AMO) indices and local sea surface temperatures (SSTs), were assessed to explain the variability in the return rate. The AMO and NAO indices, SST, sea age, and time across years all affected survival assessed in terms of returns to the Penobscot River. The results provide information to support the management of Atlantic salmon stocks on a spatial and temporal scale in US rivers and the fishery at West Greenland.