Once juvenile salmon are adapted to living in saltwater, they begin their long journey out towards the open ocean. This pelagic migration is the least known about phase of the Pacific salmon’s life cycle. It is very difficult to follow large numbers of fish into the far reaches of the deep and expansive North Pacific Ocean.
The recent Pacific Ocean Shelf Tracking (POST) Project applies acoustic tagging and telemetry technology to study the life history of Pacific salmon from their freshwater habitats (in select rivers) out over the continental shelf in the North Pacific. Juvenile salmon are caught and implanted with acoustic tags in their freshwater habitat and then released and tracked as they journey out into the ocean. Tracking data reveals the direction, speed, and timing of movements of individual salmon, and, in some cases, it can also reveal where and when mortalities are occurring in the open ocean. This information will be critical for scientists and managers to start linking environmental conditions with regions where mortality is high in this pelagic phase of their life cycle.
There are 7 species of Pacific salmon: Sockeye (Oncorhynchus nerka), Coho (Oncorhynchus kisutch), Chinook (Oncorhynchus tshawytscha), Chum (Oncorhynchus keta), Pink (Oncorhynchus gorbuscha), Steelhead (Oncorhynchus mykiss), and Coastal Cutthroat (Oncorhynchus clarki clarki). Each with a life history that has evolved from a unique combination of environmental pressures related to foraging, protection and reproduction. Present day abundances of these species has been affected by changing oceanic conditions as well as freshwater habitats.