Monster Seminar Jam - Where in the ocean are they? Chinook and coho salmon ocean migration patterns inferred from coded wire tag recoveries
Dr. Laurie Weitkamp, Res. Biologist, Conservation Biology, NWFSC Newport Research Station
The coded wire tag (CWT) database contains detailed information on billions of Pacific salmon released from hatcheries or smolt traps and recovered in the North Pacific Ocean. I used this goldmine of information to examine spatial and temporal variation in marine migration patterns of hatchery and wild Chinook and coho salmon, based on recoveries of 1.8 million CWTed salmon in coastal areas from southern California to the Bering Sea. Both species show distinct region-specific recovery patterns, which often have surprisingly abrupt boundaries. Chinook salmon are generally recovered further from their stream of origin than are coho salmon and have more wide-spread distributions. Multiple run types of Chinook salmon (e.g., spring, summer, fall runs) originating from the same region also exhibit different migration patterns, suggesting a large genetic component to the patterns. These recovery patterns were remarkably stable between years, although ocean age influenced Chinook recovery patterns, with older fish recovered further from the stream of origin than younger fish. Most CWT data used in this analysis came from hatchery fish, however recoveries of tagged wild populations indicate similar patterns as nearby hatcheries, consistent with the fact that most hatchery stocks are locally derived. Easy access to release and recovery information for millions of salmon across a vast geographic area provides a unique opportunity to examine fine-scale variation in migration patterns, yet is only one of many possible uses of the CWT database.
Date and Time:
October 25, 2007,
10:30 am - 12:30 pm