A new study led by Lia Chalifour used salmon ear bones (otoliths) and genetic fingerprinting to confirm the importance of the Fraser estuary for juvenile Chinook salmon.
Using tiny salmon ear bones, or otoliths, the researchers were able to demonstrate that Chinook salmon from Harrison River rely on the Fraser estuary for one to two months while they feed and grow. These findings underscore the critical nature of this habitat for the persistence and recovery of Chinook salmon.
Harrison River Chinook used to be the most productive Chinook salmon population in the Fraser, but has been declining for generations and is now considered threatened by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC).
Knowing now that Chinook salmon rely on estuarine habitat as juveniles, we must work to protect and restore this estuary.
“This study shows that young Harrison River Chinook rely heavily on the estuary, and in particular the fresh and brackish marsh on the Fraser delta, before they enter the ocean” said Dave Scott, Raincoast biologist and co-author on the paper. “Since the vast majority of these habitats have already been lost or degraded, this stage may be a bottleneck that reduces their productivity”.