Since 2020, Chinook salmon in California have been experiencing a thiamine (vitamin B1) deficiency leading to reproductive failure and neurological dysfunction. Thiamine is an essential coenzyme used in metabolic processes that salmon cannot biosynthesize and must depend on dietary intake or absorption for their needs. Lower levels of thiamine in Chinook have been linked to salmon diets dominated by the booming population of northern anchovies which produce the thiamine-degrading enzyme thiaminase. We lead a multi-disciplinary team of scientists to understand the causes, impacts, and mitigation options of this new stressor to California salmon. Actions taken to treat hatchery salmon with Vitamin B1 have reduced reproductive failure and mitigated the threats of this newly emerged stressor on California's endangered winter run Chinook salmon that have been under extreme threat from ongoing multi-year drought conditions. Our team conducts annual egg surveillance monitoring that has detected widespread thiamine deficiency in CCV Chinook salmon in 2020 and 2021, and emerging TDC in Klamath and Trinity River coho salmon in 2021. Through stable isotope analysis of archival tissues (eye lenses and scales) we reconstruct salmon diets linked to TDC. Our research suggests that California’s salmonids are likely to remain at risk of TDC as long as their forage-base is dominated by northern anchovy, thereby adding a new stressor to highly-valued, but already highly-stressed, populations.
California Salmon Thiamine Deficiency Research and Mitigation
Collaborators
Rachel Johnson (Project Contact)
Carson Jeffres (Project Contact)
Project Description
Program
Project Status
Active