North Pacific Anadromous Fish Commission

Technical Report 17

Table of Contents

Mechanisms, Impacts, and Mitigation for Thiamine Deficiency and Early Life Stage Mortality in California’s Central Valley Chinook Salmon

Authors: 
Nate Mantua, Rachel Johnson, John Field, Steve Lindley, Tommy Williams, Anne Todgham, Nann Fangue, Carson Jeffres, Heather Bell, Dennis Cocherell, Jacques Rinchard, Donald Tillitt, Bruce Finney, Dale Honeyfield, Taylor Lipscomb, Scott Foott, Kevin Kwak, Mark Adkison, Brett Kormos, Steve Litvin, and Iliana Ruiz-Cooley

Abstract Excerpt:
Thiamine Deficiency Complex (TDC) is a nutritional deficiency of thiamine (vitamin B1) recently linked with high mortality of early life stages of Chinook salmon (Oncorhynchus tshawytscha) in California’s Central Valley (CCV) hatcheries. Prior to 2020 TDC had never been diagnosed in California salmon, yet there is some evidence it had gone undetected in the past. In early 2020 hatched fry showed clinical signs of TDC that included loss of equilibrium, lethargy, abnormal swimming, and death between hatching and first feeding (Foott 2020). In spring 2020, we launched an interdisciplinary study to better understand the mechanisms, impacts, and mitigation measures for TDC and early life stage mortality in CCV Chinook salmon. We documented that excessive fry mortality was related to thiamine deficiency. We demonstrated that egg and fry thiamine baths recover ailing fry, and injection of pre-spawn females with thiamine prevented fry mortality and TDC (c.f., Futia et al. 2017). Consistent with previously published research, we confirmed TDC in symptomatic fry with egg thiamine measurements (Harder et al. 2018). Marine ecosystem surveys in the central part of the California Current Large Marine Ecosystem documented an unusually dominant population of Northern anchovy (Engraulis mordax) beginning in 2018 and persisting through 2020. Anchovy have thiaminase (Greig and Gnaedinger 1971; Tillitt unpublished), an enzyme that destroys or degrades thiamine in its consumers, and from published research diets high in clupeid species with thiaminase can result in low egg thiamine leading to TDC. Our gut content analysis found that Anchovy were the dominant prey item for Chinook salmon captured in fisheries off California’s central coast in 2020, making up 97% of the prey items by weight. Other work has documented low thiamine concentration in ocean water off Baja California (south of typical CCV Chinook salmon feeding areas) (Sañudo-Wilhelmy et al. 2012), but we do not yet know the significance of these published water data as it relates to CCV Chinook salmon TDC.

*This is the first paragraph of an extended abstract. Download the full abstract below.

DOI:
https://doi.org/10.23849/npafctr17/92.93.

Citation

Mantua, N., R. Johnson, J. Field, S. Lindley, T. Williams, A. Todgham, N. Fangue, C. Jeffres, H. Bell, D. Cocherell, J. Rinchard, D. Tillitt, B. Finney, D. Honeyfield, T. Lipscomb, S. Foott, K. Kwak, M. Adkison, B. Kormos, S. Litvin, and I. Ruiz-Cooley.  2021.  Mechanisms, impacts, and mitigation for thiamine deficiency and early life stage mortality in California’s Central Valley Chinook salmon.  N. Pac. Anadr. Fish Comm. Tech. Rep. 17: 92–93.  https://doi.org/10.23849/npafctr17/92.93.