Simulated maternal stress reduces offspring aerobic swimming performance in Pacific salmon

Amanda I Banet; Stephen J Healy; Erika J Eliason; Edward A Roualdes; David A Patterson; Scott G Hinch

doi:10.1093/conphys/coz095

Simulated maternal stress reduces offspring aerobic swimming performance in Pacific salmon

Conserv Physiol. 2019 Dec 18;7(1):coz095. doi: 10.1093/conphys/coz095. eCollection 2019.

Authors

Amanda I Banet^{1

2}, Stephen J Healy², Erika J Eliason^{2

3}, Edward A Roualdes⁴, David A Patterson⁵, Scott G Hinch²

Affiliations

¹ Department of Biological Sciences, California State University, Chico, 400 W. First Street, Chico, CA 95929, USA.
² Pacific Salmon Ecology and Conservation Laboratory, Department of Forest and Conservation Sciences, University of British Columbia, 2424 Main Mall, Vancouver, BC, V6T 1Z4, Canada.
³ Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, Santa Barbara, CA 93106, USA.
⁴ Department of Mathematics and Statistics, California State University, Chico, 400 W. First Street, Chico, CA 95929, USA.
⁵ Fisheries and Oceans Canada, Science Branch, Pacific Region, Co-operative Resource Management Institute, School of Resource Environmental Management, Simon Fraser University, 8888 University Drive, Burnaby, BC, V5A 1S6, Canada.

Abstract

Pacific salmon routinely encounter stressors during their upriver spawning migration, which have the potential to influence offspring through hormonally-mediated maternal effects. To disentangle genetic vs. hormonal effects on offspring swimming performance, we collected gametes from three species of Pacific salmon (Chinook, pink and sockeye) at the end of migration and exposed a subset of eggs from each female to cortisol baths to simulate high levels of maternal stress. Fertilised eggs were reared to fry and put through a series of aerobic swim trials. Results show that exposure to cortisol early in development reduces maximum oxygen consumption while swimming, and decreases aerobic scope in all three species. Resting oxygen consumption did not differ between cortisol and control treatment groups. We also examined several metrics that could influence aerobic performance, and found no differences between treatment groups in haematocrit%, haemoglobin concentration, heart mass, citrate synthase activity or lactate dehydrogenase activity. Though it was not the focus of this study, an interesting discovery was that pink salmon had a higher MO_2max and aerobic scope relative to the other species, which was supported by a greater haematocrit, haemoglobin, a larger heart and higher CS activity. Some management and conservation practices for Pacific salmon focus efforts primarily on facilitating adult spawning. However, if deleterious effects of maternal stress acquired prior to spawning persist into the next generation, consideration will need to be given to sub-lethal effects that could be imparted onto offspring from maternal stress.

Keywords: Oncorhynchus; Pacific salmon; cortisol; maternal effects; respirometry; swimming performance.