Physiological and molecular endocrine changes in maturing wild sockeye salmon, Oncorhynchus nerka, during ocean and river migration
{feed: pubDate}

Abstract Maturing adult sockeye salmon Oncorhynchus nerka were intercepted while migrating in the ocean and upstream in freshwater over a combined distance of more than 1,300 km to determine physiological and endocrine changes associated with ionoregulation. Sockeye migrating through seawater and freshwater showed consistent declines in gill Na+/K+-ATPase (NKA) activity, plasma osmolality and plasma chloride concentration. In contrast, plasma sodium concentration became elevated in seawater as fish approached the river mouth and was then restored after sockeye entered the river. Accompanying the movement from seawater to freshwater was a significant increase in mRNA for the NKA ?1a subunit in the gill, with little change in the ?1b subunit. Potential endocrine signals stimulating the physiological changes during migration were assessed by measuring plasma cortisol and prolactin (Prl) concentrations and quantifying mRNA extracted from the gill for glucocorticoid receptors 1 and 2 (GR1 and GR2), mineralocorticoid receptor (MR), growth hormone 1 receptor (GH1R), and prolactin receptor (PrlR). Plasma cortisol and prolactin concentrations were high in seawater suggesting a preparatory endocrine signal before freshwater entry. Generally, the mRNA expression for GR1, GR2 and MR declined during migration, most notably after fish entered freshwater. In contrast, PrlR mRNA increased throughout migration, particularly as sockeye approached the spawning grounds. A highly significant association existed between gill PrlR mRNA and gill NKA ?1a mRNA. GH1R mRNA also increased significantly, but only after sockeye had migrated beyond tidal influence in the river and then again just before the fish reached the spawning grounds. These findings suggest that cortisol and prolactin stimulate ionoregulation in the gill as sockeye salmon adapt to freshwater.




  • Content Type Journal Article
  • Pages 1-14
  • DOI 10.1007/s00360-011-0600-4
  • Authors
    • A.-M. Flores, Ecosystem Science and Management (Biology) Program, University of Northern British Columbia, Prince George, BC V2N 4Z9, Canada
    • J. M. Shrimpton, Ecosystem Science and Management (Biology) Program, University of Northern British Columbia, Prince George, BC V2N 4Z9, Canada
    • D. A. Patterson, Fisheries and Oceans Canada, Cooperative Resource Management Institute, Simon Fraser University, Burnaby, BC V5A 1S6, Canada
    • J. A. Hills, Fisheries and Oceans Canada, Cooperative Resource Management Institute, Simon Fraser University, Burnaby, BC V5A 1S6, Canada
    • S. J. Cooke, Fish Ecology and Conservation Physiology Laboratory, Department of Biology and Institute of Environmental Science, Carleton University, Ottawa, ON K1S 5B6, Canada
    • T. Yada, National Research Institute of Fisheries Science, Fisheries Research Agency, Nikko, Tochigi 321-1661, Japan
    • S. Moriyama, School of Fisheries Sciences, Kitasato University, Sanriku, Iwate 022-0101, Japan
    • S. G. Hinch, Centre for Applied Conservation Research, Department of Forest Sciences, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
    • A. P. Farrell, Department of Zoology and Faculty of Agricultural Sciences, University of British Columbia, Vancouver, BC V6T 1Z4, Canada





More...