Smolt physiology and endocrinology: Chapter 5

Edited by: Stephen D. McCormickAnthony Peter Farrell, and Colin J. Brauner



The parr-smolt transformation of anadromous salmonids is a suite of behavioral, morphological, and physiological changes that are preparatory for downstream migration and seawater entry. The timing of smolt development varies among species, occurring soon after hatching in pink and chum salmon and after one to several years in Atlantic salmon. In many species the transformation is size dependent and occurs in spring, mediated through photoperiod and temperature cues. Smolt development is stimulated by several hormones including growth hormone, insulin-like growth factor-1, cortisol, and thyroid hormones, whereas prolactin is generally inhibitory. Increased salinity tolerance is one of the most important and tractable changes, and is caused by alteration in the function of the major osmoregulatory organs, the gill, gut, and kidney. Increased abundance of specific ion transporters (Na+/K+-ATPase, Na+/K+/Cl− cotransporter and apical Cl− channel) in gill ionocytes results in increased salt secretory capacity, increased growth and swimming performance in seawater, and higher marine survival.
Publication type Book chapter
Publication Subtype Book Chapter
Title Smolt physiology and endocrinology: Chapter 5
ISBN 9780123969514
DOI 10.1016/B978-0-12-396951-4.00005-0
Volume 32
Year Published 2012
Language English
Publisher Elsevier
Contributing office(s) Leetown Science Center
Description 53 p.
Larger Work Type Book
Larger Work Subtype Other Government Series
Larger Work Title Euryhaline Fishes
First page 199
Last page 251
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