Meeting Abstract

63.1  Saturday, Jan. 5  Downstream: the hormonal control of smolt development in salmon. MCCORMICK, S.D.; USGS. Conte Anadromous Fish Res Ctr mccormick@umext.umass.edu

The parr-smolt transformation is a series of behavioral, morphological and physiological changes that are adaptive for downstream migration and seawater entry. The Bern lab conducted some of the earliest work on the hormonal control of smolting, particularly with regard to the development of seawater tolerance. Growth hormone, insulin-like growth factor I, cortisol and thyroid hormones increase during smolt development, whereas prolactin decreases. There are important interactions among these endocrine axes that control the timing and magnitude of smolt development. The recent identification of salinity-specific isoforms of the ion transporting enzyme Na/K-ATPase has helped identify cellular changes in the gill that promote salt secretory capacity and their hormonal control. Areas of future research include the hypothalamic control of smolting and the identity of mechanisms contributing to interaction of endocrine axes during this “pan-hyperendocrine” developmental event.