Endocrine Control of Salmonid Development and Seawater Adaption

This project seeks to reduce losses of fish due to improper timing of release from hatcheries by developing an accurate physiological assessment of salmon development and the endocrine mechanisms responsible for this development. Heretofore the general period for hatchery release has been decided according to the regular (Gregorian) calendar, and based on insufficient biological information. As a consequence, the actual date of hatchery release or transport for subsequent release was determined by river conditions (which in part corresponded to water releases from dams), transport facilities, hatchery logistics, and other special considerations having little to do with factors determining ultimate contribution to the salmon fishery. We plan to investigate the relation between the lunar cycle-based thyroxin surge and the several components of smoltification and to establish a reliable endocrinology of development and seawater adaptation by continuing our analysis of a variety of endocrine mechanisms.