THE USE OF PHOTOPERIOD IN THE PRODUCTION OF OUT-OF-SEASON ATLANTIC SALMON (SALMO-SALAR) SMOLTS

Citation
Ma. Thrush et al., THE USE OF PHOTOPERIOD IN THE PRODUCTION OF OUT-OF-SEASON ATLANTIC SALMON (SALMO-SALAR) SMOLTS, Aquaculture, 121(1-3), 1994, pp. 29-44
Citations number
32
Categorie Soggetti
Fisheries,"Marine & Freshwater Biology
Journal title
ISSN journal
00448486
Volume
121
Issue
1-3
Year of publication
1994
Pages
29 - 44
Database
ISI
SICI code
0044-8486(1994)121:1-3<29:TUOPIT>2.0.ZU;2-P
Abstract
Accelerated seasonally-changing and ''square-wave'' (direct change fro m short to long day) photoperiods advanced the timing of potential S1 (1+) and S2 (2+) smolts by a maximum of 3 and 7 months respectively. P re-smolts underwent body silvering, fin darkening and a decrease in co ndition factor in response to changes from short to long day-lengths. Seawater challenge (24 h, 28 ppt) tests showed these fish to develop s trong hypo-osmoregulatory ability. Smolts were transferred to full str ength seawater in small land-based facilities and to commercial on-gro wing sites. S1 groups, which were advanced by up to 3 months, gained a growth advantage from early seawater transfer that was maintained thr oughout their first year in seawater. Potential S2 smolts transferred in October-November grew well over their first winter. Advanced mixed sex S1s did not show any post-smolt maturation, but did show increased rates of maturation (up to 19%) after one winter at sea. Advanced S2 smolts showed an increased post-smolt maturation.