Relationship between gill Na+,K+-ATPase activity and downstream movement in domesticated and first-generation offspring of wild anadromous brown trout ( Salmo trutta )

Kim Aarestrup, C. Nielsen, S.S. Madsen

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

The relationship between smolt status and downstream movement following release was investigated in two stocks of hatchery- reared anadromous brown trout (Salmo trutta). Yearlings from a domesticated stock (DS) and first-generation offspring (F1) of wild anadromous trout were held under identical conditions from August 1997 until the following spring, where they developed smolt characteristics as judged from increasing gill Na+,K+- ATPase activity. Presmolts (low Na+,K+-ATPase activity), smolts (high Na+,K+-ATPase activity), and desmolts (regressed Na+,K+- ATPase activity) were released on three occasions into the River Salten. Using both dye-marked and radiotagged fish, downstream movement was monitored by either trapping 3 km downstream (dye-marked fish) or radiotracking on a daily basis. The experiments showed a positive correlation between smolt status (gill Na+,K+-ATPase activity) and downstream movement. Gill Na+,K+-ATPase activity may therefore be used as an indicator of migratory readiness in brown trout. F1 and DS trout had the highest migration frequency when released as presmolts and smolts, respectively. Despite smaller size, F1 trout had similar or better survival than DS trout after release. Our data suggest that initiation of downstream movement is influenced by an interaction between the previous physiological development of the fish and a discrete level of water discharge or water temperature
Original languageEnglish
JournalCanadian Journal of Fisheries and Aquatic Sciences
Volume57
Issue number10
Pages (from-to)2086-2095
ISSN0706-652X
DOIs
Publication statusPublished - 2000

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