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Migration tendency in juvenile steelhead trout, Salmo gairdneri Richardson, injected with thyroxine and thiourea
Author(s) -
Birks E. K.,
Ewing R. D.,
Hemmingsen A. R.
Publication year - 1985
Publication title -
journal of fish biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.672
H-Index - 115
eISSN - 1095-8649
pISSN - 0022-1112
DOI - 10.1111/j.1095-8649.1985.tb04268.x
Subject(s) - thiourea , salmo , juvenile , biology , endocrinology , saline , medicine , hormone , trout , fishery , fish <actinopterygii> , chemistry , ecology , organic chemistry
Juvenile steelhead trout, Salmo gairdneri injected with thyroxine (T 4 ) near the time of seaward migration exhibited a significantly lower migration tendency than untreated controls of fish injected with saline, thiourea, or a combination of T 4 and thiourea. Fish injected with thiourea alone or in combination with T 4 prior to the time of maximum migration tendency showed enhanced migration over untreated and saline injected controls and those injected with T 4 alone. Injections of T 4 or a combination of T 4 and thiourea elevated plasma T 4 and tri‐iodothyronine (T 3 ) concentrations, while injection of thiourea alone depressed thyroid hormone levels relative to saline‐injected controls. Plasma concentrations of T 3 and T 4 returned to control levels within 10 days in all groups. We suggest that thyroid hormones are antagonistic to mechanisms underlying seaward migration of steelhead trout and that these antagonistic effects must be overcome before migration tendency is expressed.