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dc.contributor.authorTaylor, John-
dc.contributor.authorPorter, Mark J R-
dc.contributor.authorBromage, Niall R-
dc.contributor.authorMigaud, Herve-
dc.description.abstractSize reflecting growth rate, energy balance or nutritional status is regarded as an important determinant of the ability of trout to undergo puberty. The relationship of a change in photoperiod, either natural (SNP) or advancing (ADV), with growth, IGF-I and reproduction was investigated in virgin female rainbow trout. Under SNP 63% of the population attained maturity while only 29% spawned 6 months in advance in the ADV regime. Under SNP both size and growth rate in late spring-early summer appeared to determine whether an individual may initiate reproduction while condition factor appeared to be a better predictor in the ADV regime. A complete seasonal relationship between plasma IGF-I, daylength and temperature was demonstrated under natural conditions, and provides direct evidence for the relationship between reproduction and IGF-I. Conversely, trout maintained under ADV exhibited a significantly different plasma IGF-I profile relative to those under a natural photoperiod. Furthermore, IGF-I levels accurately reflected growth rate prior to elevations in sex steroids, suggesting that IGF-I may provide an endocrine signal between the somatotropic and reproductive axes that growth rate and/or size is sufficient to initiate gonad development. In addition, maturing individuals under SNP typically expressed higher circulating IGF-I levels than those that remained immature and may reflect a greater opportunity for IGF-I to act on the pituitary to stimulate gonadotropin production. We observed elevated levels in maturing fish for 3 months under SNP compared to only I month under ADV were observed. This may reflect a reduction in the window of opportunity to initiate reproduction under advancing photoperiods and hence explain the reduction in fish successfully recruited.en_UK
dc.relationTaylor J, Porter MJR, Bromage NR & Migaud H (2008) Relationships between environmental changes, maturity, growth rate and plasma insulin-like growth factor-I (IGF-I) in female rainbow trout, General and Comparative Endocrinology, 155 (2), pp. 257-270.-
dc.rightsThe publisher does not allow this work to be made publicly available in this Repository. Please use the Request a Copy feature at the foot of the Repository record to request a copy directly from the author. You can only request a copy if you wish to use this work for your own research or private study.-
dc.subjectOncorhynchus mykissen_UK
dc.titleRelationships between environmental changes, maturity, growth rate and plasma insulin-like growth factor-I (IGF-I) in female rainbow trouten_UK
dc.typeJournal Articleen_UK
dc.rights.embargoreasonThe publisher does not allow this work to be made publicly available in this Repository therefore there is an embargo on the full text of the work.-
dc.citation.jtitleGeneral and Comparative Endocrinology-
dc.type.statusPublisher version (final published refereed version)-
dc.publisher.addressSAN DIEGO, CA-
dc.contributor.affiliationRidley Corporation-
dc.contributor.affiliationUniversity of Stirling-
Appears in Collections:Aquaculture Journal Articles

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