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dc.contributor.authorCoward, Kevinen_UK
dc.contributor.authorLittle, David Cen_UK
dc.contributor.authorBromage, Niall Ren_UK
dc.description.abstractSubstrate-spawning Tilapia zillii failed to spawn in crowded holding tanks but exhibited a marked tendency to spawn soon after transfer to individually partitioned aquaria. Confined conditions suppressed the levels of serum 17β-oestradiol (E2) and testosterone (T) in females, which remained low throughout the period of confinement. Levels of both steroids rose significantly following transfer of fish to individual aquaria and were maintained at consistently higher levels than those of fish which remained confined. Proportions of stage 3 (late perinucleolar) oocytes were significantly lower (P less than 0.001) in individual fish 21–30 days after transfer, coincident with significantly higher (P less than 0.01) proportions of stage 6 or 7 oocytes (late vitellogenic or maturing oocytes). However, no significant differences (P≥0.05) were detected between individual or confined groups of fish in the relative proportions of stage 2 (early perinucleolar), stage 4 (cortical alveolar) or stage 5 (early vitellogenic) oocytes. Atresia increased as the period of confinement increased. Following return of individual fish to confined conditions, blood steroids fell rapidly to levels seen in fish that had remained confined throughout. It is suggested that the reduced sex steroid levels detected during confinement were insufficient to allow developing oocytes to complete oocyte growth and maturation. The detection of significantly lower proportions of stage 3 and significantly higher proportions of stage 6/7 oocytes soon after transfer suggest that fish were preparing one batch of oocytes for spawning (stage 6/7 oocytes) whilst recruiting from a pool of previtellogenic oocytes (stage 3) for the ensuing spawning cycle.en_UK
dc.relationCoward K, Little DC & Bromage NR (1998) Inhibition of spawning and associated suppression of sex steroid levels during confinement in the substrate-spawning Tilapia zillii. Journal of Fish Biology, 52 (1), pp. 152-165.
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.en_UK
dc.subjectTilapia zilliien_UK
dc.subjectsex steroidsen_UK
dc.subjectspawning inhibitionen_UK
dc.subjectovarian developmenten_UK
dc.titleInhibition of spawning and associated suppression of sex steroid levels during confinement in the substrate-spawning Tilapia zilliien_UK
dc.typeJournal Articleen_UK
dc.rights.embargoreason[littled_fishbiology_1998.pdf] The 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.en_UK
dc.citation.jtitleJournal of Fish Biologyen_UK
dc.type.statusVoR - Version of Recorden_UK
dc.contributor.affiliationInstitute of Aquacultureen_UK
rioxxterms.typeJournal Article/Reviewen_UK
local.rioxx.authorCoward, Kevin|en_UK
local.rioxx.authorLittle, David C|0000-0002-6095-3191en_UK
local.rioxx.authorBromage, Niall R|en_UK
local.rioxx.projectInternal Project|University of Stirling|
Appears in Collections:Aquaculture Journal Articles

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