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Annual change in reproductive condition and plasma concentrations of sex steroids in black bream, Acanthopagrus butcheri (Munnro) (Sparidae)

journal contribution
posted on 2023-05-16, 11:12 authored by James Haddy, Pankhurst, NW
Changes in gonadosomatic index (GSI), hepatosomatic index (HSI), gonad stage and plasma concentrations of sex steroids were studied over one year in black bream (Acanthopagrus butcheri). Black bream have an annual reproductive cycle with a 3-month spawning season in spring-early summer. GSI and HSI values were highest in October and May respectively. Plasma concentrations of oestradiol-17β (E2), testosterone (T) and 17,20β-dihydroxy-4-pregnen-3-one (17,20βP) were highest in females in October. Plasma concentrations of E2 and T were highest in ovulated fish. Concentrations of 17,20βP were higher in fish undergoing final oocyte maturation (FOM) than in fish with regressed gonads. In males, plasma concentrations oft and 11-ketotestosterone (11KT) increased in September and remained elevated until January, but concentrations of 17,20βP did not change with season. However, 17,20βP concentrations in spermiated fish were higher than in nonspermiated fish. Daily changes in gonad condition indicated that females undergo daily cycles of ovarian maturation with ovulation occurring after midday. Plasma T and 17,20βP concentrations of females were elevated at midday in association with FOM, but E2 showed no diel change. In males, partially spermiated fish were dominant in the early morning and fully spermiated fish at midday. Plasma T, 11KT and 17,20βP concentrations were low at midnight and reached maximum levels at 0600 hours.

History

Publication title

Marine and Freshwater Research

Volume

49

Issue

5

Pagination

389-397

ISSN

1323-1650

Department/School

Institute for Marine and Antarctic Studies

Publisher

CSIRO

Place of publication

Melbourne

Repository Status

  • Restricted

Socio-economic Objectives

Expanding knowledge in the environmental sciences

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