The role of food availability in regulating reproductive development in female golden perch

At a time of the year when female golden perch Macquaria ambigua are not no rmally reproductively active, they were either fed daily to satiety (Fed), starved for 150 days (S150), or starved for 150 days then fed to satiety fo r 30 or 60 days (S150/F30 or S150/F60). Fish showed rapid growth and increa sed food conversion efficiency upon re-feeding relative to Fed animals. The hepatosomatic indices were not significantly different between Fed, S150/F 30 and S150/F60 groups, but were significantly reduced in S150 animals. The gonadosomatic indices (I,) for both Fed and S150 animals were not signific antly different. However, the I, values for S150/F30 and S150/F60 animals o f 6.74 +/- 1.22 and 7.84 +/- 1.12 were significantly elevated relative to F ed animals and approach those described for wild mature M. ambigua. Oocyte development in Fed and S150 animals did not proceed past the cortical alveo li or perinucleolar stages, respectively, but oocytes in both S150/F30 and S150/F60 animals had undergone vitellogenesis and were close to being matur e. The concentration of oestradiol and testosterone in the plasma of S150/F 30 and S150/F60 animals increased in accordance with the proposed role of t hese hormones in teleost reproductive cycles. The reproductive response of M. ambigua to starvation and re-feeding is well suited to reproductive succ ess in temperate Australian rivers where food availability is unpredictable . (C) 1999 The Fisheries Society of the British Isles.