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Induced ovulation and larval rearing of four species of Australian marine fish

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Battaglene, S. C (1995) Induced ovulation and larval rearing of four species of Australian marine fish. PhD thesis, University of Tasmania.

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Abstract

This thesis developed techniques for the large-scale breeding of marine fish in New South
Wales. It provides the first published account of the hormone induction and larval rearing to
metamorphosis of Australian bass Macquarie novemaculeata (Percichthyidae), snapper
Pagrus auratus (Sparidae), mulloway Argyrosomus hololepidotus (Sciaenidae) and sand
whiting Sillago ciliate (Silliganidae) in Australia. Wild-caught broodstock were induced to
spawn using hormones (hCG, LHRHa, Ovaprim) and either spawned naturally or were
stripped. Pagrus auratus and S. ciliate were found to be multiple spawners with asynchronous
ovaries. Conversely, M. novemaculeata and A. hololepidotus were found to be highly fecund
single spawners having group synchronous ovaries. All four species were successfully
induced to ovulate after periods in captivity ranging from one to five years. Species specific
differences in hormone induction were determined, particularly in relation to the overripening
of eggs and the optimum time between treatment and stripping.
Commercial scale batches of larvae were reared in 2000 L conical tanks and replicated
experiments were conducted in aquaria ranging in size from 2 to 70 L. Larval development for
all four species was described and egg size, time to hatch, size at hatch, yolk size, oil globule
size, and beginning of exogenous feeding were compared among species. First feeding
larvae were reared on rotifers Brachionus plicatilis and then brine shrimp Artemia sp..
Survival, growth and weaning of larvae at metamorphosis were compared.
Factors affecting larval survival, particularly those influencing initial swim bladder
development were tested in replicated laboratory experiments. The timing of swim bladder
inflation was found to coincide with the start of exogenous feeding but feeding was not
required for initial swim bladder inflation. Larvae that failed to inflate their swim bladder grew
poorly and were susceptible to stress induced mortality. Light intensity, was shown to be an
important factor influencing swim bladder inflation in cultured larvae. The effect of light
intensity on inflation in M. novemaculeata and S. ciliate was quantified. Exposure to
continuous light (100-200 Lux) inhibited inflation in M. novemaculeata. In contrast, S. ciliate
were shown to have a diel pattern of nocturnal inflation and required higher light intensities to
feed (1000 Lux). Manipulative experiments with S. ciliate larvae showed that they responded
to darkness by inflating their swim bladders. Other abiotic factors such as surface access, low
salinity and high aeration were shown to reduce inflation in larvae. Initial swim bladder inflation
strategies are discussed and recommendations made regarding the importance of
maximising inflation.
The results of the study were used to assess the relative difficulty of intensive commercial
production of each species for aquaculture.

Item Type: Thesis (PhD)
Keywords: Marine fishes, Aquaculture
Copyright Holders: The Author
Copyright Information:

Copyright 1995 the Author - The University is continuing to endeavour to trace the copyright
owner(s) and in the meantime this item has been reproduced here in good faith. We
would be pleased to hear from the copyright owner(s).

Additional Information:

Thesis (Ph.D.)--University of Tasmania at Launceston, 1995. Includes bibliographical references

Date Deposited: 25 Nov 2014 00:46
Last Modified: 11 Mar 2016 05:55
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