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Abstract

Photoperiod manipulation is a widely used technique in commercial aquaculture to
influence endogenous rhythms in fish, which enables industry to control events such as
reproductive timing, maturation and growth. The ability to use photoperiod manipulation
to influence these events has benefited commercial industry by improving production of
fish, thereby generating increased economic benefits. The majority of photoperiod
manipulation research has being applied to temperate species, whereas recently these
techniques have also been successful in sub-tropical and tropical species. Photoperiod
manipulation research on barramundi has demonstrated conflicting results, and
clarification is required as to whether using extended day length is effective in enhancing
growth of juvenile barramundi. This thesis confirms photoperiod manipulation to be
effective at enhancing growth of juvenile barramundi. In the majority of experiments,
continuous light (24L:0D) significantly increased wet weight, total length and SGR
weight and length of juvenile barramundi when compared to rearing fish under 12L:12D.
In addition, growth increases observed in fish reared under 24L:0D occurred without
significant increases in feed intake, demonstrating higher feed conversion efficiencies
compared to fish reared under 12L:12D.
As the Australian barramundi industry currently only uses photoperiod manipulation to
manipulate spawning events, this research enables commercial farmers to use this
technique to improve growth as well. To confirm photoperiod manipulation techniques
were applicable and effective in commercial conditions, a commercial scale experiment
was undertaken, with juvenile barramundi demonstrating significant increases in growth
when reared under 24L:0D supplied by artificial lighting.

Item Type:	Thesis - PhD
Authors/Creators:	Perks, KL
Keywords:	Barramundi, growth, endocrine, photoperiod, aquaculture
Additional Information:	Copyright the Author
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