Aquafin CRC - Atlantic Salmon Aquaculture Subprogram: environmental control of growth and early maturation in salmonids

Funded Activity Summary

1. To accurately predict maturation rates and optimize photoperiod regimes to prevent early maturation.

Ambient environmental conditions mean that the Tasmanian salmon industry will always suffer from high maturation rates due to its high water temperatures and increased light intensity. Additional artificial lighting in Tasmania has been shown to reduce maturation by up to 30%; increase growth rates significantly; and delay maturation by 8 weeks (Porter et al., unpublished). While these strategies have improved seasonal production and have been estimated to be worth $8-16 million per year (TSGA report), seasonal fluctuations in environmental conditions and fish stocks still produce variability within their effectiveness. Trials to date have highlighted the need for increased light intensities both between sites and seasons depending on the results required. Therefore further work into the use of increased light intensity and plasma melatonin production is required.

2. To better understand the timing of oocyte maturation in relation to varied environmental conditions.

a) The development of oocytes within the gonads needs to be initiated well in advance of the fish spawning. At present it is unknown precisely when this occurs and what physiological parameters are required to allow maturation to proceed. The timing of this “gating” period will be determined as this is undoubtedly the most effective time with which to apply environmental manipulations to inhibit the maturation process to continue. The “gating mechanisms” i.e. size and energetic status will be investigated to more accurately determine the timing and duration of the application of artificial lights.

b) One hormonal candidate for the transduction of information between growth and reproductive processes is insulin-like growth factor I (IGF-I). The majority of research has investigated the interactions between the GH/IGF system and maturation during the latter stages of oocyte maturation i.e. secondary oocyte growth and development. Consequently there is a paucity of information on the impact of IGF-I on the initiation of oocyte maturation and primary oocyte growth and development. Determining the role of IGF-I at this stage would assist in our understanding of the interaction between growth and reproductive processes, and thus provide additional tools to control the timing of maturation in commercial operations.

Objectives:
1. To reduce early maturation and increase growth rates using artificial photoperiod
2. To better understand the physiological and environmental mechanisms controlling sexual development in Atlantic salmon
3. To accurately determine the intensity and duration of light required to alter growth and reproductive processes in teleost fish
4. To assess the effects of seasonal variation on growth and reproduction and be able to adjust photoperiod manipulations accordingly to reduce the variability of results.
5. To develop and introduce the transfer of technology from the Tasmanian salmon industry to other sectors of South Australian aquaculture.

Funded Activity Details

Start Date: 30-09-2005

End Date: 01-07-2009

Funding Scheme: Funding Scheme not available

Funding Amount: $333,571.00

Funder: Fisheries Research and Development Corporation

Research Topics

ANZSRC Field of Research (FoR)

There are no FoR codes available for this funding activity

ANZSRC Socio-Economic Objective (SEO)

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Other Keywords

Aquaculture | Chemistry | Climate Mitigation | Ecosystem | Physiology

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