Optimising the transport of Crassostrea gigas for aquaculture.
Transporting oysters in air between growing sites is common practice in the New Zealand Pacific oyster (Crassostrea gigas) aquaculture industry. However, this process is detrimental to their post-transport survival, leading to significant stock losses. Additionally, the New Zealand oyster industry d...
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| Format: | Other/Unknown Material |
| Language: | English |
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University of Canterbury
2020
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| Online Access: | https://hdl.handle.net/10092/101156 https://doi.org/10.26021/10220 |
| Summary: | Transporting oysters in air between growing sites is common practice in the New Zealand Pacific oyster (Crassostrea gigas) aquaculture industry. However, this process is detrimental to their post-transport survival, leading to significant stock losses. Additionally, the New Zealand oyster industry does not currently have techniques to quickly and accurately assess levels of physiological stress to allow for better decision- making (i.e. delaying transport or avoiding additional handling) in the production process. This work focused on two areas: (1) finding ways to improve post-transport survival, and (2) investigating straightforward techniques that could be used to assess stress levels of oysters in the field. Effects of handling and husbandry methods before, during and after transport on oyster post-transport survival and condition, as well as six different techniques for determining stress (biomarkers) were investigated. Two techniques (periodic air exposure and variations in stocking density) were investigated in an attempt to condition or "harden" oysters in the three weeks prior to transport. Oysters were subjected to either no air exposure (oysters continuously submerged), or air exposure periods of up to 69% of the week for the duration of either 1, 2 or 3 weeks. There were also two stocking densities used (6 litres and 13 litres of oysters per 37 litre mesh bag). Air exposure did not result in better post-transport survival. Lower stocking density resulted in a better condition index (ratio of meat to shell volume), suggesting that oysters stocked at a lower density were in a better condition to survive transport. Temperature and humidity in transit between growing sites were investigated to determine the optimal conditions for post-transport survival. Combinations of two temperatures (6°C and 12°C) and two relative humidity (RH) levels (low - 55% and high - 90% RH) were assessed. Conditions of 6°C and 90% RH imposed the least amount of stress on oysters and therefore were the most favourable for ... |
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