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 transport. On arrival at the destination farms, the return of oysters to the water is frequently delayed due to inaccessibility of the intertidal farm space at low tide. The effects of those delays on oysters were investigated. Delays of 2, 8, 22 and 46 hours were simulated and the highest survival rate was observed when oysters were returned to the water within 2 hours, followed by a two-fold decrease in survival after 8 and 22 hours. A delay of 46 hours decreased the survival eight-fold compared with the 2-hour delay. Growth and stress levels were also negatively affected by the delays. Throughout the study, the effects of various treatments on oyster stress levels were assessed with six different techniques: haemocyte counts, haemolymph pH, haemolymph refractive index and osmolality, weight loss in air and algae clearance rate. Haemolymph refractive index was the most reliable and accurate indicator of stress in this study, showing an increase in haemolymph density in response to stressors such as temperature, air exposure and grading. Its ease-of-use also makes it a promising candidate for measurements of shellfish stress in the field. A range of improvements to the current oyster transport methods are recommended, including avoiding high stocking densities prior to transport, keeping the transport temperature at 6°C and maintaining conditions of high humidity and expediting the return of oysters to the water upon arrival at the destination sites.