Up to 64 families are produced in the hatchery at one time and are placed out onto commercial farms for on-growing to harvest. This has involved breeding oyster families, where one male is crossed with a female to produce a few million offspring who are all brothers and sisters. These traits include improved shell shape and meat to shell ratio.įor the past 10 Cawthron has been running a selective breeding programme for Pacific oysters with support from Pacific Marine Farms Ltd. Some selection is still made for fast growth and good survival but the priority now is for traits that increase the percentage of oysters meeting the highest paying Jemco grades. Companies exporting under Jemco have been quick to recognise the potential of selective breeding to improve product quality. The Pacific oyster industry in New Zealand already markets high value product into overseas niche markets under the Jemco brand. With the selective breeding well underway, Cawthron's attention has shifted to more challenging and commercially interesting breeding goals. These stock management options allow them to grow a uniform crop with good overall efficiency regardless of the uncontrollable environmental conditions like food availability. Farmers can adjust the stocking density, move oysters between farms or within farms, and adjust the height of the bags in the tide. They also say that single seed allows them to manipulate the crop to suit their needs and to optimise the use of our farms. The spat arrive in poly bins big enough to go into 6mm mesh baskets.įarmer feedback is that mortality has been minimal, and the oysters generally have a better shape than oysters grown on sticks. All that is required is an email message to the hatchery. Stick culture requires a lot of labour whereas this system lends itself to mechanisation.Ĭawthron supplies farmers with single seed spat. Many farmers grow oysters on sticks but over the past five to eight years some have been working to convert their farm from this traditional style to the long-line system, growing single seed oysters in a plastic basket suspended on a plastic long-line. This has been very successful, and commercial oyster lines now have growth rates more than 20% higher than the average crop from wild spat. However breeding for growth rate and yield are straightforward and it has been done successfully overseas so the first step in a Pacific oyster breeding programme at the Cawthron Institute has been to replicate the results from overseas. In many cases oysters reach harvest size in only one year and survival commonly exceeds 90%, so the economic benefits to New Zealand oyster farmers of faster growth and increased survival are not that great. Things are a little different in New Zealand. In many countries, oysters take up to 3 years to mature, and survival may be well below 50% so improvements to growth rate and survival have big economic benefits to oyster farmers. In the case of oysters, this was achieved through selecting for faster growth and increased survival. As is common with many breeding programmes, the initial priority was to increase yield. Selective breeding of the Pacific oyster was started in the USA in the 90s. Aesthetic considerations are important for an oyster buyer, and people are often prepared to pay more for an oyster that looks good and tastes even better. The other option is to add value and make the product more attractive. One option is to try and grow them cheaper but New Zealand will always be up against the costs of shipping export products into overseas markets. This is good for commodity products but what happens when you’re dealing with a delectable high value product like a Pacific oyster? And for hundreds of years, primary producers have been turning to selective breeding to help them grow more crop for less effort. Cutting production costs and increasing efficiency are two of the first things farmers do when the going gets tough.
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