High performance aquaculture broodstock
Aquaculture, like any other type of farming, requires stocks that perform well, but many fish farmers still rely on wild-caught broodstock of unknown quality. To develop elite broodstock for the New Zealand aquaculture industry, NIWA has established selective breeding programmes for three new species: kingfish, hāpuku and pāua (abalone).
Unlike terrestrial farming, where farmers have selectively bred their best-performing animals for centuries, marine farming is a relatively new activity.
High performing selected stocks have only been established for a few of the major fish species. Most marine farmers still rely on wild-caught broodstock of unknown quality. The problem with this is there is no way of knowing whether the resulting offspring will be fast or slow-growing, or have the traits required in commercial markets.
Selective breeding offers a tried and tested means of improving stock performance. It offers the potential to increase growth performance by up to 10-20% per generation – a figure already achieved with Atlantic salmon farmed outside of New Zealand.
In 2007, we established broodstock development programmes for three new high-value aquaculture species: kingfish, hāpuku, and pāua.
Developing high-performance broodstock involves several key challenges:
- collecting sufficient wild broodstock to establish the founding populations
- ‘closing the life cycle’ from egg to spawning so that we can reliably breed from captive-reared fish to create a selected ‘domesticated’ stock and reduce reliance on wild broodstock
- manipulating mating and spawning to establish a genetically diverse base and provide a year-round supply of seed
- determining the parentage of fertilised eggs, larvae, and juveniles
- evaluating and establishing the heritability of commercially important traits
- identifying the best-performing individuals
- optimising broodstock diet to consistently produce high-quality offspring.
With considerable expertise in fish husbandry, biology, nutrition, and genetics, NIWA is well placed to develop techniques for spawning and rearing fish in captivity, and to manipulate breeding activity.
Working with AgResearch Ltd, we have developed methods to determine the parentage of offspring using microsatellite DNA markers. These markers are highly variable regions of DNA that differ among individuals. Therefore we can generate a unique microsatellite DNA profile for each parent and then compare this to the profile inherited by the offspring. Using special software it is then possible to match the DNA profiles of the offspring to their specific parents with a high degree of accuracy.
By combining the parentage analysis with data on egg, larval, and juvenile performance, we can build a picture about which parents consistently produce good-quality offspring. These parents can be targeted for production to ensure the aquaculture industry receives only the best quality stocks for farming. Commercially important traits like growth rate are often strongly heritable, so they can be successfully improved through selection.
The current programme runs until 2013. As of August 2010, we've made significant progress on the application of selective breeding, broodstock nutrition, and DNA marker technologies to generate high-performance broodstock with traits of commercial importance.
Some key achievements are summarised here.
- Closed the life cycle for kingfish, spawning from F1 kingfish over two seasons.
- Developed methods for manipulating spawning, sexing broodstock, and assessing individual parental contribution to future generations.
- Established 100 pāua, 43 hāpuku, and more than 20 kingfish family lines for further evaluation.
- Determined the heritability of growth traits in hāpuku for the first time, making the selection of faster-growing hāpuku stocks for industry possible.
- Developed models to help design the most appropriate breeding programme for each species.
- Trialled new broodstock diets, which were readily consumed.