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Koura farmers need A VOICEVOIC oura farmers need BY NEIL DE JONG F arming koura, or freshwater crayfi sh, is considered a niche industry in New Zealand. It has been established for over 20 years. In the mid-1970s, koura was identifi ed as a potential species for export markets in France and Sweden. The onset of the crayfi sh plague Amphanomyces astaci, a water mould, decimated European stocks from the turn of the century into the late-1980s. These circumstances established a potential demand for New Zealand koura, since European crayfi sh stocks would exceed supply. It was estimated that export-quality crayfi sh would fetch $20 per kilo on the open market, based on prices of the European noble crayfi sh Astacus astacus. The research division of the Ministry of Fisheries studied breeding and growing koura in Te Kaha, Bay of Plenty, with Dr Jones in the 1970s. Additional feasibility studies were also conducted to explore the economics of koura farming. The results were disappointing. Jones estimated farms would have to be 6ha in size for koura farming to be economically viable as a primary income, with animals being 90-100mm long (30-35g) and stocking densities of around 80 koura/m2 . However, Jones only managed to achieve stocking densities of 16 koura/m2 . While the outcome of these studies was not positive for the future of the industry, this did not deter many from attempting, and succeeding in some cases, cultivation to provide sustainable profi t margins. Despite initial advances in New Zealand koura farming, little is known about its present status. The lack of an integrated governing body means there are few mechanisms or controls that would allow for analysis of the status of this freshwater fi shery. While farmers are currently employing innovative and experimental initiatives for improving production practices, many questions remain. • What is the best practice for rearing koura INTERESTING FACTS ABOUT KOURA Two species of koura are commonly farmed, Paranephrops planifrons and Paranephrops zealandicus, or northern koura and southern koura respectively. The distribution of koura is allopathic, meaning there has been no interbreeding due to geographical barriers, namely the Southern Alps. Northern koura grow to 70mm and southern koura to 90mm in the wild. There are four to fi ve age classes. Adults only become sexually mature in their second year. Females are able to breed when they reach 20mm carapace length, and seem to only breed for two consecutive years. Koura have a long association with Maori, who have utilised them as a food source. No evidence exists of Maori historically farming koura, but they developed sophisticated methods to harvest wild koura and in some cases to transfer koura between streams. Some of these methods are still used in surveys. There is even mention of wars having broken out over access rights to the right type of ferns to trap koura. The Treaty of Waitangi has not completed claims relating to freshwater taonga (treasures). • What are the average stocking densities being maintained • What is New Zealand's annual production • Is koura farming profi table and is it economically viable, and • Currently, is there a signifi cant local and international demand? To investigate and establish a base line for the New Zealand koura farming industry, Auckland University of Technology (AUT), Bay of Plenty Polytechnic (BOPP) and AQUA™ developed a postal survey. The Ministry of Fisheries supplied a register of all licensed koura farmers. All farmers were invited to participate in the survey, which encompassed the style of aquaculture farming (intensive to extensive), pond sizes, stocking densities, survival rates, water quality, customer base, wholesale price and farmers' perceptions for the future of the industry. Of the 17 licensed farms, 10 farmers responded. A number were actively trading but only one listed koura farming as a primary income. Three farmers were researching best practices, one was building stock numbers and three were not farming at all. Acquiring broodstock is accomplished under a special permit from MFish and in consultation with the Department of Conservation. DoC is mindful that should koura become commercially viable, wild stocks could be at risk through unlicensed or sanctioned harvesting. Six of the 10 registered farmers had breeding programmes to enhance koura characteristics (eg. tail meat, colour and size) and provide broodstock. This was especially encouraging, since it reduces unnecessary pressure on wild stock, satisfying conservation concerns. In addition, farmers often trade animals to provide broodstock, thereby further reducing the need to acquire wild koura. Respondents employed a range of aquaculture practices from extensive to intensive cultivation. Most, however, utilised semi-intensive farming, with the average farm being 1.2ha. The mean stocking densities of northern koura were 30.3 koura/m2 (n=4). There were not enough respondents to determine a mean stocking density for southern koura. The survival rate for northern koura was found to be almost 89 percent ( n=3). On average, koura is sold for $63.75 per kilo (n=5). However, prices can be considerably better when dealing in the aquarium trade. The mean total production of koura in New Zealand is 1.2 tonnes per annum. Currently there is no standardised grading system of weight and sizes used in koura sales to establish market awareness of good quality characteristics. Farmed northern koura were sold at 50mm and farmed southern koura at 150mm. The selling weight was 52.5g for northern koura and 55g for southern koura. As with any aquaculture venture, good water quality was imperative. Concerns were raised in the survey about environmental pollution from agriculture farming potentially causing the farms to have to close. As part of this study, the author contacted a number of regional councils and found most were willing to discuss freshwater aquaculture farming, should there be a demand for it. However, none of those contacted had thus far developed specifi c aquaculture polices. Koura are not considered a high-profi le species and 14 ■ NZ AQUACULTURE ■ SEPTEMBER/OCTOBER 2011