10 abalone culture 8 allsopp2011

8 Abalone Culture Mark Allsopp, Fabiola Lafarga-De la Cruz, Roberto Flores-Aguilar and Ellie Watts 8.1 INTRODUCTION Abalone is a prized seafood delicacy worldwide Abalone are marine gastropod molluscs of the family Haliotidae, also called sea snails, ear-shells or sea ears They possess a single shell, which is a low open spiral structure, and a large muscular foot that is used to attach to hard surfaces The family Haliotidae contains one genus, Haliotis, and about 100 species are recognised worldwide (Jia & Chen 2001) More information on the biology of abalone can be found in Jia and Chen (2001) Aquaculture activities have grown considerably in the past decade, increasing their contribution to the global market as fisheries continue to decline worldwide Abalone aquaculture industry has rapidly developed from about 3,000 tons in 2000 to over 40,000 tons in 2008 (FAO 2010) The principal countries producing cultured abalone are China, Korea and Taiwan Several other countries including Australia, Chile, Mexico, New Zealand, South Africa, Thailand and the United States are also developing abalone aquaculture industries With the maturity of production lines from farms worldwide the industry has established markets in mainland China through Hong Kong, Japan and Singapore The demand for cocktail-size abalone has driven the expansion and development of the industry throughout the producer countries A variety of abalone species are cultivated around the world (see Table 8.1) 8.2 THE ABALONE MARKET The two largest consumers of wild and cultivated abalone are China and Japan Generally the Chinese prefer a lighter coloured ‘foot’ and the Japanese a darker one; a characteristic Recent Advances and New Species in Aquaculture, First Edition Edited by Ravi K Fotedar, Bruce F Phillips © 2011 Blackwell Publishing Ltd Published 2011 by Blackwell Publishing Ltd 232 Recent Advances and New Species in Aquaculture Table 8.1 Abalone species cultivated around the world Country Commonly cultivated species Australia New Zealand China and Taiwan Taiwan Korea Haliotis laevigata and Haliotis rubra Haliotis iris and Haliotis australis Haliotis discus hannai Haliotis diversicolor Haliotis discus, Haliotis discus hannai, Haliotis diversicolor, Haliotis diversicolor supertexta Haliotis discus hannai Haliotis asinina Haliotis midae Haliotis discus hannai, Haliotis rufescens Haliotis rufescens, Haliotis fulgens, Haliotis corrugata Haliotis rufescens, Haliotis fulgens, Haliotis corrugata Haliotis kamtschatkana Haliotis tuberculata Japan Thailand South Africa and Namibia Chile Mexico USA Canada Ireland Production 2008* (tons) 504 33,010 348 5,146 NA 30 1,040 515 60 175 NA NA Note: NA = No data available * Production data obtained from FAO Fisheries and Aquaculture Information and Statistics Service website that varies between species The preferred size category is between 200 and 300 g per abalone, but most cultivated abalone are sold at between 50 and 150 g 8.2.1 Japan Japan is the largest world consumer of live, fresh and frozen abalone These product forms are generally identified as having the highest premium on the world market Because Japan is the largest consumer of premium-quality abalone, Japanese consumer preferences are important in understanding the premium abalone markets The Japanese native fishery is historically significant and highly valued as a cultural resource It has given rise to cultural traditions and consumer tastes that make the appearance of an abalone as important as taste and texture when determining the value of the product (Oakes & Ponte 1996) 8.2.2 Mainland China Mainland China is the largest consumer of abalone, a fact that often remains unrecognised because consumption of abalone in China is almost entirely in the canned form In regions such as Japan and the USA, canned abalone is generally not considered a premium product Canned abalone has a traditional place in Chinese society as an item of prestige, often presented as a show of affluence or a demonstration of respect Considered customary in banquets and traditional feasts, a single can of abalone is often given as a token of respect The strong traditions surrounding abalone consumption in China have created a stratified market, based on perceived quality differences between popular brand names and countries of origin The major distribution point for canned abalone destined for mainland China is through Hong Kong (Oakes & Ponte 1996) Abalone Culture 8.2.3 233 USA In the USA there is a traditional market for abalone, which is mainly in California, where there was a flourishing fishery until the early 1970s In the California market tradition, abalone are removed from the shell and sliced into steaks, which are tenderised and then fried At one time in California, abalone was an abundant, low-cost regional delicacy, but as the fishery dwindled due to over-harvest, constricting supplies caused the market price to increase to a level that has severely restricted demand for the product The traditional US market now consists primarily of expensive, white tablecloth restaurants in California The emergence of Asian communities as a significant abalone market in major US metropolitan areas has spurred the demand for specialty food products This has kindled a demand for Asian-style abalone products in the US market The market niche is mainly for fresh abalone meat used in Japanese sushi, but a brisk market for live cultured abalone has developed in recent years (Oakes & Ponte 1996) 8.2.4 Southeast Asia Lucrative markets exist for live abalone in Hong Kong, Taiwan, Singapore, Thailand and other Asian metropolitan centres The Hong Kong market is the largest and best established of the Asian markets As well as acting as the gateway to China, Hong Kong offers a direct market for premium abalone products in many forms Product demand throughout Southeast Asia is based on established markets, which are similar to those in Hong Kong As Asian affluence increases, these market areas will become a more important market factor The combined influence of China and Southeast Asia will be significant in determining the location and product concepts best suited for future production sites (Oakes & Ponte 1996) 8.2.5 Europe Although Europe is not a major market area for cultured or fishery-caught abalone, there is a regional demand arising from the traditional fishery for H tuberculuta This market is concentrated in France, but there is some demand throughout the UK and the rest of Europe This demand is generally under-supplied and could be developed if supplies were available The European abalone species are small and traditional product presentations are well suited to the smaller (100 g) abalone produced by culturists Therefore, this region is of great interest for future market expansion 8.3 ABALONE PRODUCTION TECHNOLOGY Though culture of abalone has developed in several countries, this section focuses on developments in South America, Australia and New Zealand 8.3.1 Chile In Chile, aquaculture is an important income source for the economy It produced nearly 853,000 tons with a value of US$5.3 billion by 2007, positioning Chile among the top ten 234 Recent Advances and New Species in Aquaculture world aquaculture producers (FAO 2009) Among the aquaculture resources exploited in Chile, abalone was introduced in the late 1970s as a means of diversification, taking into consideration its high commercial value and an unsatisfied demand worldwide (FloresAguilar et al 2007) Currently, the abalone industry is supported by two foreign species: Haliotis rufescens, red abalone from California and Japanese or ezo abalone, Haliotis discus hannai from Japan Red abalone was first introduced in 1977, for experimentation in closed systems by Fundación Chile and Universidad Católica del Norte (UCN) (Godoy et al 1992) Later, in 1982, UCN introduced and adapted the culture technology of the Japanese abalone in collaboration with the Japan International Cooperation Agency (JICA) However, abalone culture technology transfer began only in 1992, when red abalone culture was authorised, in the sea off Chiloé Island in southern Chile, for a subsidiary company of Fundación Chile Japanese abalone commercial culture started in 1996 in northern Chile where several companies adapted the technology for land-based culture, as abalone seed were provided by the UCN’s Center of Abalone Production The first official red (1 ton) and Japanese abalone (8 tons) production were registered by the Undersecretary of Fisheries of Chile, in 1998 and 2003 respectively Exports began in 1999 with 36 tons of red abalone Currently, there are 19 farms in operation (11 in the north and eight in the south) Seed production is mainly in the northern region, while most growout systems are land-based in the north and in-water in the south of Chile Since 2002, Chilean legislation has allowed both species to be cultured in land-based semi-closed systems, while red abalone may also be cultured in water-suspended systems between Seno del Reloncavi and Skyring Peninsula in southern Chile (Resolution 30 September 2002) On the other hand, since 2004 the culture of both species has been permitted in the sea but only in two of the three actual culture regions located in northern Chile, and the stock has to be single-sex individuals and sited over a soft substrate area (Subpesca 2006) Currently, Chile is positioned as the fifth abalone producer worldwide with a production volume of 479 tons and an estimated value of US$11.5 million Red abalone production accounts for 97.5% of total production, as this species has been well adapted to full-cycle culture in northern and southern Chile (Enríquez & Villagrán 2008) On the other hand, Japanese abalone has not adapted well because of its minor resistance to the Chilean culture conditions (i.e water temperature and type of macroalgae availability) and is actually considered as an emergent species (less than tons a year) Unfortunately, no other abalone species have been introduced, because Chilean legislation allows only these two species to be imported and cultured, and efforts to introduce new exotic species (not endemic) had been laborious, time consuming and unsuccessful However, research on hybridisation between red and Japanese abalone has proved to be potentially important to diversify and to improve the Chilean abalone industry Moreover, abalone farming can be considered a young industry, with 70% of the farms just starting the phase of commercialisation and exportation 8.3.1.1 Conditioning and spawning induction Abalone culture technology in Chile is fully integrated in the northern region, where hatchery, nursery and growout operations are undertaken by most of the farms Only two of all the southern farms possess all culture phases, and the rest are only in-water growout facilities that are provided with red abalone seeds in the range of sizes of 15–25 mm by northern Abalone Culture 235 farms Hatchery facilities are composed of a broodstock area, a spawning area and a larval rearing system Adult abalone are maintained in a specially designed unit, separated by sexes at stocking biomasses of 25 g/L, in continuously running water at ambient temperature and normal photoperiod 12D:12L Water is usually filtered up to 25 μm, but some farms use 50 μm Acceptable water quality parameters are: water temperature 12–20 °C, pH 7.4–8.5, dissolved oxygen 7–10 mg/L, alkalinity 120–180 ppm, salinity 34–36 psu, ammonium 0.0–0.02 ppm, nitrite 0.0–0.2 ppm and nitrate 0.0–2.0 ppm Feeding rates are around 10–20% of body weight per day, supplied with a fresh mixed macroalgae diet made up mostly of Macrocystis sp (90%), Lessonia sp., red algae Gracilaria sp and green algae Ulva sp Spawning adults normally used are to years old, with a visual gonad index of 2+ to 3+ If hybridisation is desired red abalones of 2–4 years old should be used to improve fertilisation and hatching rates (unpublished data) Spawning induction is usually undergone by chemical stimulation using doses of TRIS-H2O2reactive (Morse et al 1976) in UV-irradiated water filtered at μm after hour of desiccation at ambient temperature But temperature and UV induction are also applied in some facilities, normally by raising temperature gradually up to °C at rate of °C /hour Normally, females are induced 15–30 minutes before males, but if hybridisation is undertaken males should be induced at least 15 minutes before females, to assure sperm availability as the fertilisation window for successful hybrid crosses is less than 20 minutes At increasing egg age fertilisation rates drop sharply (Lafarga-De la Cruz et al 2010) Female gametes are collected, and fertilisation is done in 20 L containers with sperm concentrations in the order of 106 sperms/mL for homospecific crosses, and 107 sperms/mL for heterospecific crosses (Lafarga-De la Cruz et al 2010), and contact times around 2–6 minutes Fertilised eggs are rinsed several times by decantation with UV-irradiated water Finally, fertilised eggs are placed forming a monolayer at the bottom of the hatching tanks (50–100 L) and left static overnight, in a controlled-temperature room (17 °C) After 16–18 hours, trocophore larvae hatch out and they are collected and selected (>150 μm) in upwelling tanks for its larval culture period of to days, depending on water temperature Antibacterial treatments are recommended daily during this period, as well as maintenance activities Normal larval development is followed daily by microscopic observations Both closed systems and flow-through systems are used for larval culture, and when the abalone larvae are competent (observation of the third tubule in cephalic tentacles, and characteristic larvae’s foot movements) they are transferred to the post-larval and juvenile tanks 8.3.1.2 Nursery technology The nursery facility for rearing abalone from post-larval to juvenile seed size (17–28 mm) is based on the Japanese plastic plate system for larval settlement (Fig 8.1) Preconditioning of plates is normally with naturally occurring diatoms, but some farms also use cultured microalgae (mainly Ulvella sp., Cocconeis spp and Navicula spp.) Abalones remain in nursery between and 10 months, depending on the type of culture system used Land-based systems use abalones of 10–15 mm in shell length into the production system, where they are maintained for 24–48 months On the other hand, in-water (non-land based) systems use slightly bigger animals (20–25 mm) for grow-out 236 Recent Advances and New Species in Aquaculture Fig 8.1 Japanese plate system for post-larval and juvenile culture 8.3.1.3 Growout technology Abalone farms in the north are characterised by land-based growout operations employing a substantial infrastructure; with many raceway tanks (Fig 8.2) and integration of all phases of production The growout tanks are 10 × 1.5 × 0.7 m, made of fibreglass, with a total volume around 11,000 L, with compartments having a conic-shaped bottom to facilitate the cleaning process They have baskets inside (1.5 × 1.5 m and 0.6 m) (Fig 8.3), made of plastic mesh (6 mm hole diameter) and plates where the abalone is attached This makes a total surface of 100 square metres available for the abalone, and the plates hold the organisms off the bottom where the waste debris from the abalone and algae is accumulated A mm thick HDPE plastic plate covers each basket and weights are added on to keep the shelters inside the water Ambient temperature seawater is used in a flow-through system The seawater exchange rate is tons per hour, and filtered seawater to 90 μm is used Air is pumped to each tank constantly The main food for growing out abalone is brown algae Three brown algal species are normally used: Lessonia trabeculata, Lessonia nigrescens and Macrocystis integrifolia, with L trabeculata being the most abundant In the north, there is a regulation that only registered companies may harvest kelp and they have to comply with scientific management regulations in order to maintain the sustainability of the resource Most of this kelp is Abalone Culture Fig 8.2 237 Raceways growout culture system (P Camanchaca Company, Caldera Chile) harvested at low tide and is cut with a knife by fishermen holding contracts with these companies The capacity of abalone per basket and shelter is constant and the number depends on the abalone size Two times a week the abalone are fed ad libitum, and the cleaning of the tank depends on the time of the year and the algal feed but is normally once a week The tank is emptied and the tank surfaces are scrubbed with a brush and then refilled with fresh seawater Most of the land-based abalone aquaculture farms in Chile monitor water quality as temperature and oxygen once a day, and salinity and phytoplankton and bacteria at least once a month In compliance with the regulations of the federal agencies (Decreto Supremo No 90/1996 Ministry of Economy), levels of suspended solids, oxygen, ammonia and temperature amongst other factors have to be continuously monitored The exact monitoring requirements and their frequency varies, however, according to the size and location of the farm and type of feed used In the south of the country, sea-based growout systems are widely used The small farmers use the barrel culture system (Fig 8.4), and only the larger production companies with inventories over million abalone use cage-based growout systems These are either plastic moulded cages or iron-galvanized structures covered with netting The cage size is normally × × m, but the most advanced cages are × × m These cages (Fig 8.5) have vertical plates as surface for the abalone to attach In these plates a maximum capacity of 65% of the total surface area of abalone is allowed 238 Recent Advances and New Species in Aquaculture Fig 8.3 Baskets with shelter plates for juvenile culture Fig 8.4 Barrel abalone growout system Abalone Culture Fig 8.5 239 Abalone growout cage with its HPDE plastic plates These containers are suspended in a typical long line, and the kelp Macrocystis pyrífera is the most widely used algal species to feed abalone To operate the culture containers the bigger farms use barges with a hoist to lift the cages The Macrocystis feed is harvested from small boats and cut with a knife On the small farms staff collect the seaweed manually, while the bigger companies pay local fishermen to supply the algae Macrocystis is abundant in summer, but almost disappears in winter, forcing farmers to purchase cultured red algae, Gracilaria chilensis While there is constant supply of cultivated Gracilaria in the south, the growers claim that Macrocystis produces much better abalone growth rates No kelp harvest permits are required in the southern regions Artificial feeds are used in some phases of the abalone growth, especially in land-based farms in the north, in both nursery and growout operations At some land-based farms, abalone of all sizes receive a combination of artificial and kelp diet No manufactured diets are used on the in-water farms because environmental regulations restrict aquaculture operations using formulated feeds As a result of the large-scale salmon culture in the region, aquaculture operations using pelleted feeds are deemed ‘intensive’ farms and sea concessions will only be granted if they are a minimum of 2.8 km from neighbouring concessions This makes it very difficult to find suitable areas for abalone culture that comply with this regulation As a result all farms in the south use seaweeds as feed One company in the north has experimented with a recirculation system for more than five years and it is proving very successful 240 Recent Advances and New Species in Aquaculture 8.3.2 Australia In 2008, abalone aquaculture emerged as one of the fastest-growing agribusiness sectors in Australia With 850 tons produced in 2006/7, worth AU$42.5 million to the Australian economy, this is estimated to grow to 1,500 tons over the next five to ten years, worth $75 million (Fleming 2008) 8.3.2.1 Conditioning and spawning technology Until recently it had been assumed that Australian abalone farmers have found it far more reliable to collect conditioned animals from the sea rather than condition them in tanks (Fleming & Roberts 2001) However, high-quality gametes can now be obtained in winter from H laevigata held in a flow-through broodstock system developed by researchers from the Western Australian Fisheries Department and industry (Freeman et al 2006) Water temperature is considered the main exogenous factor that regulates the reproductive cycle of abalone (Landau 1991; Hone et al 1999; Fleming & Roberts 2001; Maguire 2001; Plant et al 2003) Fleming and Roberts (2001) indicated that for H rubra temperatures between 15 and 17 °C are optimal In a study undertaken at Ocean Wave Seafoods farm at Lara, Victoria, Plant et al (2003) determined that H rubra can be brought into spawning condition when kept at constant temperature (18 °C) The best spawning results were achieved after 120 days, when about million eggs were spawned per female in 60% of those tested, with a 75% fertilisation rate The results clearly showed that conditioning at a constant, increasing temperature delivers an increase in spawning success The researchers believe the process should be applicable to other species Fleming and Roberts (2001) found that temperatures between 17 and 19 °C were optimal for conditioning H laevigata In Western Australia, Freeman (2001) has found that H laevigata can be spawned all year round when water temperatures in the conditioning room ranged from 14.2–19.23 °C The most successful spawning events with highest egg productions occurred out of the ‘natural spawning season’ in most groups Spawning events during this period can be highly beneficial to farmers as they can take advantage of the enhanced growth of juveniles during the early summer months Animals can be weaned off the plates before the highest summer temperatures occur High water temperature during the weaning process can cause high mortalities in some regions of South Australia (Maguire 2001) Abalone can be stimulated with a single stimulus, or a combination of stimuli including temperature changes, treating seawater with UV, ozone or hydrogen peroxide, handling animals, or exposing them to air, depending on the species of interest (Maguire 2001) Hone et al (1999) outlined the procedure for spawning H laevigata as follows: place the abalone in clear aquaria and reduce the light and noise levels After a few hours of acclimation in ambient temperature water, activate the UV filter If after hours there is no activity, further stimulate the abalone by placing an immersion heater in the tanks and rapidly raise the temperature by 3–5 °C 8.3.2.2 Hatching Fertilised eggs from H laevigata hatch after approximately 16 hours at 18 °C and are called trochophore larvae Newly hatched trochophore larvae swim to the surface and then can be easily separated from the unhatched eggs and discarded egg cases by decanting off the Abalone Culture 241 top water layer into a clean tank for subsequent larval rearing (Maguire 2001) Abalone Farms Australia (AFA) in Tasmania use a system where the larvae hatch from the negatively buoyant eggs on the bottom of a tank and swim to the surface of the tank where there is a small weir on the sides that leads directly to the larval rearing tanks This system requires minimal labour (Cropp, pers comm 2002) The non-feeding larvae develop over about five days at 17 °C to 18 °C and about four days at 20 °C Densities are kept at less than 25/ ml to ensure the highest water quality, and to reduce the chances of bacteria growing on the tank surfaces (Maguire 2001) Survival rates of over 80% are common if proper care is taken during larval rearing (Fleming & Roberts 2001) 8.3.2.3 Nursery phase Towards the end of larval development, the larvae sink to the bottom of the container and begin exploring for a suitable surface for settlement (Maguire 2001) Benthic biofilm consisting of bacteria and mixed species of diatoms growing on PVC settlement plates have traditionally been used as a settlement substrate in abalone nurseries worldwide This process is unpredictable and larval settlement rates can be low (1–10% of larvae) (Daume 2003) Enhanced settlement up to 80% has been obtained in small-scale experiments through the use of the non-geniculate coralline red alga, Sporolithron durum (Daume 2003) Currently naturally developing diatom films on plastic plates are predominantly used as the settlement cue in abalone nurseries in Australia Some diatom species produce better settlement than others; for example Daume (2003) found that H laevigata settled particularly well on the diatom Navicula ramosissima Isolating particular diatom species and growing them in monoculture before inoculating settlement tanks in the nursery provides greater control This practice has not, however, been embraced by the industry because it is believed that the gain does not justify the extra costs involved in the scale-up diatom culture site Roberts and Lapworth (2001) explain that some diatom species are not good for settlement, and strains that are excessively mobile or form 3-dimensional colonies can prevent successful settlement Therefore con-specific substrate films may play a significant role in increasing settlement rates Hatcheries in Japan culture the microalgae Ulvella lens to improve settlement of the Japanese abalone Haliotis discus hannai (Takahashi & Koganezawa 1988) Takahashi and Koganezawa (1988) reported settlement rates of 67% on U lens, which was not previously grazed on by juvenile abalone Pre-grazed U lens yielded a settlement rate of 93–100% (Takahashi & Koganezawa 1988; Seki 1997) The first investigation of the settlement of Australian abalone species on U lens was conducted by Daume (2003), who found that settlement for H rubra was higher on U lens than on diatom films This study suggested that settlement plates seeded with U lens could induce high and consistent settlement of H rubra In addition, H laevigata settled well on U lens compared to some diatom films But more experiments are needed to explore the abalone growth and settlement rates achieved on different diatom species and cell densities (Daume 2003) Settlement and metamorphosis occur typically within one to three days after the larvae are introduced to the settlement tank (Maguire 2001) The transition from a free-swimming larva to a juvenile, living permanently on a hard surface, is a critical phase in the life of an abalone and mortality can be very high (∼90%) although the technology is improving (Daume 2003) 242 Recent Advances and New Species in Aquaculture 8.3.2.4 Growout phase The weight of the meat compared to the length of the shell is referred to as the meat weight: shell length ratio This ratio is important for farmers, because though the product is normally sold as net meat weight, shell length is normally used to assess the size of abalone Therefore, the aim of growout phase for farmers is to produce abalone with greater meat content Freeman (2001) found that abalone reared at high densities have a higher meat to shell length ratio than those cultured at lower densities In Australia, abalone is usually cultured on land using tanks, troughs or raceway systems Additionally, abalone can be reared in barrels or sea-cages hanging from buoys or rafts (Maguire 2001) There is currently much greater emphasis on land-based growout systems than sea-based systems in Australia A wide range of system designs are currently implemented in the country, ranging from deep to shallow and round to rectangular tanks An early land-based system in South Australia for H laevigata culture used a ‘surfboard’ design, which was shallow concrete tanks/raceways, usually with a length of approximately m These small ‘surfboard’ raceway tank systems are usually sited indoors or in shade cloth enclosures The ideal slope for a raceway is 1:100, which helps to prevent mass mortalities in the event of a pump failure by allowing the tanks to drain but also allowing the bottom surface to remain wet Shelters (hides) are not used since they disrupt the water flow (Freeman 2001) There is also a culture system based on much larger concrete tanks using the same principles of shallow water depth and high water exchange It employs a shaded outdoor system similar to the ‘surfboard’ system This is also currently being used in South Australia Some growers have successfully adapted the typical ‘Taiwanese’ culture method of deep tanks with strong aeration and numerous shelters for refuge (Forster 1996) These tanks are designed so they can be drained regularly to remove solid wastes They seem particularly well suited to H rubra, but are also used for H laevigata (Maguire 2001) A farm in Tasmania currently operates this system successfully to cultivate H laevigata Annual survival rates can be 80–95%, with growth rates of 20–30 mm a year in landbased systems for H laevigata in the southern regions of Australia (Fleming 1995) These rates are not always achieved, however, as growth rates vary significantly with the seasons (Fleming & Roberts 2001) Barrel or cage culture for abalone offers a low capital cost alternative, but can have high maintenance costs (Forster 1996) The barrels or cages can be from longlines supported by buoys or attached to rafts and large cages that can be placed on the ocean floor, provided that precautions are taken to prevent predation by crabs and starfish Supplying feed to submerged cages has been simplified by the development of a surface feeding system that pumps feed from a surface vessel into the rafts or cages on the ocean floor (O’Brien 1996a,b) The highest growth rates achieved in a trial involving a range of locations, culture systems (land- and sea-based) and species in Western Australia was with H laevigata grown in barrels at Albany (Fleming & Roberts 2001) The water flow rate is critical because it must be sufficient to encourage feeding behaviour, maintain dissolved oxygen levels and remove wastes, but not so fast as to wash away the feed before it can be consumed Stocking density and feed type are important factors when using this culture system In general, higher stocking densities in land-based systems, Abalone Culture 243 with most of the floor area covered by abalone, encourage more uniform distribution of H laevigata Throughout the growout phase, abalone densities are regularly reduced and size grading is carried out (Edwards et al 1999) Biofouling can greatly increase the maintenance costs of production systems and can directly smother the abalone by covering the respiratory pores New Australian technology aimed to reduce biofouling on molluscs, and plastic mesh based growout systems, may be critical for the success of sea-based abalone farming in Australia (Maguire 2001) 8.3.3 New Zealand Paua (Māori name) is the common name for abalone in New Zealand Three species of abalone occur naturally in New Zealand; black foot paua (Haliotis iris) (Fig 8.6) yellow foot paua (Haliotis australis) and white foot paua (Haliotis virginea) Black foot paua (Fig 8.8) is the largest abalone species in New Zealand and is most commonly found in shallow waters at depths less than m all around mainland New Zealand, Stewart Island and the Chatham Islands They often form large clusters in the sub-littoral zone on open, exposed coasts where drift seaweed accumulates and there is good water movement Black foot paua grow to about 180 mm in shell length (the legal size for wild harvesting is 125 mm, measured as the longest shell length) Fig 8.6 Paua abalone 244 Recent Advances and New Species in Aquaculture Fig 8.7 Trays with black foot paua abalone The New Zealand paua farming industry had its beginning in the mid-1980s when hatchery techniques were developed for the New Zealand species Paua farms in New Zealand have traditionally been land-based and configured to operate on flow-through water supply where the water is pumped from the sea, over the paua and then allowed to return to the sea Recirculation technology has gained favour in recent years and offers several advantages over flow-through by improving performance, raising efficiencies, reducing costs and reducing risk These advantages include maintaining consistent rearing temperatures, protecting farms from fluctuating environmental conditions and improving overall biosecurity Although the trend is towards recirculation, at least two farms currently operating use sea-based barrel culture technology; however, the focus for these is on the production of paua pearls, which employs a more extensive approach using freshly harvested seaweeds Early efforts on paua commercial production used seaweeds for feed However, now most land-based farms rely on manufactured pellet feeds because of their convenience, consistency of food quality, difficulties in obtaining sufficient quantities of seaweed and the additional benefit of reducing the black pigment in the foot Only black foot paua are currently farmed in New Zealand This is mainly because of the larger size of the black foot compared with the other two New Zealand species, and their iridescent shell coloration, utilised for the production of cultured paua pearls Paua Abalone Culture 245 aquaculture has excellent potential for New Zealand due to strong overseas demand and high prices attained for live meat (more than NZ$60 per kg) Currently, the industry in New Zealand is based around 11 farms, mostly onshore systems that on-grow hatchery-reared juveniles to market size for their meat The largest of these is OceaNZ Blue Ltd (OBL) in Northland, which produces the bulk of New Zealand’s farmed abalone OBL is on track to become the first 100 ton production facility in New Zealand and operates using a semi-recirculating system Two paua farms are focusing primarily on the production of juvenile paua for the purpose of reseeding to enhance coastal areas depleted of wild stocks This area of production is expected to gain momentum as enhancement efforts increase and the potential to identify reseeds from wild stock are realised through the development of molecular markers 8.4 8.4.1 TECHNOLOGICAL DEVELOPMENTS Polyploid induction Chromosome set manipulation in molluscs has received wide attention in the past two decades Research has primarily focused on the induction and evaluation of triploidy in bivalve species of commercial importance (Beaumont & Fairbrother 1991; Nell 2002) The principal value of triploids for aquaculture arises from their sterility, presumably because of failure in synapse of the three sets of chromosomes during meiosis Sterility may lead to faster growth of (adult) triploids owing to energy reallocation from reproduction to somatic growth Sterility may also result in better meat quality of triploids in association with their reduced spawning activities (Beaumont & Fairbrother 1991) Triploid animals are produced, by inhibiting the release of the first or second polar body, through the application of a chemical or environmental stress soon after fertilisation The retention of an extra set of chromosomes within the developing embryo results in an animal containing three sets of chromosomes per cell (triploid) instead of the usual two sets (diploid) Triploidy can be induced using multiple techniques 8.4.1.1 6- dimethylaminopurine exposure Fertilised eggs can be exposed to 100 μM solution of 6-DMAP (6-dimethylaminopurine) between 15 and 20 minutes post-fertilisation Following a 15-minute exposure to 6-DMAP, the eggs are rinsed and placed in hatching trays 8.4.1.2 Cytochalasin B (CB) exposure Induction of triploidy has been achieved applying CB at a concentration of 0.70 mg/L after 27 minutes for a duration of 10 minutes Eggs are then rinsed and placed in hatching trays 8.4.1.3 Temperature shock Exposure of fertilised eggs to °C at 15 minutes post-fertilisation for duration of 10 minutes and/or exposure to 26 °C water 15 minutes post-fertilisation has induced triploidy in various abalone species 246 Recent Advances and New Species in Aquaculture 8.4.2 Hybridisation Intraspecific (crossbreeding) and interspecific hybridisation within the family Haliotidae can be used as a strategy to improve the profitability of abalone farming An effort by farmers to reduce production costs rather than increase the price of their product may become a more realistic method of increasing profitability It would be expected that hybrids that display positive characteristics of heterosis would be an integral part of such an effort However, as pointed out by some authors, if hybrids are to be used for aquaculture, it is fundamental that they are made sterile or that efficient methods to prevent escape are developed, because of the abalone’s established ability to produce offspring among them (F2 progeny) and backcrossing with parental species (gene introgression risk) Escape could lead to a possible genetic impact of hybridisation on natural abalone populations Hybrids often have superior characteristics than their parents, such as greater in size, resistance to disease, number of offspring produced Heterosis, or hybrid vigour, is a term used to describe the phenomenon in which the performance of an F1 hybrid, generated by the crossing of two genetically different individuals, is superior to that of the better parent (heterobeltiosis) or average between both parents (middle parent heterosis) Heterosis has been extensively used in breeding programmes of aquaculture resources as a way for genetic improvement of cultured species (Hulata 2001) There are two major hypotheses that have been promulgated to explain heterosis: the dominance hypothesis and the overdominance hypothesis The dominance hypothesis suggests that heterosis is due to cancelling of deleterious recessives contributed by one parent, by dominant harmless alleles contributed by the other parent in the heterozygous F1 (Jones 1917) On the other hand, over-dominance hypothesis assumes that the heterozygous combination of the alleles at a single locus is superior to either of the homozygous combinations of the alleles at that locus (Shull 1908) As already pointed out in some research, intra-specific cross breeding has produced positive heterotic hybrid abalones With regard to the analysis of the genetic change in parent abalone and their hybrids, Wan et al (2001) obtained inter- and intra-population similarity indexes and genetic distances by Random Amplified Polymorphic DNA (RAPD) analysis of H discus hannai and H discus discus, and their reciprocal hybrids From the 113 bands of RAPD analysis some were special (diagnostic) for each kind of abalone and some others were common between two and three of the kinds Results of inter-population similarity indexes showed greater variation in hybrids, whereas genetic distances between the hybrids and the two parental species differed, being more similar to H discus discus for both hybrid crosses Later on, Wan et al (2004) continued their comparative studies on genetic diversities among these two parental species and their hybrids, in order to understand better the process of heterosis, using AFLP as molecular markers Results showed significant differences between parental populations in 88 out of 552 loci found In hybrids, more loci with lower frequency were amplified, whereas those with and 100% frequency were less amplified when compared with parents Lower similarity indexes and higher heterozygocity in hybrids resulted in an increased genetic diversity of hybrids And as noted before with RAPD analysis (Wan et al 2001), the genetic distances between reciprocal F1 generations and H discus discus were both smaller than those between hybrids and H discus hannai Recently, Liu and Zhang (2007) conducted a genetic study using AFLP markers to analyse the F1 intraspecific hybrid family of H discus hannai from two distinct geographical populations Results showed fragments exclusively for females, males and certain others common for both, some segregating in agreement with Mendelian 1:1 ratio and other with 3:1 ratio, Abalone Culture 247 showing ratios of segregation distortion of 27.4, 25.9 and 33.9%, respectively The authors hypothesised that segregation distortion may be associated with the incompatibility of genes between the two populations of H discus hannai used in this study (Liu & Zhang 2007) Aquaculture has produced hybrids to improve growth and survival in the past The yabby industry found that the crossing of female Cherax rotundus and male Cherax albidus produces only male progeny that grow faster than mixed sex groups of C albidus The results of trials under model pond conditions found the hybrid to have a final harvest value 4.6 times greater than that of C albidus yabbies (Lawrence 2004) This hybrid offers considerable potential to increase the profitability of yabby farming Hybrid striped bass are currently cultured in the United States and other countries, including Taiwan, Israel and Italy Hybrid striped bass are a cross between striped bass, Morone saxatilis and white bass, M chrysops When the female parent is a striped bass the hybrid is called a palmetto bass; when the female is a white bass the hybrid is called a sunshine bass Ludwig (2004) found that at days of age the palmetto bass are to mm long, while those of sunshine bass are only to mm in length Landau (1991) in an experiment using a hybrid from male blue catfish and female channel catfish, grown for 220 days in earthen ponds, found that the harvest of the hybrids was 13.5% greater than that of channel catfish Additionally, the hybrids were more easily captured by seining, were more uniform in size and had a greater dress-out percentage (weight after the head and skin were removed and it is eviscerated, divided by the live weight of the fish) Heterotic effects in the hybridisation of abalone have been reported as increased growth and survival (Leighton & Lewis 1982; Koike et al 1988) compared to those of the parent species Hoshikawa et al (1998) studied the heterotic effect of hybridisation on growth It was only observed at high water temperature (18 °C) in the form of superior growth rates and not at the lower water temperature (8 °C) in the cross between pinto abalone, Haliotis kamtschatkana and ezo abalone, H discus The daily shell growth was significantly higher in the hybrid at 18 °C with 33.4 to 55.6 μm/day compared to 6.5 to 10.9 μm/day for pinto abalone and 31.2 μm/day for ezo abalone (Hoshikawa et al 1998) Heterotic effect in growth and survival can also be observed at ambient temperature as demonstrated by Wang and Jiachun (1999), who found the growth and survival rates in the F1 offspring from the cross breeding of red abalone H rufescens and pacific abalone H discus hannai were higher than those of H discus hannai Juveniles of the hybrid between Haliotis rufescens and Haliotis fulgens, and also between H rufescens and Haliotis sorenseni displayed superior growth at ambient temperature than the parent species (Hoshikawa et al 1998) Hybrid abalone have been produced in Australia by crossing female Halitosis rubra and male H laevigata abalone (Freeman 2001) These individuals have been produced in an attempt to find an abalone that has the best characteristics in terms of growth rate, meat to shell ratio, meat texture and market appeal The ‘tiger ’ abalone which is a cross between a female H laevigata and a male H rubra, is commercially cultured in Tasmania by Tas Tiger Pty Ltd Hone et al (1999) indicated the tiger abalone has significant market value A hybrid between H laevigata and H scalaris has recently been produced at SAM abalone in Port Lincoln, South Australia It has shown a faster growth rate during the months between December to March than that of both parent species Fig 8.8 is a photograph of H scalaris, the hybrid, and H laevigata and clearly demonstrates the size difference This particular hybrid cross has also been found to occur in the wild The Western Australian Fisheries Department has specimens that have been found in the south west of Australia (Fig 8.9) Fig 8.8 Left to right: H scalaris, H laevigata × H scalaris (hybrid) and H laevigata Fig 8.9 Wild H laevigata, H laevigata × H scalaris (yybrid) and H scalaris found in Western Australia (Please see plate section for colour version of this figure.) Abalone Culture 8.5 249 FUTURE POSSIBILITIES In South America, the biggest constraint for the industry is considered to be the supply of abalone feed Some farmers are searching for a better supply of algae, including culturing Macrocystis pyrifera as the solution while some others are experimenting with manufactured diets of their own production or from domestic and foreign feed-producing mills In New Zealand, prohibitive harvesting costs and limits on harvesting have resulted in abalone farmers using artificial feed pellets Since abalone needs to actively search for static artificial food, studies are being undertaken to improve the attractiveness of such feeds by the addition of chemical attractants, feeding stimulants or dried seaweed fragments (Allen et al 2006) On the other hand, artificial diets have been considered expensive and unsuitable for ocean-based longline culture of abalone and suitability of a variety of seaweeds is being investigated (Qi et al 2010) Abalone production systems need to optimise culture configurations to improve productivity In Chile, efficiencies of basket and lantern nets suspended in seawater tanks were compared for growth and survival of juvenile abalone (Pereira & Rasse 2007) Lantern systems were found to have a larger carrying capacity while occupying less water column space The lantern nets provided better growth, and were more economical and easier to handle (Pereira & Rasse 2007) Recirculating aquaculture systems (RAS) are considered to have reduced environmental impacts Installation of baffles within the RAS culture tanks has been trialled to allow high-density culture (Park et al 2008) Recently, Integrated multi-trophic aquaculture (IMTA) involving integration of fed species and extractive species been developed and is gaining recognition as a sustainable approach to aquaculture (Nobre et al 2010) In South Africa, IMTA has been implemented using seaweed Ulva lactuca and abalone Haliotis midae, where the algae take up the dissolved inorganic nutrients from the system and the produced algal biomass provides renewable feed for the other cultivated species, abalone (Nobre et al 2010) Another major challenge for the industry is to diversify the market Most abalone were sold in Japan in the past but now Chinese, United States and European companies are making big efforts to develop the market and specifically the presentation of canned abalone 8.6 REFERENCES Allen, V.J., Marsden, I.D., Ragg, N.L.C & Gieseg, S (2006) the effects of tactile stimulants on feeding, growth, behaviour and meat quality of cultured blackfoot abalone, Haliotis iris Aquaculture, 257, 294–308 Beaumont A.R & Fairbrother J.E (1991) Ploidy manipulation in molluscan shellfish: a review Journal of Shellfish Research, 10, 1–18 Cropp, M (2002) Abalone Farms Australia Pty Ltd Personal Communication, Bicheno Tasmania, (Owner/ Manager) Daume, S (2003) Early life history of abalone (Haliotis rubra and H laevigata): Settlement, survival and early growth, Fisheries Research Contract Report Department of Fisheries, Perth, Western Australia Edwards, S., Ralph, J & Geraghty, D (1999) Movement of gut contents in blacklip abalone (Haliotis rubra) is not mediated by peristalsis In: Proceedings of the 6th Annual Abalone Aquaculture Workshop, April, 1999, NSW (ed P Hone), pp 102–111 Fisheries Research and Development Corporation, Sydney 250 Recent Advances and New Species in Aquaculture Enríquez, R & Villagrán, R (2008) La experiencia del desarrollo del cultivo de abalón (Haliotis spp.) en Chile: Oportunidades y desafios Revue Scientifique et Technique (International Office of Epixootics), 27, 103–112 Fleming, A (2008) Global sustainability targets of Australian abalone farmers Accessed July 2010 Available from http://www.thefishsite.com/articles/567/global-sustainability-targets-of-australianabalone-farmers) Fleming, A.E (1995) Growth, intake, feed conversion efficiency and chemosensory preference of the Australian abalone, Haliotis rubra Aquaculture, 132(3–4), 297–311 Fleming, A.E & Roberts, R (eds) (2001) Proceedings of the 7th Annual Abalone Aquaculture Workshop (Australasian abalone aquaculture Conference, Dunedin, New Zealand) FRDC Abalone Aquaculture Subprogram, Williamstown Victoria Flores-Aguilar, R., Gutiérrez, A., Ellwanger, A & Searcy-Bernal, R (2007) Development and current status of abalone aquaculture in Chile Journal of Shellfish Research, 26, 705–711 Food and Agriculture Organisation of the United Nations (FAO) (2009) World aquaculture production FAO Fisheries and Aquaculture Department, online database Available from http://www.fao.org/ fishery/statistics/global-aquaculture-production/en Food and Agriculture Organisation of the United Nations (FAO) (2010) FAO Fisheries and Aquaculture Information and Statistics Service Available from http://www.fao.org/figs/servelet Forster, A (ed.) (1996) Proceedings of the Abalone Aquaculture Workshop, December (1995), Albany, Western Australia Aquaculture Development Council and Fisheries Department of Western Australia Freeman, K.A (2001) Aquaculture and related biological attributes of abalone species in Australia – a Review Fisheries Research Report, 128, Fisheries Western Australia, Perth Freeman, K.A., Daume, S., Rowe, M., Parsons, S., Lambert, R & Maguire, G.B (2006) Effects of season, temperature control, broodstock conditioning period and handling on incidence of controlled and uncontrolled spawning of greenlip abalone (Haliotis laevigata Donovan) in Western Australia Journal of Shellfish Research, 25(1), 187–194 Godoy C., Jerez, G & Ponce, F (1992) The introduction of abalone into Chile In: Abalone of the World: Biology, Fisheries and Culture (eds S.M Tegner & S Guzmán del Próo) pp 485–488 London, Blackwell Scientific Publishers Hone, P.W., Madigan, S.M & Fleming, A.E (1999) Abalone hatchery manual for Australia South Australian Research and Development Institute, Adelaide Hoshikawa, H., Sakai, Y & Kijima, A (1998) Growth characteristics of the hybrid between pinto abalone, Haliotis kamtschatkana Jonas, and ezo abalone, H discus hannai Ino, under high and low temperature Journal of Shellfish Research, 17(3), 673–677 Hulata, G (2001) Genetic manipulations in aquaculture: a review of stock improvement by classical and modern technologies Genetica, 111, 155–173 Jia, Jiansan & Chen, Jiaxin (2001) Sea farming and sea ranching in China FAO Fisheries Technical Paper T418 Jones, D.F (1917) Dominance of linked factors as a means of accounting for heterosis National Academy of Science (USA) 3, 310–312 Koike, Y., Sun, Z & Takashima, F (1988) On the feeding and growth of juvenile hybrid abalones Suisanzoshoku, 36(3), 231–235 Lafarga-De la Cruz, F., Aguilera-Moz, F., Díaz Pérez, N & Gallardo-Escaráte, C (2010) Hatchery performance of interspecific hybrids between California red abalone (Haliotis rufescens) and Japanese abalone (H discus hannai) to diversify Chilean abalone aquaculture Aquaculture (submitted) Landau, M (1991) Introduction to Aquaculture Benjamin/Cummings Publishing Company, Inc Lawrence, C.S (2004) All-male hybrid (Cherax albidus × Cherax rotundus) yabbies grow faster than mixed-sex (C albidus × C albidus) yabbies Aquaculture, 236(1–4), 211–220 Leighton, D.L & Lewis, C.A (1982) Experimental hybridisation in abalones International Journal of Invertebrate Reproduction, 5, 273–282 Liu, X & Zhang, G (2007) Genetic analysis of segregation distorsion of AFLP markers in an F1 population of the Pacific abalone Marine Sciences, 31(10), 70–76 Ludwig, G.M (2004) Tank culture of larval sunshine bass, Morone chrysops (Rafinesque) × M saxatilis (Walbaum), at three feeding levels, (2003), Aquaculture Research, 34(14), 1277–1285 Maguire, G.B (2001) Farming Abalone Fisheries Western Australia, 7, 1–8 Morse, D.E., Duncan, H., Hooker, N & Morse, A (1976) Hydrogen peroxide induces spawning in mollusks, with activation of prostaglandin endoperoxide synthetase Science, 196, 298–300 Abalone Culture 251 Nell, J.A (2002) Farming triploid oysters Aquaculture, 210, 69–88 Nobre, A.M., Robertson-Anderson, D., Neori, A & Sankar, K (2010) Ecological-economic assessment of aquaculture options: comparison between abalone monoculture and integrated multi-trophic aquaculture of abalone and seaweeds Aquaculture, 306, 116–126 O’Brien, D (1996a) Preliminary analysis of the production costs and returns involved in abalone farming In: Proceedings of the Abalone Aquaculture Workshop, December, 1995, Albany, Western Australia (ed A Forster), pp 67–83 Aquaculture Development Council and Fisheries Department of Western Australia O’Brien, D (1996b) Growing abalone at sea – the latest ideas from Tasmania and further afield In: Proceedings of the Abalone Aquaculture Workshop, December, 1995, Albany, Western Australia (ed A Forster), pp 28–35 Aquaculture Development Council and Fisheries Department of Western Australia Oakes, F.R & Ponte, R.D (1996) The abalone market: Opportunities for cultured abalone Aquaculture, 140(1–2), 187–195 Park, J., Kim, H-B., Kim, P-K & Jo, J-Y (2008) The growth of disk abalone, Haliotis discus hannai at different culture densities in a pilot-scale recirculating aquaculture system with a baffled culture tank Aquacultural Engineering, 38, 161–170 Pereira, L & Rasse, S (2007) Evaluation of growth and survival of juveniles of the Japanese abalone Haliotis discus hannai in two culture systems suspended in tanks Journal of Shellfish Research, 26, 769–776 Plant, R., Mozquiera, A., Day, R & Huchette, S (2003) Conditioning and spawning blacklip abalone (Haliotis rubra) Proceedings from the 9th annual abalone aquaculture workshop, Queenscliff, Australia Qi, Z., Liu, H., Li, B., et al (2010) Suitability of two seaweeds, Gracilaria lemaneiformes and Sargassum pallidum, as feed for the abalone Haliotis discus hannai Ino Aquaculture, 300, 189–193 Roberts, R.D & Lapworth, C (2001) Effect of delayed metamorphosis on larval competence, and postlarval survival and growth, in the abalone Haliotis iris (Gmelin) Journal of Experimental Marine Biology & Ecology, 258, 1–13 Seki, T (1997) Biological studies on seed production of northern Japanese abalone Bulletin of the Tohoku National Fisheries Research Institute, 59, 1–71 Shull, G.H (1908) The composition of a field of maize American Rare Breed Association, 4, 296–301 Subpesca (2006) Subsecretaría de Pesca Resolución Final No 4282 14 de Diciembre del 2005, Valparaíso, Chile Takahashi, K & Koganezawa, A (1988) Mass culture of Ulvella lens as a feed for abalone Halitosis discus hannai NOAA Technical report NMFS, 70, 25–36 Wan, F., Bao, Z., Zhang, Q & Wang, X (2004) Comparative Studies on the Molecular Genetic Diversities among Haliotis discus hannai, H discus discus and their hybrids High Technology Letters, 10(3), 93–96 Wan, J.X., Wang, J., Pan, B., et al (2001) RAPD analysis of the genetic change in parent abalone and their hybrids Periodical of Ocean University of China, 31(4), 506–512 Wang, R & Jiachun, F (1999) Artificial breeding of red abalone, Haliotis rufescens, and cross breeding with Pacific abalone, H discus hannai Ino Journal of Dalian Fisheries College/Dalian Shuichan Xueyuan Xuebao, 14(3), 64–66  ... Currently, the abalone industry is supported by two foreign species: Haliotis rufescens, red abalone from California and Japanese or ezo abalone, Haliotis discus hannai from Japan Red abalone was... consumption of abalone in China is almost entirely in the canned form In regions such as Japan and the USA, canned abalone is generally not considered a premium product Canned abalone has a traditional... distribution point for canned abalone destined for mainland China is through Hong Kong (Oakes & Ponte 1996) Abalone Culture 8.2.3 233 USA In the USA there is a traditional market for abalone, which is mainly