ABALONE (Haliotis Asinina L): 5

Home , Haliotis asinina, Haliotis australis, Haliotis ovina

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Oseana, Volume XXX, Nomor 2, 2005 : 1 - 10 ISSN 0216-1877

ABALONE (Haliotis asinina L): 5. EARLY JUVENILE REARING AND ONGROWING CULTURE

Oleh

Dwi Eny Djoko Setyono 1)

ABSTRAK

ABALONE (Haliotis asinina L): 5. PEMELIHARAAN ANAKAN PADA TAHAP AWAL DAN BUDIDAYA PEMBESARAN. Minat untuk membudidayakan abalon di banyak negara di dunia masih terus berkembang dan tumbuh pesat mengingat harga jual abalon cukup tinggi dan cenderung terus meningkat. Berbagai macam teknik budidaya digunakan untuk membudidayakan abalon, termasuk abalon tropis (Haliotis asinina). Indonesia adalah negara kepulauan, memiliki wilayah perairan pantai yang luas dan cocok untuk membudidayakan abalon. Perairan laut di Indo- nesia sangat produktif, pakan alami untuk abalon (makro-algae) sangat melimpah. Semua metoda budidya abalon dapat diterapkan di Indonesia, tergantung pada tujuan dan sistem budidaya yang dipilih. Pada tulisan ini diuraikan lebih lanjut tentang pemeliharaan anakan pada tahap awal, budidaya pembesaran anakan hingga mencapai ukuran layak jual, dan pakan alami (makro-algae) yang cocok dan disukai oleh abalon tropis.

INTRODUCTION There have been extensive studies on commercially important abalone species for Abalone is a very popular and delicious aquaculture. Every country has cultivated its food. Therefore these animals have a high de- own native species because of ecological con- mand with a high market price. However, aba- sideration, and it is simpler to deal with the ani- lone production from wild fisheries is continu- mals in relation to water quality (temperature ing to decline in the recent decades. Therefore, and salinity) and suitable natural food. The na- commercial abalone farms throughout the world tive cultured abalone species of different coun- are now intensively producing abalone to meet tries is summarised in Table 1. increasing market demand. The worldwide in- Successful effort on hatchery techniques terest in culturing abalone is still growing and, and greater market value of some species, de- in the near future, it is expected to grow even liberated several countries introduce a new spe- more as a result of the competitive markets for cies from other geographical different area. The live abalone around the world (VIANA, 2002). introduced new species of abalone can grow

1) Bidang Sumberdaya Laut, Pusat Penelitian Oseanografi-LIPI, Jakarta

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very well in a controlled environment. They fore, depends upon the goal and the extent of grow even better than in their origin. However, the culture system. there are ecological considerations in culturing exotic species, including possible ecological EARLY JUVENILE REARING impacts, genetics and diseases. A variety of techniques are used to raise In recent years, many countries have de- numerous species of abalone, including veloped abalone hatcheries to produce seed for Haliotis diversicolor in Taiwan (CHEN, 1984), enhancement of natural stock and for growing Haliotis discus hannai in Korea (FAO, 1990), in commercial farms. Culture techniques for Haliotis australis and Haliotis iris in New tropical abalone have been adapted mainly from Zealand (TONG & MOSS, 1992; CLARKE & the studies done on H. diversicolor supertexta CREESE, 1988), Haliotis fulgen in California (JARAYABHAND & PAPHAVASIT, 1996). (AVILES & SHEPHERD, 1996), and the tropical Although much can be learn from well-estab- abalone, Haliotis asinina in Philippines lished techniques, many aspects of abalone (CASTANOS, 1997) and in Indonesia culture must be tailored to suit the local (SETYONO, 2003). species, environmental conditions, and There are two different path ways by possibly more importantly, the economic and which the cultured abalone will ultimately reach political conditions of the country (FLEMING the consumer. The first path is using hatchery & HONE, 1996). The basic established tech- reared juveniles for reseeding depleted area, to niques need to be optimised for specific restore the natural abalone population to a species and geographical areas. capable level of maintaining a fishery production. The second path is commercially rising A major problem in abalone seed pro- abalone to market size and selling it directly to duction in the hatcheries was the high mortal- the consumer. There are three different ity during the settlement phase (EBERT & methods of commercially culturing abalone to a HOUK, 1984). The success of settlement market size. These are: land-based farming in depends on competent larvae making contact tanks, raceways, and ponds with intensive feed- with a suitable substratum before the larvae ing; containment rearing in offshore areas; and starve to death (MCSHANE, 1992). CAPINPIN ocean ranching in closed private areas (HAHN, et al. (1998) and SETYONO (2003) noted that 1989). SETYONO (1997) has noted some advan- the most important for successful larval settle- tages and disadvantages of these method. To ment for tropical abalone (H. asinina) are choose which method should be used to grow suitable substrates and sufficient diatoms. out abalone, there are many factors to be con- The improvements of culture techniques sidered, including economical, ecological, geo- in recent years have had a significant impact on graphical, and even political. abalone production. Besides suitable substrate Indonesia is an archipelago country and and sufficient diatoms, survival and growth has many coastal areas that are suitable for rates of early juvenile stages can be improved growing abalone. The ocean is very productive by developing a reliable system for maintaining and natural food for abalone (macroalgae: water quality. For example, the system could Gracilaria spp., Hypnea spp., Ulva spp., employ a bio-membrane filter grown on coral Kappaphycus spp.) is very abundant. All of the debris and the water be treated through UV- mentioned culture methods, whether land-based light before entering the rearing tanks (NIE et farming, containment rearing in offshore areas, al., 1996), and the system should provide suit- and/or ocean ranching, are suitable to be set up able water temperature (PAUL & PAUL, 1981) in this country. The acceptable method, there- and salinity (SINGHAGRAIWAN et al., 1992).

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SETYONO (2003) reported that veligers able diatom species for feeding early juvenile of H. asinina settled within 3-4 days. Settle- H. asinina is still unknown. For example, ment and feeding of early juveniles is crucial. Chaetoceros spp. was the most accepted dia- At this stage, high mortality occurs, especially tom for H. kamtschatkana (PAUL et al., 1977), when diatoms as a main food source are limited. and Tetraselmis suecica was used to feed newly Juvenile H. asinina fed on diatoms, Nitzchia settled H. rufescens (OWEN et al., 1984). More spp., grew to approximately 0.5 mm in shell variables in food, including the size and spe- length (SL) in 2 weeks and 1.5 mm SL in 2 cies of diatoms, will likely improve the success months. A significant growth in SL occurred of juvenile rearing. after the second month, and juveniles reached a size of 10-20 mm SL in 3-5 months. After reach- ONGROWING CULTURE ing a size of 10 mm SL, juvenile H. asinina are capable to feed on soft part of macroalgae A variety of techniques are used to raise (Acanthophora, Gracilaria, and Hypnea). The numerous species of abalone. Tropical abalone fact that some juveniles reached sizes larger than (H. asinina) is a hardly marine snail. The juve- 30 mm SL within six months of rearing revealed nile can be reared on land in tanks made from that H. asinina has the potential to grow to concrete or fibre glass, or in the sea using a net market size cocktail abalone (50-60 mm SL) in cages constructed by fitting together wooden less than 2 years. This ongrowing time can be or steel frames and covering them with netting shortened by provided the juvenile with good material, and/or in a barrel. The structure of net rearing conditions including good water cages can be rectangular (Figure 1), circular quality and flow, and suitable and accessible (Figure 2), and also can used unused tyre food. covered by net (Figure 3). Shelters are set High variability in growth rate is com- inside the cage using a polyvinyl chloride (PVC) mon in Haliotis spp. (DAY & FLEMING, 1992). pipe, and a closed meshed window is fixed to LILLEY (2001) found that an extensive growth provide access into the cage. Cages were then heterogeneity occurred in the New Zealand suspended below the water surface from blackfoot abalone, H. iris. Abalone in the larger a floating raft offshore. size-class was found to be competitively Maximisation of growth is an important superior. Therefore, regular grading, for example factor for successful commercial aquaculture. every 2 months, is needed to prevent grazing A variety of factors such as food quality (MAI competition. SETYONO (2003) has observed et al., 1995), stocking density (MGAYA & that large juveniles climbed on top of small MERCER, 1995), and water quality (FALLU, juveniles. The behaviour of large juveniles may 1991) are known to influence the growth of limit the movement of small juveniles, affecting juvenile abalone. the uptake of food. There was evidence that Clumping/aggregation behaviour exist in growth of small abalone improved in the H. asinina. SETYONO (2003) reported that in absence of larger conspecifics (MGAYA & the sized group of 40.1-47.0 mm SL, the mean MERCER, 1995). daily increase in shell length and body weight Creeping juveniles of hatchery-reared was higher in juveniles reared in higher stock- tropical gastropods are mostly fed with ing density than in lower stocking density. This Navicula spp. and Nitzchia spp. phenomenon also occurred in small sized juve- (JARAYABHAND & PAPHAVASIT, 1996; nile H. tuberculata in which the biomass growth DWIONO et al., 1997; SETYONO & DWIONO, increased as density increased (MGAYA & 1998). However, the most acceptable and suit- MERCER, 1995).

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There is density-dependence for space tainment. In a commercial application, net cages and food in juvenile H. asinina. SETYONO can be replaced by cages constructed from (2003) found that the optimum stocking den- wood, bamboo and/or rattan which provide sity in an outdoor tanks culture is 50 and 38 more shelter for the juveniles but enough water juveniles m-2 for juveniles with initial size of flow through the cages. It is possible to rear <40 mm SL and >40 mm SL, respectively. While abalone in a polyculture system. For example: the optimum stocking density in cages offshore polyculture of abalone and pearl oyster, or was 80 juveniles m-2. abalone and seaweed culture. This system will Juvenile H. asinina reared in an outdoor optimise the use of such floating structures (raft tank had feeding rates on fresh macroalgae and buoys). In the first example, pearl oysters (Gracilaria spp.) ranged from 20% to 23% of can be suspended at a deeper position (5-10 m) body weight each day (SETYONO, 2003), while while abalone an be suspended near the sur- juvenile reared in cages offshore had feeding face (1 m). Fouling algae on the raft (Gracilaria rates of 15-25% of body weight per day spp. and Hypnea spp.) could be used to feed (CAPINPIN et al., 1999). Generally, feeding rates abalone. In the second example, seaweed could per unit of biomass are higher in smaller and be cultured in the surface, while abalone could fast-growing juveniles than in larger abalone be suspended in a deeper position (4 m). (MARSDEN & WILLIAMS, 1996). Higher feeding rate occurred at a lower stocking density is FOOD PREFERENCES common in haliotids (MARSDEN & WILLIAMS, 1996; SETYONO, 2003). Variation in feeding rates Investigation into feeding behaviour, of abalone are not unusual as abalone are known especially the effect of diet on juvenile growth to be erratic feeders, sensitive to a number of is important. The right type and quantity of environmental and physiological influences algal diets could increase the growth of juve- (GREENIER & TAKEKAWA, 1992). nile abalone. Studies on feeding habit show that SETYONO (2003) reported that growth abalone like to feed on the soft part of algae. of cultured juvenile H. asinina in cages offshore They prefer Ulva to Gracilaria (CHEN, 1984). was not affected by the setting position (depth) Previous work shows that H. asinina preferred of the cage. The daily increase in shell length red algae to brown algae (TAHIL & JUINIO- and body weight of cultured abalone offshore MENEZ, 1999). SETYONO (2003) reported that are affected by environmental factors such as juvenile H. asinina reared in cages offshore water quality (HARRIS et al., 1999), waves and preferred first to graze on Gracilaria, followed currents (CHAN et al., 1985), feeding rates and by Hypnea, Kappaphycus and Ulva, and then food consumption rates (MARSDEN & lastly on Laurencia. These macroalgae were WILLIAMS, 1996). abundant in coastal areas around Lombok Haliotis asinina are hardy animals. Sur- Island. vival rates on juveniles cultured in net cages Although many species of seaweed can offshore of Pemenang, West Lombok was be used to feed abalone, only Gracilaria meets 93-95% (SETYONO, 2003) and in Philippines the requirement of ample supply and low price. was 94-98% (CASTANOS, 1997). Moreover, The use of Gracilaria to feed juvenile H. asinina survival rates are not effected by density, type promoted high growth in the long-term and is of structure and setting position (depth). considered suitable for abalone farming as re- In practical, juvenile H. asinina can be ported by CAPINPIN & CORRE (1996). It is not reared in a structure which provide suitable surprising that almost all abalone farmed in Tai- shelter but enough water flow through the con- wan use Gracilaria as the main food (CHEN,

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1984). The availability and suitability of growth of the tropical abalone Haliotis Gracilaria to feed abalone, H. asinina, was asinina in cage culture. Aquaculture practised in Thailand (SINGHAGRAIWAN & 171: 227-235. SASAKI, 1991) and Philippines (CAPINPIN & CASTANOS, M. 1997. Abalone R & D at AQD. CORRE, 1996; CAPINPIN et al., 1999). SEAFDEC Asian Aquaculture 19: 18-23. SETYONO (2003) observed that juvenile CHAN, W.L., B. TIENSONGRUSMEE, S. H. asinina fed with a single-species diet of PONTJOPRAWIRO and I. SOE- Gracilaria or Ulva has better growth rates than DJARWO 1985. Note on site selection. the juveniles fed with single diet of Laurencia, In: Seafarming workshop report. FAO/ or Kappaphycus or Hypnea. CAPINPIN & UNDP Seafarming Development Project. CORRE (1996) found that juvenile H. asinina p. 24-30. fed with Gracilaria grew faster than those fed CHEN, H-C. 1984. Recent innovation in cultiva- with Kappaphycus. However, SETYONO (2003) tion of edible molluscs in Taiwan, with reported that the highest growth rate was found special reference to the small abalone in juveniles which were fed with mixed diet of Haliotis diversicolor and the hard clam macroalgae. It is suggested that mixed diet of Meretrix lusoria. Aquaculture 39: 11-29. macroalgae provide the juveniles with suited CLARKE, C.B. and R.G. CREESE 1988. On- nutritional requirement. growing cultured abalone (Haliotis iris) in northern New Zealand. Journal of REFERENCES Shellfish Research 17: 607-613. COUNIHAN, R.T., D.C. MCNAMARA, D.C. AVILES, J.G.G. and S.A. SHEPHERD 1996. SOUTER, E.J. JEBREEN, N.P. PRESTON, Growth and survival of the blue abalone C.R. HOHNSON and B.M. DEGNAN Haliotis fulgens in barrels at Cedros 2001. Pattern, synchrony and predictabil- Island, Baja California, with a review of ity of spawning of the tropical abalone abalone barrel culture. Aquaculture 140: Haliotis asinina from Heron Reef, Aus- 169-176. tralia. Marine Ecology Progress Series BERNAL, R.S., A.E. SALAS-GARZA, R.A. 213: 193-202. FLORES-AGUILAR and P.R. DAY, R.W. and A.E. FLEMING 1992. The deter- HINOJOSA-RIVERA 1992. Silmu- minants and measurement of abalone taneous comparison of methods for growth. In: Abalone of the world. (SHEP- settlement and methamorphosis induc- HERD, S.A., M.J. TEGNER and S.A. tion in the red abalone (Haliotis GUZMAN DEL PROO eds.). Blackwells, rufescens). Aquaculture 105: 241-250. Oxford. p. 141-168. CAPINPIN, Jr.E.C. and G. CORRE 1996. Growth DWIONO, S.A.P., P.C. MAKATIPU and rate of the Philippine abalone, Haliotis PRADINA. 1997. A hatchery for topshell asinina fed an artificial diet and (Trochus niloticus) in Eastern Indone- macroalgae. Aquaculture 144: 81-89. sia. In: Trochus: status, hatchery prac- CAPINPIN, Jr.E.C., V.C. ENCENA II and N.C. tice and nutrition (LEE, C. E. & P.W. BAYONA 1998. Studies on the repro- LYNCH eds.) ACIAR Proceeding 79: ductive biology of the Donkey's ear aba- 33-37. lone Haliotis asinina in Linne. Aqua- EBERT, E.E. and J.L. HOUK 1984. Elements and culture 166: 141-150. innovations in the cultivation of red aba- CAPINPIN, Jr.E.C., J.D. TOLEDO, V.C. ENCENA lone, Haliotis rufescens. Aquaculture II and M. DOI 1999. Density dependent 39: 375-392.

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FALLU, R. 1991. Abalone Farming. Fishing Japanese Society of Scientific Fishe- News Books, Oxford. 195 p. ries 47: 151-159. FAO, 1990. Training manual on artificial breed- LILLEY, C. 2001. Growth heterogeneity in ing of abalone (Haliotis discus hannai) Haliotis iris: the effects of size-grading, in Korea DPR. Training manual 7: 107 p. stocking density and food availability FAO, 1996. FAO yearbook vol. 82. Fishery statis- on abalone growth rates. Unpublished tic. Capture production. FAO, Rome. 148 p. M.Sc. thesis. University of Otago, FLEMING, A.E. and P.W. HONE 1996. Abalone Dunedin, New Zealand. 144 p. aquaculture: an introduction. Aquacul- MAI, K., J.P. MERCER and J. DONLON 1995. ture 140: 1-4. Comparative studies on the nutrition of GREENIER, J.L. and J.Y. TAKEKAWA 1992. two species of abalone, Haliotis Growth models and food conversion of tuberculata Linnaeus and Haliotis cultured juvenile red abalone (Haliotis discus hannai Ino. 3. Response of rufescens). In: Abalone of the word: bio- abalone to various levels of dietary lipid. logy, fisheries and culture. (SHEPHERD, Aqua-culture 134: 65-80. S.A., M.J. TEGNER and S.A. GUZMAN MARSDEN, D.I. and P.M.J. WILLIAMS 1996. DEL PROO eds.). Blackwells, Oxford. Factors effecting the grazing rate of the Pp. 527-537. New Zealand abalone Haliotis iris HAHN, K.O. 1989. Abalone aquaculture in Cali- Martyn. Journal of Shellfish Research fornia. In: Handbook of culture of aba- 15: 401-406. lone and other marine gastropods MCSHANE, P.E. 1992. Early life history of aba- (HAHN, K.O. ed. ). CRC Press, Inc. Boca lone: a review. In: Abalone of the word: Raton, Florida. p. 221-225. biology, fisheries and culture. (SHEP- HARRIS, J.O., G.B. MAGUIRE, S.J. EDWARDS HERD, S.A., M.J. TEGNER and S.A. and D.R. JOHNS 1999. Low dissolved GUZMAN DEL PROO eds.). Blackwells, oxygen reduces growth rate and oxygen Oxford. Pp. 121-131. consumption rate of juvenile greenlip MGAYA, Y.D. and J.P. MERCER 1995. The abalone, Haliotis laevigata Donovan. effect of size grading and stocking Aquaculture 174: 265-278. density on growth performance of HOOKER, S.H. and R.G. CREESE 1995. Repro- juvenile abalone, Haliotis tuberculata duction of paua, Haliotis iris Gmelin Linnaeus. Aquaculture 136: 297-312. 1791 (Mollusca: Gastropoda), in North- MOSS, G.A. 1999. Factor affecting settlement eastern New Zealand. Marine and and early post-settlement survival of the Freshwater Research 46: 617-622. New Zealand abalone Haliotis austra- JARAYABHAND, P. and N. PAPHAVASIT 1996. lis. New Zealand Journal of Marine and A review of the culture of tropical aba- Freshwater Research, 33: 271-278. lone with special reference to Thailand. NIE, Z.Q., M.F. JI and J.P. YAN 1996. Prelimi- Aquaculture 140: 159-168. nary studies on increased survival and KEESING, J.K. and F.E. WELLS 1989. Growth of accelerated growth of overwintering ju- the abalone, Haliotis roei Gray. Austra- venile abalone, Haliotis discus hannai lian Journal of Marine and Freshwa- Ino. Aquaculture 140: 177-186. ter Research 40: 199-204. OWEN, B., L.H. DISALVO, E.E. EBERT and E. KOJIMA, H. 1981. Mortality of young Japanese FONCK 1984. Culture of California red black abalone Haliotis discus discus abalone, Haliotis rufescens Swainson after transplantation. Bulletin of the (1822), in Chile. The Veliger 27: 101-105.

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PAUL, A.J. and J.M. PAUL 1981. Temperature SINGHAGRAIWAN, T., M. DOI and M. and growth of maturing Haliotis SASAKI 1992. Salinity tolerance of kamtschatkana Jonas. The Veliger 23: juvenile Donkey's ear abalone Haliotis 321-324. asinina Linne. Thai Marine Fisheries PAUL, A.J., J.M. PAUL, D.W. HOOD and R.A. Research Bulletin 3: 71-77. NEVE 1977. Observation on food pre- TAHIL, A.S. and M.A. JUINIO-MENEZ 1999. ferences, daily ration requirement and Natural diet, feeding periodicity and growth of Haliotis kamtschatkana functional response to food density of Jonas in captivity. The Veliger 19: 303- the abalone, Haliotis asinina L., (Gas- 309. tropoda). Aquaculture Research 30: 95- PENA, J.B. 1986. Preliminary study on the in- 107. duction of artificial spawning in Haliotis TONG, L.J. and G.A. MOSS 1992. The New coccinea canariensis Nordsieck (1975). Zealand culture system for abalone. In: Aquaculture 52: 35-41. Abalone of the world: biology, fisher- SALES, J. and P.J. BRITZ 2001. Review: research ies, and culture (SHEPHERD, S.A., M.J. on abalone (Haliotis midae L.) cultiva- TEGNER and S.A. GUZMAN DEL PROO tion in South Africa. Aquaculture eds.). Blackwells, Oxford. p. 583-591. Research 32: 863-874. SETYONO, D.E.D. 1997. UKI, N and S. KIKUCHI 1982. Influence of food SETYONO, D.E.D. 2003. Reproductive biology levels on maturation and spawning of and seed production techniques for the abalone, Haliotis discus hannai re- tropical abalone (Haliotis asinina L.) in lated to effective accumulative tempera- eastern Indonesia. Otago University, ture. Bulletin of the Tohoku Regional New Zealand. PhD thesis, 274 p. Fisheries Research Laboratory 45: 45- SETYONO, D.E.D. and S.A.P. DWIONO 1998. 53. Rearing of juvenile green snail (Turbo UKI, N and S. KIKUCHI 1984. Regulation of marmoratus) fed on natural food and maturation and spawning of abalone, single species diatom (Navicula spp..) Haliotis (Gastropoda) by external envi- cultured on coral rubble and bivalve ronmental factors. Aquaculture 39: 247- shell. (Paper in Indonesian with abstract 261 in English). Perairan Maluku dan VIANA, M.T. 2002. Abalone aquaculture, an Sekitarnya 12: 1-9 overview. World Aquaculture 33: 34-39. SINGHAGRAIWAN, T. and M. SASAKI 1991. YOO, S.K. 1989. Abalone farming in Korea. In: Breeding and early development of the Handbook of culture of abalone and donkey's ear abalone, Haliotis asinina other marine gastropods (HAHN, KO. Linne. Thailand Marine Fisheries ed.). CRC Press, Inc. Boca Raton, Research Bulletin 2: 83-94. Florida. p. 225-263.

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Table 1. Countries and their cultured native abalone species.

Countries Cultured abalone Sources

Ireland Haliotis tuberculata MGAYA & MERCER, 1995 Spain Haliotis canariensis PENA, 1986 Mexico Haliotis fulgen AVILES & SHEPHERD, 1996 Haliotis rufescens BERNAL et al., 1992 USA Haliotis kamtschatkana PAUL et al., 1977 Haliotis rufescens EBERT & HOUK, 1984 South Africa Haliotis midae SALES & BRIZT, 2001 Australia Haliotis rubra FLEMING & HONE, 1996 Haliotis roei KEESING & WELLS, 1989 Haliotis asinina COUNIHAN et al., 2001 New Zealand Haliotis iris HOOKER & CREESE, 1995 Haliotis australis MOSS, 1999 China Haliotis discus hannai NIE et al., 1996 Taiwan Haliotis diversicolor CHEN, 1984 Japan Haliotis discus discus KOJIMA, 1981 Haliotis discus hannai UKI & KIKUCHI, 1982 Haliotis discus UKI & KIKUCHI, 1984 Korea Haliotis discus hannai YOO, 1989; FAO, 1996 Thailand Haliotis asinina SINGHAGRAIWAN & SASAKI, 1991 Haliotis ovina and JARAYABHAND & PAPHAVASIT, 1996 Haliotis varia The Philippines Haliotis asinina CAPINPIN et al., 1998 Indonesia Haliotis asinina SETYONO, 2003

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15 cm

Shelter Meshed window

35 cm

30 cm

Figure 1. Schematic drawing of rectangular net cages used to grow out juvenile Haliotis asinina.

Wire

Steel frame

Meshed area

Shelter

Meshed window

40 cm

Figure 2. Schematic drawing of circular net cages used to grow out juvenile Haliotis asinina.

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Wire

Meshed window

14 cm

50 cm

Figure 3: Schematic drawing of tyre net cage used to grow out juvenile Haliotis asinina.

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