1 Introduction and History of Cage Culture Chua Thia Eng 1 and Elsie Tech 2 1 Partnerships in Environmental Management for the Seas of East Asia (PEMSEA), DENR Compound, Visayas Avenue, Quezon City, Philippines; 2 Asian Fisheries Society 25-A Mayaman Street, UP Village, Quezon City, Philippines History of Cage Culture Open sea activities, such as cage and pen culture, are viewed by many stakeholders in the industry as the aquaculture system of the millennium. Fish production from cages and pens (both in freshwater and marine environments) contributes significantly to total foodfish produced. Cage culture has made possible the large-scale production of commercial finfish and will probably be the most efficient and economical way of raising fish. Aquaculturists realize the need to limit further conversion of wetlands and man - groves into traditional aquaculture farms. We face a situation where even freshwater ecosystems have reached critical levels with respect to their carrying capacities. The depletion of ocean and coastal fishery resources in some areas has led to the development of marine cage culture. The earliest record of cage culture practices dates back to the late 1800s in Southeast Asia, particularly in the fresh - water lakes and river systems of Kampuchea (Coche, 1976; Pantulu, 1979; Beveridge, 1987). The fish cultured included snake - heads (Channa spp.), catfishes (Pangasius spp.) and gobies (Oxycleotris spp.). By 1995, more than 5000 fish farmers were engaged in cage culture in the Mekong river system around Phnom Penh (Thana, 1995). There were also reports of similar culture practices in Indonesia in the 1920s and 1940s (Hickling, 1962). Marine fish farming in cages traces its beginnings to the 1950s in Japan where fish farming research at the Fisheries Laboratory of the Kinki University led to the com- mercial culture of the yellowtail, Seriola quinqueradiata. Takashima and Arimoto (2000), however, traced back a history of 200 years where wooden farm net cages were being operated for anchovies or sardines or bait for skipjack. Similar cages were later used for yellowtail culture in Japan and developed into a significant industry as early as 1960. The cage culture of common carp (Cyprinus carpio) in lakes also started at this time (Kuronuma, 1968). Since the 1970s, Thailand has developed cage culture techniques for two important marine finfish: the seabream (Pagrus major) and grouper (Epinephelus spp.) (Coche, 1976). Chua and Teng (1978) pioneered the development of cage culture methods/designs for groupers in Malaysia, although large-scale cage farm - ing in marine waters really gained ground in the 1980s and in inland waters in the 1990s (Shariff and Nagaraj, 2000). Korea started growing a European variety of common carp and maintained yellowtail in holding cage enclosures in the late 1970s. By the end of 1980, cage culture of the olive flounder (Paralichthys olivacens) and black rockfish ©CAB International 2002. Diseases and Disorders of Finfish in Cage Culture (eds P.T.K. Woo, D.W. Bruno and L.H.S. Lim) 1 (Sebastes schlegeli) was established, and developed into a successful aquaculture industry in the 1990s (Kim, 2000). Cage culture of groupers (Epinephelus spp.) in the Philippines has been practised since the 1980s. Mariculture of milkfish in the 1990s led to the further growth and development of the industry (Marte et al., 2000). In Europe, cage culture of rainbow trout (Oncorhynchus mykiss) in fresh water began in the late 1950s and, in Norway, Atlantic salmon (Salmo salar) followed in the 1960s. More than 40% of its rainbow trout comes from freshwater cages (Beveridge, 1987). Salmonid culture is currently dominated by production from Norway, Scotland and Chile. Cage culture of fish was adopted in the USA in 1964 (Coche, 1976). Records show commercial production of channel catfish (Ictalurus punctatus) in freshwater cages (Collins, 1970a,b, 1972; Trotter, 1970; Bennet, 1971; Brett, 1974; Novotny, 1975). Cage culture in Africa, however, is still in its infant stage (ADB/NACA, 1998). In Central Africa, there was no real practical experience in cage culture before 1974. Very limited observations were recorded for Clarias lazera (de Kimpe and Micha, 1974). Semi-intensive rearing was done in Lake Victoria, Tanzania, using Nile tilapia (Tilapia zillii) (Ibrahim et al., 1974). Research initiatives on intensive production of commercial sized Tilapia nilotica were carried out in Lake Kossou, Ivory Coast (Coche, 1974, 1975; Shehadeh, 1974). Cook (1995) reported that it was only in the 1980s that the potential of aquaculture in South Africa gained grounds with respect to becoming a viable commercial industry. Freshwater aquaculture was limited to availability of water while mariculture had to rely on only 3000 km of coastlines (the majority of which did not have sheltered bays or lagoons). In the years that followed, efforts were geared towards improvement in the culture of tilapia and cage design (Coche, 1976). Currently many fish species have been cultivated in various designs and sizes of cages in Asia, Europe and other parts of the world (Table 1.1). Tilapia and carp pre- dominate in freshwater cage culture in Asia, while salmonids are commonly farmed in Europe and the Americas. 2 T.E. Chua and E. Tech Species cultured Country Reference Anguillidae Anguilla japonica (eel) Bagridae Mystus nemerus (mystid catfish) Chanidae Chanos chanos (milkfish) Channidae Channa macrocephalus Channa micropeltes (snakehead) Channa striatus Giant snakehead Characidae Colossoma macropomum (Amazonian fish tambaqui) Cichlidae Black tilapia Oreochromis mortimeri Oreochromis niloticus (Nile tilapia) China Malaysia Philippines Thailand Cambodia Vietnam Vietnam Malaysia Brazil Malaysia Zimbabwe Zimbabwe Bangladesh Malaysia Yuan (1991) Shariff and Nagaraj (2000) Guerrero (1996); Ramos (1996); Bagarinao (1998); Marte et al . (2000) Lin (1990) Thana (1995) Pantulu (1976); Thuoc (1995) Pantulu (1976); Thuoc (1995) Ang et al . (1988) Chellappa et al . (1995) Ang et al . (1988) Norberg and Stenstroem (1993) Norberg and Stenstroem (1993) Mazid (1995) Shariff and Nagaraj (2000) Table 1.1a. Major species of freshwater finfishes cultured in cages. Introduction and History of Cage Culture 3 Species cultured Country Reference Red tilapia Sarotherodon aureus Sarotherodon esculentus Sarotherodon galilaeus Sarotherodon mossambicus Sarotherodon mossambicus × S. honorum (hybrid) Sarotherodon niloticus Sarotherodon spilirus niger (tilapia) Tilapia Tilapia Tilapia Tilapia heudeloti Tilapia nilotica Tilapia niloticus Tilapia rendalli Tilapia zillii Clariidae Clarias gariepinus Clarias lazera (Nile catfish) Clarias macrocephalus (catfish) Cyprinidae Abramis brana (bream) Aristichthys nobilis (bighead carp) Philippines Thailand Egypt Malaysia USA El Salvador Puerto Rico USA Tanzania Nigeria Philippines Taiwan Guatemala USA Sri Lanka Ivory Coast Nigeria Kenya Philippines Brazil Dominican Republic Togo USA Sierra Leone Togo Dominican Republic Nigeria Colombia Zimbabwe Tanzania Togo Kenya Nigeria Vietnam South Africa Egypt Thailand Vietnam Russia Nepal Santiago and Arcilla (1993); Lopez (1995) Chiayvareesajja et al . (1990); Lin (1990) Ishak and Hassanen (1987) Ang et al . (1988) Schmittou (1969); Perry and Avault (1972) Bayne et al . (1976); Ramirez (1977); Sanchez (1978); Street (1978) Jordan and Pagan (1973); Miller and Ballantine (1974) Williams et al . (1974) Ibrahim et al . (1976) Konikoff (1975); Ita (1976) Guerrero (1975); IFP (1976); Pantastico and Baldia (1979) Maruyama and Ishida (1976) Bardach et al . (1972) Suffern et al . (1978) Anon. (1980); Muthukumarana and Wcerakoon (1987) Coche (1975, 1976, 1977, 1978); Campbell (1976); Shehadeh (1976); de Kimpe (1978); Amoikon (1987) Konikoff (1975); Campbell (1987) Haller (1974) PCARRD (1981); Aragon et al . (1985); Guerrero (1985, 1996) FAO (1977) Olivo (1987) Issifou and Amegavie (1987) McGinty (1991) Iscandari (1987) Issifou and Amegavie (1987) Olivo (1987) Ali (1987) Patino (1976); McLarney (1978); Popma (1978) Norberg and Stenstroem (1993) Ibrahim et al . (1974) Issifou and Amegavie (1987) Haller (1974) Konikoff (1975); Campbell (1987) Tuan and Hambrey (2000) Hoffman and Prinsloo (1992) Ishak (1987) Lin (1990) Tuan and Hambrey (2000) Ziliukiene (1994) Swar and Pradhan (1992); Pradhan and Pantha (1995) Continued 4 T.E. Chua and E. Tech Species cultured Country Reference Carps Carps Carps Cirrhinus microbis Cirrhinus sp. Ctenopharyngodon idella (grass carp) Cyprinids Cyprinus carpio (common carp) (mirror carp) Hypophthalmichthys molitrix (silver carp) (Javanese carp) Leptobarbus hoeveni (slender carp/sultan fish) Nile carp River carp Eleotridae Goby Oxyeleotris marmoratus (sand goby) Ictaluridae Ictalurus punctatus (Channel catfish) Moronidae Morone chryops × M. saxatilis (sunshine bass) Osphronemidae Osphronemus gourami (giant gouramy) Malaysia Philippines Sri Lanka India Indonesia Iran Cambodia Cambodia Malaysia Nepal Sri Lanka Vietnam Egypt Netherlands India Philippines Poland Russia Nepal Indonesia Korea Egypt Israel Turkey Nepal Egypt India Malaysia Vietnam Malaysia Indonesia Egypt Malaysia Malaysia Thailand Vietnam USA USA Indonesia Malaysia Ang et al . (1988) Fermin (1990); Marte et al . (2000) Muthukumarana and Weerakoon (1987) Basavaraja (1994) Costa-Pierce and Effendi (1988) Matinfar and Nikouyan (1995) Thana (1995) Thana (1995) Ang et al . (1988) Pradhan and Pantha (1995) Muthukumarana and Weerakoon (1987) Lovatelli (1997) Siemelink et al . (1982); Ishak (1987) Huisman (1979) Bandyopadhyay et al . (1991) Lopez (1995) Filipiak (1991); Mamcarz (1992) Evtushenko (1994) Pradhan and Pantha (1995) Costa-Pierce and Roem (1990); Zainal et al . (1990) Kim et al . (1992) Hamza (1996) Viola and Lahav (1991); Wolhfarth and Moav (1991) Erden (1987) Swar and Pradhan (1992); Pradhan and Pantha (1995) Hamza (1996) Sivakami and Ayyappan (1991) Ang et al . (1988) Thuoc (1995); Lovatelli (1997) Shariff and Nagaraj (2000) Dahril and Ahmad (1990) Hamza (1996) Ang et al . (1988) Ang et al . (1988) Menasveta (2000) Lovatelli (1997) Schmittou (1969); Perry and Avault (1972); Collins and Delmendo (1979); Parker (1988); Masser and Duarte (1992); Burtle and Newton (1993); Webster et al . (1994) Kelly and Kohler, 1996; Pagan (1970); Suwanasart (1971); Pagan-Font (1975) Ang et al . (1988) Ang et al . (1988) Table 1.1a. Continued . Introduction and History of Cage Culture 5 Species cultured Country Reference Pangasiidae Pangasius bocourti (yellow catfish) Pangasius conchophilis Pangasius hypophthalmus (catfish) Pangasius lardnaudi Pangasius micronemus Pangasius nasutus (catfish) Pangasius pangasius (river catfish) Pangasius sutchii (striped catfish) River catfish Percidae Perca fluviatilis (perch) Salmonidae Coregonus Coregonus albula (vendace) Coregonus lavaretus (Baltic whitefish) (whitefish) Coregonus peled (peled) Oncorhynchus mykiss (rainbow trout) Salmo salar (Atlantic salmon) Salmo trutta (broom trout) Stenodus (whitefish) Sciaenidae Sciaenops ocellatus (red drum or red fish) Siluridae Silurus glanis (sheat fish) Esox lucius (pike) Puntius gonionotus (minnows) Puntius schwanenfeldii (tinfoil barb) (minnows) Puntius spp. Vietnam Vietnam Cambodia Vietnam Cambodia Cambodia Vietnam Vietnam Thailand Malaysia Malaysia France Germany Poland Finland Germany Russia France Canada Bolivia Canada Denmark Iran Sweden Switzerland Norway USA Indonesia Northern Europe Ecuador Israel Panama Poland Yugoslavia Russia Bangladesh Vietnam Indonesia Vietnam Cambodia Lovatelli (1997) Lovatelli (1997); Tuan and Hambrey (2000) Thana (1995) Tuan and Hambrey (2000) Thana (1995) Thana (1995) Tuan and Hambrey (2000) Thuoc (1995) Menasveta (2000) Shariff and Nagaraj (2000) Ang et al . (1988) Tamazouzt et al . (1993) Marciak (1979) Mamcarz (1984) Mamcarz (1984) Schultz et al . (1993) Jager and Nellen (1981) Champigneulle and Rojas-Beltran (1990) Mamcarz and Kozlowski (1992) Menton (1991) Srivastava et al . (1991); Cornel and Whoriskey (1993) Torrissen et al . (1995) Matinfar and Nikouyan (1995) Alanaerae (1992) Mamcarz and Szczerbowski (1984) Torrissen et al . (1995) Rottiers (1994) Goeltenboth and Krisyanto (1994) Bronisz (1979) Benetti et al . (1995) Kissil (1996) Garces (1992) Mamcarz and Worniallo (1985) Stevic et al . (1993) Ziliukiene (1994) Mazid (1995) Thuoc (1995) Christensen (1993) Thuoc (1995) Thana (1995) 6 T.E. Chua and E. Tech Species cultured Country Reference Chanidae Chanos chanos (milkfish) Cichlidae Oreochromis urolepsis hornorum × O. mossambicus male (Florida red tilapia) Moronidae Morone chryops × M. saxatilis (sunshine bass) Pisodonophis Pisodonophis boro (brackishwater eel) Salmonidae Coregonus lavaretus (Baltic whitefish) Oncorhynchus mason rhodurus (Amago salmon) Salmo salar (Atlantic salmon) Philippines USA USA Vietnam Germany Yugoslavia USA Guerrero (1996); Ramos (1996); Bagarinao (1998); Marte et al . (2000) Rust et al . (1991) Pagan (1970); Suwanasart (1971); Pagan-Font (1975); Kelly and Kohler (1996) Lovatelli (1997) Schultz et al . (1993) Teskeredzic and Teskeredzic (1990) Rottiers (1994) Table 1.1b. Major species of brackish water finfishes cultured in cages. Species cultured Country Reference Carangidae Longirostrum/Caranx delicatissimus (striped jack) Seriola dumerili Seriola magatlana (Pacific yellowtail) Seriola purpurescens (amberjack) Seriola quinqueradiata (yellowtail) Sturgeon Sturgeon (beluga × sterlet, ‘bestir’) Trachinotus carolinus (pompano) Trachinotus oaitensis (pompano) Trachinotus teraia Centropomidae Centropomus nigrescens (snook) Lates calcarifer (seabass) Japan Taiwan Ecuador Hong Kong Japan China Korea Iran Russia USA Ecuador France Ecuador China Hong Kong Indonesia Malaysia Philippines Singapore Thailand Vietnam Australia Watanabe (1988a,b) Su et al . (2000) Benetti et al . (1995) Wong (1995) Fujiya (1976); Mitani (1979); Kafuku and Ikenoue (1983); Shepherd and Bromage (1988); Fukumoto (1989); Watanabe et al . (1996) Lin (1997) Shepherd and Bromage (1988); Fukumoto (1989); Jeon et al . (1992); Kim (1995) Matinfar and Nikouyan (1995) Romanycheva and Salnikov (1979) Smith (1973) Benetti et al . (1995) Trebaol (1991) Benetti et al . (1995) Yongjia et al . (1996) Wong (1995) Sakaras (1982); Kungvankij (1987b) Singh (1991); Hannafi et al . (1995) Toledo et al . (1991); Fermin et al . (1993); Alcantara et al . (1995); Lopez (1995) Anon. (1986); Cheong and Lee (1987) Sakaras (1984); Kungvankij (1987a); Tookwinas (1990b); Chaitanawisuti and Piyatiratitivorakul (1994a) Lovatelli (1997) Barlow et al . (1995); Rimmer (1998) Table 1.1c. Major species of marine finfishes cultured in cages. Introduction and History of Cage Culture 7 Species cultured Country Reference Characidae Piaractus mesopotamicus (pacu) Cichlidae Oreochromis spilirus (tilapia) Oreochromis urolepsis hornorum × O. mossambicus male (Florida red tilapia) Cyprinidae Barbus gonionotus (silver barb) Cirrhina (rohu) Gadidae Cod Gadus morhua (Atlantic cod) Lutjanidae Lutjanus argentimaculatus (red snapper) Lutjanus erythropeterus Lutjanus johni (golden snapper) Lutjanus russelli (Russell’s snapper) Lutjanus sebae Lutjanus stellatus Pagrus major (Japanese red seabream/red seabream) Moronidae Dicentrarchus labrax (seabass) (European seabass) Oplegnathidae Oplegnathus fasciatus (rock bream) Paralichthyidae Paralichthys olivaceus (bastard halibut/flounder) (olive flounder) Percichthyidae Lateolabrax japonicus (Japanese seabass) Percidae Stizostedion lucioperca (wild zander) Pleuronectidae Hippoglossus hippoglossus (Atlantic halibut) Brazil Kuwait USA Vietnam Nepal Norway Canada China Malaysia Philippines Singapore Thailand Taiwan Malaysia Singapore China Hong Kong Malaysia Thailand Taiwan Israel Japan Korea Taiwan Egypt Italy Israel Korea Japan Japan Japan Korea Korea Korea Finland UK Ferraz de Lima et al . (1992) Cruz and Ridha (1990b) Rust et al . (1991) Lovatelli (1997) Pradhan and Pantha (1995) Kaspruk and Tvejte (1994); Hjelt (2000) Jones and Iwama (1990) Yongjia et al . (1996) Ali (1987); Hannafi et al . (1995) Emata (1996) Cheong (1988) Doi and Singhagraiwan (1993); Chaitanawisuti and Piyatiratitivorakul (1994b) Su et al . (2000) Hannafi et al . (1995) Lee (1982); Anon. (1986) Yongjia et al . (1996) Wong (1995) Rahim (1982) Tanomkiat (1982) Su et al . (2000) Kissil (1996) Fukumoto (1989 Kim (1995) Su et al . (2000) Ishak and Hassanen (1987) Barbato et al . (1991) Kissil (1996) Kim (1995) Watanabe (1988a,b) Hiraishi et al . (1995) Kikuchi et al . (1993) Kim (1995) Jeon et al . (1992) Kim (1995) Salminen et al . (1992) Martinez-Cordero et al . (1994) Continued 8 T.E. Chua and E. Tech Species cultured Country Reference Limanda herzentein (brown sole) Limanda punctatissima (longsnout flounder) Rachycentridae Rachycentron canadum Salmonidae Caspian salmon Onchorynchus kisutch (Coho salmon) Oncorhynchus mason rhodurus (Amago salmon) Oncorhynchus mykiss (rainbow trout) Oncorhynchus tshavytocha (Chinook salmon) Prosopium Salmo salar (Atlantic salmon) Salmo trutta (broom trout) Salvelinus alpinus (Arctic charr) Sciaenidae Cynoscion stolzmanni (corvina) Ophicephalus sp. (serpent head) Scianops teraia (Western African pompano) Sebastidae Sebastes schlegeli (Schlegel’s black rock fish) Scophthalmidae Scophthalmus maximus (turbot) Serranidae Cephalopholis mimata Cephalopholis pachycenteron Epinephelus akaara Epinephelus alwaora (grouper) Epinephelus amblycephalus Epinephelus areolatus (spotted grouper) Epinephelus bleeker Epinephelus bleekeri Epinephelus coioides Epinephelus fario Epinephelus fuscoguttatus Korea Japan Taiwan Iran Chile Yugoslavia Canada Canada Germany Canada Scotland Norway USA France Norway Ecuador Thailand France China Korea France Vietnam Philippines Hong Kong Japan Vietnam China China Taiwan Hong Kong Philippines Vietnam Philippines Taiwan Vietnam Sri Lanka Singapore Indonesia Kim (1995) Hiraishi et al . (1995) Su et al . (2000) Matinfar and Nikouyan (1995) Jelvez-Flores (1992) Teskeredzic and Teskeredzic (1990) Srivastava et al . (1991); Cornel and Whoriskey (1993) Jones and Iwama (1990) Marciak (1979) Egan and Kenney (1990); Menton and Allen (1991); Duston and Saunders (1994) Glen (1974); Went (1980); Worniallo and Mamcarz (1985); Sangster and Munro (1991); Smith et al . (1993) Kraakenes et al . (1991) Rottiers (1994) Arzel et al . (1993) Torrissen et al . (1995) Benetti et al . (1995) Menasveta (2000) Trebaol (1991) Liu et al . (1991) Kim (1995) Vigneulle and Laurencin (1995) Tuan and Hambrey (2000) Sayong (1981) Chao and Lim (1991); Wong (1995) Ukawa et al . (1966); Chao and Lim (1991) Tuan and Hambrey (2000) Chao and Lim (1991); Wong (1995) Chao and Lim (1991) Maruyama and Ishida (1976) Wong (1995) Kohno et al . (1988) Tuan and Hambrey (2000) Quinitio et al . (1997) Su et al . (2000) Tuan and Hambrey (2000) Chao and Lim (1991) Lim et al . (1990); Chao and Lim (1991) Chao and Lim (1991) Table 1.1c. Continued . Introduction and History of Cage Culture 9 Species cultured Country Reference Epinephelus hexagonatus Epinephelus macrospilos Epinephelus malabaricus Epinephelus merra Epinephelus microdon Epinephelus moara (kelp bass) Epinephelus salmonoides Epinephelus sexfaciatus Epinephelus spp. Epinephelus suillus Epinephelus summana Epinephelus tauvina (green grouper, estuarine grouper) Siganidae Siganus canaliculatus (rabbit fish) Siganus guttatus (siganid) Sillaginidae Sillago sihama (sand whiting) Sparidae Acanthopagrus schlegeli (black seabream) Chrysophrys major (red pargo) Mylio latus (yellow finned seabream) Puntazzo puntazzo (sheepshead bream) Rhabdosargus sarba (goldlined seabream) Sparrus aurata (gilthead seabream) Sparrus macrocephalus Tetraodontidae Takifugu rubripes (tiger puffer) Japan Philippines India Philippines China Philippines Philippines Vietnam Japan Japan China Philippines Sri Lanka Japan Malaysia Philippines Vietnam Malaysia Philippines Singapore Thailand Philippines Taiwan Philippines Hong Kong India Indonesia Malaysia Philippines Singapore Singapore Kuwait Indonesia Philippines Vietnam India Korea China Hong Kong Hong Kong Israel Hong Kong Israel Israel China Japan Korea Chao and Lim (1991) PCARRD (1986); Quinitio and Toledo (1991) Hamsa and Kasim (1992) PCARRD (1986); Quinitio and Toledo (1991) Yongjia et al . (1996) Kohno et al . (1988) Sayong (1981) Tuan and Hambrey (2000) Chao and Lim (1991) Chao and Lim (1991) Yongjia et al . (1996) Kungvankij et al . (1986) Chao and Lim (1991) Chao and Lim (1991) Chua (1979); Chua and Teng (1979, 1980) Kohno et al . (1988) Tuan and Hambrey (2000) Leong (1998) Quinitio and Toledo (1991) Anon. (1986) Tookwinas (1990a); Menasveta (2000) Toledo et al . (1993) Maruyama and Ishida (1976) Sayong (1981) Wong (1995) Hamsa and Kasim (1992) Lanjumin (1982) Chua and Teng (1978); Rahim (1982); Ali (1987) Kohno et al . (1988); Lopez (1995) Cheong and Lee (1987) Chao and Lim (1991) Hussain et al . (1975); Chao and Lim (1991) Tacon et al . (1990) Lopez (1995); Soriano et al . (1995) Lovatelli (1997) James et al . (1985) Kim (1995) Yongjia et al . (1996) Wong (1995) Wong (1995) Kissil (1996) Wong (1995) Kissil (1996) Porter et al . (1991) Yongjia et al . (1996) Shepherd and Bromage (1988) Moon et al . (1993); Kim (1995) The rapid growth of the industry in most countries may be attributed to: (i) suitable offshore sites for cage culture; (ii) well established breeding techniques that yield a sufficient quantity of various marine and freshwater fish juveniles; (iii) availability of supporting industries, such as feed and fish - ing net manufacturers, and fish processors and packers; (iv) strong research and devel - opment initiatives from institutions, govern - ment and universities; and (v) the private sector ensuring refinement and improve - ment of techniques/culture systems, thereby further developing the industry. With the experiences seen in salmon farming, seabream (Sparus auratus) and sea- bass (Dicentrarchus labrax) cage culture activities started to move toward offshore areas. The lack or non-availability of sheltered sites in many regions because of varied coastline configurations, the build-up of organic matter in closed bays due to poor water exchange, and use conflicts between industries and tourism for sea water were the main reasons for such a shift (Lisac, 1991). Some of the offshore cage systems that later developed include: Dunlop Tempest I (Fearn, 1991); ‘SADCO’ cages (Muravjev et al., 1993); Ocean Spar (Loverich and Croker, 1993); Farmocean system (Gunnarson, 1993); Seacon system (Lien, 2000); and Bridgeton Hi-Seas (Gunnarson, 1993; Lien, 2000). Muir (1998) considered the following criteria important for success in offshore cage culture: (i) location (> 2 km from shore); (ii) environment (average waves > 5 m, regularly 2–3 m oceanic swells, variable wind periods); (iii) access (about 80% of the time when cages are accessible to working staff); and (iv) operation (remote; with automated feeding devices and long- distance monitoring). Advantages and Limitations of Cage Culture In general, cage culture practices have numerous advantages over other culture systems. By integrating the cage culture system into the aquatic ecosystem the carry - ing capacity per unit area is optimized because the free flow of current brings in fresh water and removes metabolic wastes, excess feed and faecal matter (Beveridge, 1983). Operationally, this has a number of advantages. Some cage designs, especially those used in inshore cultures, are rela - tively easy to construct with minimal skilled labour, and cages utilize minimal physical facilities and space. Economically, cage culture is a low-input farming practice with high economic return. However, cage culture is a high risk and labour-intensive operation. The practice is vulnerable to natural hazards (strong tides, storms and typhoons) and can be affected by deteriorat - ing water quality attributed to chronic pollution from oil and chemical spills from oil tankers and cargo vessels (Tabira, 1980; Nose, 1985). In addition, poaching and vandalism are reported by cage farmers. The advantages and limitations of cage culture are summarized in Table 1.2. In view of the high production attain- able in cage culture system and the presence of large sheltered coastal waters in many countries, marine cage farming can play a significant role in increasing fish production. Cage culture systems vary in terms of farm size and intensity of operation. Floating cages, for instance, in Korea can reach yields exceeding 500 t ha −1 (ADB/NACA, 1998). Cage Design Cage design is determined by conditions in the culture site, as well as the ecological requirements and behaviour of the target species for culture. Each design is site- specific and knowledge of the topography, wind force, wind direction, prevalence of storms, monsoons, wave load, current velocity and water depths are important parameters for consideration. In designing cages, it is also important to consider the rate of biofouling and the species composi - tion of the marine fauna in and around the potential site (Chua, 1982). A checklist of 10 T.E. Chua and E. Tech