Tài liệu Introduction and History of Cage Culture docx

Fish production from cages and pens both in freshwater and marine environments contributes significantly to total foodfish produced.. Marine fish farming in cages traces its beginnings t

1 Introduction and History of Cage Culture

Chua Thia Eng 1 and Elsie Tech 2

1Partnerships in Environmental Management for the Seas of East Asia (PEMSEA), DENR Compound, Visayas Avenue, Quezon City, Philippines;2Asian 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 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

farm-of 1980, cage culture farm-of the olive flounder

(Paralichthys olivacens) and black rockfish

©CAB International 2002 Diseases and Disorders of Finfish in Cage Culture

(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.

ThailandCambodiaVietnamVietnamMalaysiaBrazil

MalaysiaZimbabweZimbabweBangladeshMalaysia

Yuan (1991)Shariff and Nagaraj (2000)Guerrero (1996); Ramos (1996); Bagarinao (1998);Marteet al (2000)

Lin (1990)Thana (1995)Pantulu (1976); Thuoc (1995)Pantulu (1976); Thuoc (1995)Anget al (1988)

Chellappaet al (1995)

Anget 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

Clarias lazera(Nile catfish)

Clarias macrocephalus(catfish)

Cyprinidae

Abramis brana(bream)

Aristichthys nobilis(bighead carp)

PhilippinesThailandEgyptMalaysiaUSA

El SalvadorPuerto RicoUSATanzaniaNigeriaPhilippinesTaiwanGuatemalaUSASri LankaIvory Coast

NigeriaKenyaPhilippinesBrazilDominicanRepublicTogoUSASierra LeoneTogoDominicanRepublicNigeriaColombiaZimbabweTanzaniaTogoKenyaNigeriaVietnamSouth AfricaEgyptThailandVietnamRussiaNepal

Santiago and Arcilla (1993); Lopez (1995)Chiayvareesajjaet al (1990); Lin (1990)Ishak and Hassanen (1987)

Anget al (1988)Schmittou (1969); Perry and Avault (1972)Bayneet al (1976); Ramirez (1977); Sanchez(1978); Street (1978)

Jordan and Pagan (1973); Miller and Ballantine(1974)

Williamset al (1974)Ibrahimet al (1976)Konikoff (1975); Ita (1976)Guerrero (1975); IFP (1976); Pantastico and Baldia(1979)

Maruyama and Ishida (1976)Bardachet al (1972)Suffernet 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); Aragonet 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)

Ibrahimet 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

USA

IndonesiaMalaysia

Anget al (1988)Fermin (1990); Marteet al (2000)Muthukumarana and Weerakoon (1987)Basavaraja (1994)

Costa-Pierce and Effendi (1988)Matinfar and Nikouyan (1995)Thana (1995)

Thana (1995)Anget al (1988)Pradhan and Pantha (1995)Muthukumarana and Weerakoon (1987)Lovatelli (1997)

Siemelinket al (1982); Ishak (1987)Huisman (1979)

Bandyopadhyayet al (1991)Lopez (1995)

Filipiak (1991); Mamcarz (1992)Evtushenko (1994)

Pradhan and Pantha (1995)Costa-Pierce and Roem (1990); Zainalet al.(1990)

Kimet 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)Anget al (1988)

Thuoc (1995); Lovatelli (1997)Shariff and Nagaraj (2000)Dahril and Ahmad (1990)Hamza (1996)

Anget al (1988)Anget al (1988)Menasveta (2000)Lovatelli (1997)Schmittou (1969); Perry and Avault (1972); Collinsand Delmendo (1979); Parker (1988); Masser andDuarte (1992); Burtle and Newton (1993); Webster

et al (1994)Kelly and Kohler, 1996; Pagan (1970); Suwanasart(1971); Pagan-Font (1975)

Anget al (1988)Anget al (1988)

Table 1.1a. Continued

Introduction and History of Cage Culture 5

Pangasius nasutus(catfish)

Pangasius pangasius(river

Coregonus albula(vendace)

Coregonus lavaretus(Baltic

Salmo salar(Atlantic salmon)

Salmo trutta(broom trout)

Silurus glanis(sheat fish)

Esox lucius(pike)

Puntius gonionotus(minnows)

Puntius schwanenfeldii(tinfoil barb)

(minnows)

Puntiusspp

VietnamVietnamCambodiaVietnamCambodiaCambodiaVietnamVietnamThailandMalaysiaMalaysiaFranceGermanyPolandFinlandGermanyRussiaFranceCanadaBoliviaCanadaDenmarkIranSwedenSwitzerlandNorwayUSAIndonesiaNorthernEuropeEcuadorIsraelPanamaPolandYugoslaviaRussiaBangladeshVietnamIndonesiaVietnamCambodia

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)Anget al (1988)

Tamazouztet al (1993)Marciak (1979)Mamcarz (1984)Mamcarz (1984)Schultzet al (1993)Jager and Nellen (1981)Champigneulle and Rojas-Beltran (1990)Mamcarz and Kozlowski (1992)Menton (1991)

Srivastavaet al (1991); Cornel and Whoriskey(1993)

Torrissenet al (1995)Matinfar and Nikouyan (1995)Alanaerae (1992)

Mamcarz and Szczerbowski (1984)Torrissenet al (1995)

Rottiers (1994)Goeltenboth and Krisyanto (1994)Bronisz (1979)

Benettiet al (1995)Kissil (1996)Garces (1992)Mamcarz and Worniallo (1985)Stevicet al (1993)

Ziliukiene (1994)Mazid (1995)Thuoc (1995)Christensen (1993)Thuoc (1995)Thana (1995)

6 T.E Chua and E Tech

Chanidae

Chanos chanos(milkfish)

Cichlidae

Oreochromis urolepsis hornorum×O

mossambicusmale (Florida red tilapia)

Coregonus lavaretus(Baltic whitefish)

Oncorhynchus mason rhodurus(Amago

Guerrero (1996); Ramos (1996); Bagarinao(1998); Marteet al (2000)

Table 1.1b. Major species of brackish water finfishes cultured in cages

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)

JapanTaiwanEcuadorHong KongJapan

ChinaKoreaIranRussiaUSAEcuadorFranceEcuadorChinaHong KongIndonesiaMalaysiaPhilippinesSingaporeThailand

VietnamAustralia

Watanabe (1988a,b)

Suet al (2000)Benettiet al (1995)Wong (1995)Fujiya (1976); Mitani (1979); Kafuku andIkenoue (1983); Shepherd and Bromage (1988);Fukumoto (1989); Watanabeet al (1996)Lin (1997)

Shepherd and Bromage (1988); Fukumoto(1989); Jeonet al (1992); Kim (1995)Matinfar and Nikouyan (1995)Romanycheva and Salnikov (1979)Smith (1973)

Benettiet al (1995)Trebaol (1991)Benettiet al (1995)Yongjiaet al (1996)Wong (1995)Sakaras (1982); Kungvankij (1987b)Singh (1991); Hannafiet al (1995)Toledoet al (1991); Ferminet al (1993);Alcantaraet al (1995); Lopez (1995)Anon (1986); Cheong and Lee (1987)Sakaras (1984); Kungvankij (1987a); Tookwinas(1990b); Chaitanawisuti and Piyatiratitivorakul(1994a)

Lovatelli (1997)Barlowet al (1995); Rimmer (1998)

Table 1.1c. Major species of marine finfishes cultured in cages

Introduction and History of Cage Culture 7

Characidae

Piaractus mesopotamicus(pacu)

Cichlidae

Oreochromis spilirus(tilapia)

Oreochromis urolepsis hornorum×O

mossambicusmale (Florida red tilapia)

Lutjanus johni(golden snapper)

Lutjanus russelli(Russell’s snapper)

VietnamNepalNorwayCanadaChinaMalaysiaPhilippinesSingaporeThailandTaiwanMalaysiaSingaporeChinaHong KongMalaysiaThailandTaiwanIsraelJapanKoreaTaiwanEgyptItalyIsraelKoreaJapanJapanJapanKoreaKoreaKorea

FinlandUK

Ferraz de Limaet al (1992)Cruz and Ridha (1990b)Rustet al (1991)

Lovatelli (1997)Pradhan and Pantha (1995)Kaspruk and Tvejte (1994); Hjelt (2000)Jones and Iwama (1990)

Yongjiaet al (1996)Ali (1987); Hannafiet al (1995)Emata (1996)

Cheong (1988)Doi and Singhagraiwan (1993); Chaitanawisutiand Piyatiratitivorakul (1994b)

Suet al (2000)Hannafiet al (1995)Lee (1982); Anon (1986)Yongjiaet al (1996)Wong (1995)Rahim (1982)Tanomkiat (1982)

Suet al (2000)Kissil (1996)Fukumoto (1989Kim (1995)

Suet al (2000)Ishak and Hassanen (1987)Barbatoet al (1991)Kissil (1996)Kim (1995)Watanabe (1988a,b)Hiraishiet al (1995)Kikuchiet al (1993)Kim (1995)Jeonet al (1992)Kim (1995)

Salminenet al (1992)Martinez-Corderoet al (1994)

Continued

8 T.E Chua and E Tech

Limanda herzentein(brown sole)

Limanda punctatissima(longsnout

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)

Ophicephalussp (serpent head)

Scianops teraia(Western African

pompano)

Sebastidae

Sebastes schlegeli(Schlegel’s

black rock fish)

TaiwanIranChileYugoslaviaCanadaCanadaGermanyCanadaScotland

NorwayUSAFranceNorwayEcuadorThailandFrance

ChinaKoreaFranceVietnamPhilippinesHong KongJapanVietnamChinaChinaTaiwanHong KongPhilippinesVietnamPhilippinesTaiwanVietnamSri LankaSingaporeIndonesia

Kim (1995)Hiraishiet al (1995)

Suet al (2000)Matinfar and Nikouyan (1995)Jelvez-Flores (1992)Teskeredzic and Teskeredzic (1990)Srivastavaet 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 andMamcarz (1985); Sangster and Munro (1991);Smithet al (1993)

Kraakeneset al (1991)Rottiers (1994)Arzelet al (1993)Torrissenet al (1995)Benettiet al (1995)Menasveta (2000)Trebaol (1991)

Liuet al (1991)Kim (1995)Vigneulle and Laurencin (1995)Tuan and Hambrey (2000)Sayong (1981)

Chao and Lim (1991); Wong (1995)Ukawaet 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)

Kohnoet al (1988)Tuan and Hambrey (2000)Quinitioet al (1997)

Suet al (2000)Tuan and Hambrey (2000)Chao and Lim (1991)Limet al (1990); Chao and Lim (1991)Chao and Lim (1991)

Table 1.1c. Continued

Introduction and History of Cage Culture 9

Siganus canaliculatus(rabbit fish)

Siganus guttatus(siganid)

Mylio latus(yellow finned seabream)

Puntazzo puntazzo(sheepshead bream)

Rhabdosargus sarba(goldlined

Chao and Lim (1991)PCARRD (1986); Quinitio and Toledo (1991)Hamsa and Kasim (1992)

PCARRD (1986); Quinitio and Toledo (1991)Yongjiaet al (1996)

Kohnoet al (1988)Sayong (1981)Tuan and Hambrey (2000)Chao and Lim (1991)Chao and Lim (1991)Yongjiaet al (1996)Kungvankijet al (1986)Chao and Lim (1991)Chao and Lim (1991)Chua (1979); Chua and Teng (1979, 1980)Kohnoet al (1988)

Tuan and Hambrey (2000)Leong (1998)

Quinitio and Toledo (1991)Anon (1986)

Tookwinas (1990a); Menasveta (2000)Toledoet al (1993)

Maruyama and Ishida (1976)Sayong (1981)

Wong (1995)Hamsa and Kasim (1992)Lanjumin (1982)Chua and Teng (1978); Rahim (1982); Ali (1987)Kohnoet al (1988); Lopez (1995)

Cheong and Lee (1987)Chao and Lim (1991)Hussainet al (1975); Chao and Lim (1991)Taconet al (1990)

Lopez (1995); Sorianoet al (1995)Lovatelli (1997)

Jameset al (1985)Kim (1995)Yongjiaet al (1996)Wong (1995)Wong (1995)Kissil (1996)Wong (1995)Kissil (1996)Porteret al (1991)Yongjiaet al (1996)Shepherd and Bromage (1988)Moonet 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 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.

carry-In view of the high production able in cage culture system and the presence

attain-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

fish species popularly cultured in Asia with

cage and culture specifications is provided

in Table 1.3.

Types of cages

A fish cage is usually made up of netting

with an opening at the surface to facilitate

feeding, removal of debris and dead fish,

and for harvesting The netcage system

consists of a netcage proper and the frame,

which supports the nets The frame is

normally kept afloat by buoys, usually

metal (or traditionally plastic drums), and

held in position by anchors Cages may be

classified as follows.

Fixed

A stationary cage is fastened to a fixed

bamboo or wooden pole at its corners It

consists of a net bag supported by posts driven into the bottom of a lake or river It is traditionally used in tropical countries like the Philippines for raising fish fingerlings.

It is inexpensive and simple to build This type of cage is normally restricted to shal- low areas with suitable substrates usually in freshwater systems.

Floating

A floating cage consists of a floating unit from which a single cage or a battery of netcages is suspended Floating cages are widely used for fish rearing in both fresh and coastal waters They are less restrictive

in terms of site selection compared with the stationary fixed types Surface floating cages are used in lakes, protected bays and lagoons, sheltered coves and inland seas The surface-floating unit consists of floats, framework and netcage Most floating cages

Maximizes use of available water resources

Reduces pressure on land resources

Combines several types of culture within one water

body; treatments and harvests independent

Ease of movement and relocation of cages

Intensification of fish production (high densities and

optimum feeding result in improved growth rates,

reducing rearing period)

Optimum utilization of artificial food improves food

conversion efficiencies

Easy control of competitors and predators

Ease of daily observation of stocks for better

management and early detection and treatment of

parasites and diseases

Reduces fish handling and mortalities

Easy fish harvest

Storage and transport of live fish facilitated

Initial investment is relatively small

Locations restricted to sheltered areasRequires back-up food store, hatchery andprocessing facilities

Needs adequate water exchange to removemetabolites and maintain high dissolved oxygenlevels; rapid fouling of cage walls requires frequentcleaning

Absolute dependence on artificial feeding unless insewage ponds; high-quality balanced rationsessential; feed losses possible through cage wallsSometimes important interference from the naturalfish population, i.e small fish enter cages andcompete for food

Natural fish populations act as a potential reservoir

of disease and parasites, and the likelihood ofspreading disease by introducing new culturedstocks is increased

Increased difficulties of disease and parasitetreatment

Risks of theft are increasedAmortization of capital investment may be shortIncreased labour costs for handling, stocking,feeding and maintenance

Table 1.2. Advantages and limitations of cage fish culture technique

Cylindrical floating netcage, 2 m diameter

× 2 m depth (6 m3); wood, bamboo,polythene and 200 l plastic drums for floatsBox-shaped floating netcage, 5 × 5 × 3 m;

wood and plastic drums

Rectangular broodstock floating netcage

4 × 4 × 3 m, installed with a hapa net of thesame dimension with mesh size of0.4–0.6 mm as egg collector; made ofbamboo, wood and 200 l plastic drumsCircular or rectangular broodstock floatingnetcages, 4 × 4 × 3 m or 10 × 10 × 2 m nylonmesh of size 4–8 cm

2 × 2 × 1.5 m or 10 × 5 × 1.5 m floatingnetcage

production about 5–7 daysStocking density is 40 fish m−3of size 18 cm; feeding with trashfish, once daily; 9 months culture period, 95.4% survival;

production of 490 g per fishStocking density is 44 fish m−3of size 80–100 g; feeding withtrash fish, cooked rice bran and aquatic vegetation, with FCR

of 4.5:1; 6–7 months of culture, 90% survival; production of

600 g per fishStocking density is 60–80 fish per cage, sex ratio is 13–28female:male fish; feeding with trash fish daily at 3–5% of bodyweight; culture period of 4 years; fish matured and naturallyspawned; also demonstrates an efficient, simple and cheapegg collector (116 million eggs in one breeding season)Stocking density is 1 fish m−3, sex ratio of 1:1 female:male fish;

feeding with trash fish and commercial bait fish (the pilchard

Sardinops neopilchardus) and vitamin supplementStocking density is 100 kg m−2of size 15 cm; feeding withfloating pellets twice daily (warm months) or once daily (winter)

to satiation, with FCR of 1.6–1.8:1; 8 months to 2 years cultureperiod; production of 350–600 g to 2–3 kg per fish

Stocking density is 15–25 fish m−3of size 2–3 inches; feedingwith trash fish once daily; 6–8 months of culture; production of500–600 g per fish

Stocked with juveniles; feeding with trash fish at 5% of bodyweight twice daily, with FCR of 3.6:1; 4 months culture period;

growth rate of 4 g per dayStocking density of 12–300 fish m−3; feeding fresh trash fishtwice daily, with FCR of 4–10:1; 12 months culture period;

production of 1 kg per fish, 80–95% survival

Philippines (Ramos,1996; Bagarinao, 1998)

Thailand (Chaitanawisutiand Piyatiratitivorakul,1994a)

Singapore (Anon.,1986)

Philippines (Toledoet al.,1991)

Australia (Rimmer,1998)

Australia (Barlowet al.,1995)

Malaysia (Singh, 1991)

Philippines (Alcantara

et al., 1995)Thailand (Tookwinas,1990b)

Table 1.3. Fish species and culture specifics of fish in Asia and Australia (From Buendia, 1998)

Introduction and History of Cage Culture

5 × 5 × 3 m, wood and plastic drums

2 × 2 × 2.5 m or coco lumber, with empty

200 l plastic drums

5 × 5 × 2 m or 3 × 3 × 3 m, galvanized iron,wood, bamboo, empty plastic drums,carboys, concrete weight

7 × 8 × 2 m

3 × 3 × 2 m, bamboo frame, polythene netand 200 l plastic drums

1 × 1 × 1 m (for juveniles), 2.5 × 2.5 × 4 m(grow-out)

Stocking density is 20–30 fish m measuring 9–10 cm, feedingwith commercial feeds; 7–8 or 12–14 months of culture;

production of 600–800 g per fish or 1.2–1.4 g per fishStocking density is 44 fish m−3of size 80–100 g; feeding withtrash fish at 3–5% of body weight twice daily; 6–7 months ofculture; production of 600 g per fish, 90% survival

Stocking density is 120 fish m−3of size 13–15 cm (grow-out),5–13 cm (transition), or 2–3 cm (nursery); feeding with drypellets and minced trash fish (grow-out) orChlorella,BrachionusandArtemia(nursery); FCR of 2.5–2.8:1 for drypellets and 6.3:1 for trash fish; culture period of 1 month(nursery), 3 months (transition) or 8 months (grow-out);

production of 500–800 g per fishStocking density is 10–100 m−3of size 7.5–10 cm; feeding withartificial feeds and live or frozen trash fish and crustaceans,feeds given at 10% body weight during the first 2 months, 5%

thereafter until harvest; 8 months culture period; production of

580 g per fish, 80% survivalStocking density is 12–100 m−3of size 12 cm or 20 g; feedsgiven at 10% of body weight on the first 2 months, then at 5%

on the third month; 10–18 months culture period; production of700–900 g per fish

Stocking density is 90 fish m−3of size 12 cm or 20 g; feedingwith chopped carangids (Seloroidesspp.), feed given twicedaily to satiation; 10 months culture period; production of 890 gper fish, 83% survival

Stocking density is 6 fish m−3of size 30 g or 100 fish m−3of size

10 cm or 20 g; feeding with trash fish once or twice a day; 9–10months culture period; production of 500–960 g per fish, 95%

Thailand (Tookwinas,1990a)

Thailand (Chaitanawisutiand Piyatiratitivorakul,1994b)

Thailand (Doi andSinghagraiwan, 1993)

Continued

5 × 5 × 3 m, wood and plastic drums

Square, circle cages of size 4 × 4 × 3 m,

4 × 4 × 4 m, 5 × 5 × 5 m, 7 × 7 × 7 m or

20 × 20 × 5 m, cages may be synthetic,nylon-coated wire or bamboo with styrofoam

as buoySquare, circle net enclosures made ofbamboo, wood, 50 mm steel pipes; also bigopen sea cages of sizes 1600–2400 m2with1–6 cm mesh nets

Square broodstock floating netcages

5 × 5 × 5 m

1 × 1 × 1.5 m cages housed in 6 × 6 mfloating raft

Bamboo cages 3 × 4 × 0.5 m

2000 × 5000 m3pens made of casuarinapoles and bamboo and with monofilamentnylon fabric (30 cm mesh)

1.5 × 2 × 1 m cage made of bamboo andwood

Stocking density is 44 fish m−3of size 80–100 g; feeding withtrash fish at 3–5% of body weight once or twice daily; 6–7months of culture; production of 600 g per fish

Stocking density is 100 fish m−3(1-year-old fish); feeding withtrash fish (anchovy and sardines) and moist pellets; 1–7 yearsculture period; production of 800 g to 1.4 kg per fish

Stocking density is 115–340 fish m−3of size 200–500 g or 5 fish

m−3for size 1 kg; feeding with trash fish (anchovy, sardines,sand lance) and moist pellets; feed given 1–4× daily at 1–3% ofbody weight or at 4–8% of body weight for fish less than 100 g;

FCR of about 5–9:1; 1–2 years culture period; production of2.5–6 kg per fish

Stocking density is 25 fish of size 0.89 g per cage; feeding withmoist pellets once every 2 days at 3% of body weight; 20months culture period or until fish reach maturity and spawning(about 3.7 kg size)

Stocking density is 15 fish of size 48–68 g per cage; feedingwith formulated diet, given 2× daily to satiation; 100 days cultureperiod; production of 119 g per fish, 100% survival

Stocking density is 1 kg m−3(8–10 fish per kg); no feeding; 6months of culture in sewage canal; production of 800 g per fishStocking density is 4–5 million fish ha−1(3-day-old

hatchery-reared); feeding with a mixture of groundnut, oil cakeand rice bran; with periodic dressing of organic (manure) andinorganic fertilizers; 3–4 months of culture

Stocking density is 15 fish m−3of size 14 g or 9 cm; feeding withyam and formulated diet, 3× daily at 5% of body weight;

18 weeks of culture; production of 180 g fish, 99% survival

Indonesia (Taconet al.,1990)

Indonesia (Costa-Pierceand Effendi, 1988)India (Basavaraja, 1994)

Malaysia (Anget al.,1988)

FCR, food conversion ratio

Table 1.3. Continued

have a rigid wooden or metal framework

surrounded by a catwalk to facilitate

operation and maintenance The net bag is

supported by a buoyant collar or a frame,

and can be designed in various shapes and

sizes.

Floats Common flotation materials

in-clude metal, plastic drums, PVC pipes,

Sty-rofoam, cement blocks, rubber tyres with

polystyrene, bamboo and logs Metal drums

coated with tar or fibreglass are popular

because they are cheap, but they corrode

easily in seawater and have a life span

ranging from 0.5 to 3 years (IDRC, 1979).

Fibreglass drums or buoys are preferred by

commercial fish farmers as they can last for

many years in seawater although the initial

cost is comparatively higher Styrofoam

blocks, covered with polythene sheets

provide good buoyancy and may last for as

long as 5 years under tropical conditions.

Cement floats, though promising, require

skill in construction and are presently not

widely used Bamboo and logs widely

used in freshwater cages are also used in

constructing brackish and marine cages, but

they are easily attacked by fouling and

boring organisms Their life span in seawater

is relatively short (1–2 years).

Catwalk For cages designed with a

cat-walk, the framework from which a single

net or a battery of nets is suspended is

usually large to provide a stable and rigid

platform for workers Some marine cages

do not have catwalks and the surface unit consists of floats from which each cage is suspended.

Netcage proper The netcage (Fig 1.1) is

normally flexible, and made up of synthetic netting of nylon or polythene fibres reinforced at the corners with polythene ropes The nets are kept stretched vertically with weights at the bottom of the cage or fastened by rope to the framework (Kennedy, 1975) The net can also be stretched with rectangular, round or square steel or PVC pipes depending on the shape of the cage Rigid cages, made of metal netting (galvanized mesh, copper–nickel mesh or vinyl-coated mesh) mounted on rigid metal

or wooden frameworks, are also commonly used in sea farming (Swingle, 1971; Powell, 1976; Milne, 1979) The relative merits of flexible and rigid cages are discussed by Hugenin and Ansuini (1978) The choice

of flexible or rigid types is dependent on economics Flexible cages are more widely used in developing countries because of lower cost.

Mesh size This is determined by the size of

the fish to be stocked Small mesh size nets become clogged, especially in tropical areas, and easily damaged by floating objects and increased drag force and hence affect the morning load of the cages As the fish grow,

a larger mesh size should be used (Chua, 1979).

Fig 1.1 Set net showing typical netcage structure (King Chou Fish Net Manufacturing Co., Ltd).

Rotating and non-rotating floating cages

Rotating cages have been designed

primarily to reduce the impact of fouling

organisms and insects The cage rotates

from a central axis attached to a solid

floating framework (Christensen, 1995).

Non-rotating types are widely used and may

be designed with narrow or wide collars.

Rigid narrow collars made of non-wooden

materials (glass fibre and steel) and buoys

have been used in Western Europe.

Submersible cages

Submersible cages (Figs 1.2–1.4) have also

been developed This type of cage design

has no collar, and the bag rests on a frame

to maintain its shape The position of

submersible cages (with reference to the

water column) can be adjusted by means

of buoys The cages are designed for deep

waters, to overcome strong waves, and

strong and rough seas The disadvantage of

submersible cages is that it is difficult to

maintain the bag shape under water and

not many species adapt to this condition

(Beveridge, 1987) Submerged cages are also used in shallow water in Indonesia and Russia (Vass and Sachlan, 1957; Martyshev, 1983; Beveridge, 1987).

Shape and size of cages

In general, square or rectangular cages are preferred because they are easy to construct and maintain They have been widely used for the culture of yellowtail (Harada, 1970; Fujiya, 1979), salmonids (Kennedy, 1975; Møller, 1979) and groupers (Chua, 1979) Cylindrical cages are also used for marine

or brackish water species such as milkfish

(Yu et al., 1979) and rainbow trout (Tatum,

1973) Cylindrical cages are designed to rotate so as to delay biofouling (Caillouet, 1972) Other forms of cages such as orthogo- nal (Anon., 1976; Milne, 1979) and octagonal (Møller, 1979) have been used for salmonid culture in Scotland, Norway and France The size of cages ranges from less than

1 m3 to 50,000 m3 Freshwater cages for tilapia in the Philippines and Indonesia are

Fig 1.2 Submersible cage for yellowtail (from Fujiya, 1979).

usually very large (exceeding 100 m3) and

are installed in calm shallow lakes (Chua,

1982) Currently, dimensions for marine

cages are usually smaller, even in relatively

calm waters, because large nets are difficult

to maintain due to biofouling problems in

the marine environment Although large

size cages reduce construction costs, the

optimum size must be within the physical

capacity of the fish farmer(s) to manage and maintain For tropical conditions where biofouling can be rapid and heavy, net cage sizes are between 20 and 50 m3 Various shapes and sizes of traditional cage struc- tures are shown in Figs 1.5 and 1.6 Figures 1.7–1.14 show other modifications in cage structures and set-ups that have been devel- oped through the years.

Fig 1.3 Submerged trout cage, Russia (Martyshev, 1983).

Fig 1.4 Submerged cage (King Chou Fish Net Manufacturing Co., Ltd).

Cage Culture Operations

Stocking

The stocking density depends on the carrying capacity of the cages and the feed- ing habits of the cultured species For fish

such as bighead (Aristichthys mobilis) and silver carp (Hypophthalmicthys molitrix),

which are low in the food chain, stocking will also depend on the primary and secondary productivity of the sites When feeding is required, the rate of water exchange is an important consideration Studies have shown that optimal stocking density varies with species and size of fish (Brown, 1946; Chua and Teng, 1979) As stocking density affects the growth rate of

fish (Stickney et al., 1972; Allen, 1974; Kilambi et al., 1977), determination of the

optimal stocking density is important in

Fig 1.5 Square cage (Fong Yu).

Fig 1.6 Square cage (Water Diamond Equipment Co., Ltd).

Fig 1.7 Cage structures by EKSPORTFINANS

ASA

cage culture High stocking density may

create group effects resulting in high

mor-tality, as in estuary grouper (Epinephelus

salmoides) (Chua and Teng, 1978) Optimal

stocking density ensures optimum yield for food conversion, and low disease prevalence with good survival rate.

Feeding

Feeding is a vital operational function and is affected by the interplay of many biological, climatic, environmental (water quality) and economic factors Growth rate

is affected by feeding intensity and feeding time (Chua, 1982) Each fish species varies in maximum food intake, feeding frequency, digestibility and conversion efficiency These in turn affect the net yield, survival rates, size of fish and overall production of the cage Trash fish is the main feed for yellowtail, grouper, bream, snapper and other carnivorous species cultured in marine cages (Anon., 1986; Quinitio and Toledo, 1991; Doi and Singhagraiwan, 1993; Leong, 1998) The shortage of trash fish as feed is a serious problem in Thailand, where the large-scale development of catfish farming has resulted

in increased demand for trash fish (Chua,

Fig 1.8 Prototype of modular steel cage: 8 × 8 m module can be divided into four 4 × 4 m cages (Cruz,

1998)

Fig 1.9 Main cage structure with security chain.

1982; Shepherd and Bromage, 1988;

Fukumoto, 1989) The shortage of trash fish

and fishmeal is recognized as an increasing

problem in aquaculture (Chua, 1982) This

concern has been addressed by research

institutions and the private sector, bringing

forth developments and innovations in

formulated diet research.

Farm management

Farm management must optimize

produc-tion at minimum cost Efficient

manage-ment depends heavily on the competence

and experience of the farm operator The

operator has to ensure that the cultured fish grow at the expected rate with respect to feeding rate and stocking density, minimize losses due to disease and predators, monitor environmental parameters and maintain efficiency of the technical facilities (Chua, 1982).

Maintenance work is also of vital tance The entire structure (raft and netcages) must be routinely inspected Necessary repairs and adjustments to anchor ropes and netcages should be carried out immediately Plastic drum floats have to be regularly painted with non-toxic antifouling paints Scraping accumulated fouling organisms may be carried out by rotating the drums regularly Monthly replacement of net

Fig 1.10 Ocean catamaran fish farm.

Fig 1.11 Aqualine prefabricated mooring system.