Capture Based Aquaculture (CBA)
BIO 208 - 2016 9.0 Capture Based Aquaculture What happens in a hatchery? Life Cycle Closure
BIO 208 - 2016 9.0 Capture Based Aquaculture Capture -based aquaculture - many socio-economic benefits to local communities
Catfish, West Africa
Groupers, S.E. Asia Environmental Issues: A. Direct effects - Resource removal - overfishing - bycatch and discards - direct physical disturbance and habitat destruction B. Indirect effects - use of raw fish as feed ( ¨trash fish ¨) - organic pollution - disease BIO 208 - 2016 9.0 Capture Based Aquaculture Capture-based aquaculture - main species
BIO 208 - 2016 9.0 Capture Based Aquaculture BIO 208 - 2016 9.0 Capture Based Aquaculture BIO 208 - 2016 9.0 Capture Based Aquaculture Estimates for capture -based aquaculture production of eels, groupers, and tunas in 2009 (FAO)
Species group Estimated production (thousand tonnes) Eels 275
Groupers 75
Tunas 9
Value (FAO data) US$1.7 billion
BIO 208 - 2016 9.0 Capture Based Aquaculture CAPTURE -BASED AQUACULTURE
A. Direct effects - Resource removal 1. Use of wild seed
∑ By definition, CBA relies on the use of wild-caught ¨seed ¨(a term that covers fry, juveniles, and in some cases larger fish) for stocking on-growing facilities.
∑ Many of the species targeted are already threatened.
∑ There is particular concern over the targeted high value species (grouper, tuna, spiny lobster), especially those which have a low reproductive capacity (mature at a large size) such as tuna and groupers.
∑ The source of seed will be unsustainable in the long term as the catch per unit effort of seed declines with increased exploitation.
∑ The transfer of seed to CBA farms is often characterized by high mortality rates.
BIO 208 - 2016 9.0 Capture Based Aquaculture CAPTURE -BASED AQUACULTURE
A. Direct effects - Resource removal 2. Bycatch and discards
ß The collection of seed for CBA can lead to high mortality of non-target species. ß Milkfish fry constitute 15% of total finfish fry collected by inshore netting - remaining 85% are discarded and left to die.
- thus the 1.7 billion wild fry stocked annually in the Phillipines results in the loss of about 10 billion fry of other non target finfish species. ß In India and Bangladesh, ca. 160 fish and shrimp fry are discarded for every fry of the giant tiger shrimp, Penaeus monodon collected.
3. Direct physical disturbance and habitat destruction ß Dredging for seed mussels.
BIO 208 - 2016 9.0 Capture Based Aquaculture CAPTURE -BASED AQUACULTURE
B. Indirect effects 1. The use of raw fish as feed ( ¨trash fish ¨)
ß Many forms of capture-based aquaculture still use raw fish as the main form of feed (generally referred to as ¨trash fish ¨).
ß This raises a number of environmental issues, including:
- depletion of stocks
- poor quality of feed - potential transfer of disease vectors to farmed fish, and indeed wild fish
- the transfer of human pathogens is also possible.
- very high feed conversion rations and high waste levels - leads to enhanced organic pollution.
BIO 208 - 2016 9.0 Capture Based Aquaculture CAPTURE -BASED AQUACULTURE
B. Indirect effects 1. Organic pollution
ß Can be high levels of localized organic pollution, especially when the CBA farm is using trash fish as the main source of feed (groupers, spiny lobster). ß Can lead to algal blooms
2. Disease
ß Intensive cultivation in cages can increase the risk of transfer of diseases and parasites.
ß This risk is increased with the use of trash fish (often of poor quality)
BIO 208 - 2016 9.0 Capture Based Aquaculture Capture -based Aquaculture Two internationally important species.
Bluefin tuna, Thunnus thynnus
European eel Anguilla anguilla
BIO 208 - 2016 9.0 Capture Based Aquaculture Bluefin tuna:life, fisheries and aquaculture implications
Beatriz Morales-Nin IMEDEA, Esporles, Spain
BIO 208 - 2016 9.0 Capture Based Aquaculture The most valuable fish in the world!
January 2013: A single 220 kg fish sells in Tsu Kiji’s market for € 1 350 000 !!!!!!!!!!! 6 000 €/kg first sale price 1 fish= 10 million NOK, 1 kg=45000 NOK
BIO 208 - 2016 9.0 Capture Based Aquaculture Bluefin tuna Thunnus thynnus
• Family Scombridae • Very evolved species • Adaptations in the circulatory system to recover heath generated by muscles • Body temperature control up to 21º C over water temperature • High metabolism • High swimming speed (up to 30 km/h) • Aceleration 70-100 km in 2 seconds • Fast growth • Maximum size 6 m and 700 kg • Life span up to 30 yr • Maturity 5-8 yr(16-25 kg) • 45.000.000 eggs/spawning • Top predator
BIO 208 - 2016 9.0 Capture Based Aquaculture Thunnus thynnus
• Very mobile fish • Wide habitat range • Spawning and foraging seasonal migrations • Aristotle (4th cent) & Plinio (1st cent) first descriptions in the Mediterranean • 17th cent. the connectivity between Med& Atlantic postulated and accepted in 1960 • Spawning site fidelity in Mediterranean and Gulf of Mexico
BIO 208 - 2016 9.0 Capture Based Aquaculture Vertical migrations
• Top predators with opportunistic diet • Exploiting the water column fishing down to 800-1.000 m • Exploiting deep scattering layer
BIO 208 - 2016 9.0 Capture Based Aquaculture Stock structure
• Two main stocks • 50% tuna fished in North America of Mediterranean origin • Probably intermixing albeit 90% fish returning to their natal origin for spawning • 30% population doing cross Atlantic migrations (60 days)
BIO 208 - 2016 9.0 Capture Based Aquaculture Spawning areas related to oceanographic conditions
F.Alemany, IEO-COB
BIO 208 - 2016 9.0 Capture Based Aquaculture Explotation
‹Almost 4000yrs of exploitation!
‹Commercial fishery from boat ‹Purse seine nets ‹Surface long liners ‹Hand lines
‹Commercial fishery from land ‹Almadrabas
‹Recreational angling
2800 BC – 470 AD Phoenicians and Romans had factories in Spain for dry & salt tuna and
BIO 208 - 2016 9.0 Capture Based Aquaculture garum Almadrabas
• Fix traps used since ancient times first in the Gibraltar Strait and after in all Mediterranean • In Spain records from the 12th cent. • Azahara de los atunes: • 1558 catch: 140.152 bluefins • 1949 catch: 43.500 bluefins • 2006 catch: 1.600 bluefins • Mean catch in Italy and Spain 15000 tonne/yr from 16th – 20th century
BIO 208 - 2016 9.0 Capture Based Aquaculture BIO 208 - 2016 9.0 Capture Based Aquaculture • Interannual fluctuations related to oceanographic Tuna catches conditions and variations in fishing effort
ICCAT
In 50 yr 90% reduction landings, ex. Almadrabas: ‹1980 60 tm/week, mean weight 65 kg/atún ‹2000 5 tm/week, mean weight 22 kg/atún ‹catches are over 2.5 x the sustainable level
BIO 208 - 2016 9.0 Capture Based Aquaculture Overexploitation •Expansion of the fleet capacity •Technological improvement •Expansion ofthe fishing areas In 50 yr 90% reduction landings: ‹1980 60 tm/week, mean weight 65 kg ‹2000 5 tm/week, mean weight 22 kg ‹catches are over 2.5 x the sustainable level
ICCAT/ICES
19th cent hand-line fisheries G.Vizcaya, live bait 1930 N Atlantic purse seiners 1960 W Atlantic hand line for juveniles and 1970 for reproducing adults 1980 Central and E Mediterranean BIO 208 - 2016 9.0 Capture Based Aquaculture Management
• Trans frontier migratory species: resources shared by several countries • Fished by diferent gears and fleets • Managed by International Comision Conservation Tunas (http://www.iccat.int/en/) • Regulations based on quotas by countries, minimum lengths, gear restrictions, closed seasons
BIO 208 - 2016 9.0 Capture Based Aquaculture Management
Compliance: systematic failure and cheating •Changes of ship flags •Use of forbidden gears and methods •Catches of fish under legal size (30 kg) •Cheating minimum size because of “traditional activity” •Declaring farms produce as aquiculture (without quota) •Unreporting catches………… •2005 ICCAT set quota at 32 000 tn •2005 WWF/Adena estimated catches at 45 000 tn •2005 France+Libya quota 7 500 tn, captured 12 800! •Estimated catches 4 times over the reccomended by ICCAT
BIO 208 - 2016 9.0 Capture Based Aquaculture Tuna farming –problems , not solutions . Why ?
• Domestication not yet completed • Spawning in captivity • Not closed cycle • Main problem survival larvae- juvenile • Wild fish fattening 90’s • Mediterranean tuna captured by purse-seine transferred to floating cages • Captivity from 6-7 month up to 2 yr • Market reasons: • Fat fish better prize in Japan • Available supply all year
BIO 208 - 2016 9.0 Capture Based Aquaculture Tuna farming expansion
• 60’s Canada first farm • 1979 Ceuta (Spain) fattening of spent adults (>150 kg) from the traps for 5 months (200 t) • Australia farms introduce change to middle-small fish • 1996 expansion to the Med farming 20-80 kg immature fish up to 2 years • Inclusion of very small fish down to 10 kg
BIO 208 - 2016 9.0 Capture Based Aquaculture Rapid expansion
BIO 208 - 2016 9.0 Capture Based Aquaculture Where else are tuna being farmed?
∑Mediterranean (Spain, Croatia, Malta) - Thunnus thynnus ∑Japan - Thunnus thynnus ∑Canada - Thunnus thynnus ∑South Australia - Thunnus maccoyii ∑Mexcio - Thunnus thynnus, bigeye, Thunnus obesus, yellowfin, Thunnus albacares
BIO 208 - 2016 9.0 Capture Based Aquaculture Capture of live tuna
1. Purse seine ß1-2 km in length. Pulled in until c.100 m in diameter. ßPurse seining accounts for 60-80% tuna catch.
2. Hook and line ßUses barbless hooks, baited with live fish.
Mediterranean 2003 21,000 tonnes of wild-caught tuna were introduced to pens (compared to a total quota for the Mediterranean and eastern Atlantic of 32,000 tonnes).
BIO 208 - 2016 9.0 Capture Based Aquaculture Tuna aquaculture: the farming process
1. Capture of live tuna - purse seine 2. Tuna transferred to cages to be towed away
3. Transfer to growout cages. 4. Harvest of tuna Tuna fed a diet of fish, squid or pellets . BIO 208 - 2016 9.0 Capture Based 4.Aquaculture Harvest Construction and assembly of tuna pens
BIO 208 - 2016 9.0 Capture Based Aquaculture BIO 208 - 2016 9.0 Capture Based Aquaculture Tuna
BIO 208 - 2016 9.0 Capture Based Aquaculture Farming implications – Consequences of CBA
overfishing Farms
•Tuna •Environmental populations impacts •Small-pelagics •Social for feeder implications
BIO 208 - 2016 9.0 Capture Based Aquaculture Tuna farming • Depleting overexploited Tuna stocks • Declared as aquaculture production but only 10- 15% weigh gain in captivity • Bad conversion rate 25kg •2005 a total of 28450 tn were food to 1 kg tuna (over fished for fattening in the Med •90% total quota for the W exploitation small pelagic Atlantic+Mediterranean fish) •Profit : Japan imports 1.490.000.000 $ on 9 months in 2005! •Now 64 farms in the Med
BIO 208 - 2016 9.0 Capture Based Aquaculture Farming implications – Consequences of CBA POLLUTION • Generation of a wide • Benthic impact range of dissolved and • Accumulation of C, changes in P load particulate matter from • Reduction of Redox the fish and food left potential overs • Increase bacterial load • Processing of the fish • Changes in nematodes • Increase in pathogen indigenous bacteria • Increase in pelagic productivity eutrophication
BIO 208 - 2016 9.0 Capture Based Aquaculture Farming implications – Consequences of CBA FISHERIES •Changes in the purse-seine fleet • Socio-economic changes activity in the fisheries and •Up to 50% captures purse seines fishing communnity for farming • Changes in Japanese •Uncertainity of the catches markets volume, area and time of capture •Changes in the demand of bait fish (pelagics and cephalopods) •Changes in the sashimi market prices and demands
BIO 208 - 2016 9.0 Capture Based Aquaculture Farming implications – Consequences of CBA • Fabulous profit resulted in rapid tuna farming increase • It is not aquaculture, only fattening wild fish • Activity started with already overexploited stocks • EU subsidies to Mediterranean farms up to 20 million € • Purse seine fleet working for the farms modernized and creating fleet overcapacity with 35 million € subsidies
BIO 208 - 2016 9.0 Capture Based Aquaculture Impact of Tuna farming in the Mediterranean
• Overexploitation of small pelagics for feeding the tuna • Contamination of coastal areas • Decrease in top predators and alterations of the food- web • Bluefin tuna listed in the IUNC’s red list • Listed as species of concern by NOAA
BIO 208 - 2016 9.0 Capture Based Aquaculture CBA Remember this poster? Tuna
BIO 208 - 2016 9.0 Capture Based Aquaculture How Tuna Farming SHOULD Work
Tuna Kinki University, Osaka Japan
32 Years of
Research! Adults mature at 5 yr Eggs hatch at 48 hr – larvae 3mm 1970 - 2002 200kg Fed on plankton
3 years – 30 kg 20 days – moved to 3 months – 300g Market size cages
BIO 208 - 2016 9.0 Capture Based Aquaculture Capture Based Aquaculture of Eel , Anguilla sp.
The genus Anguilla consists of 18 species. 4 species are farmed successfully:
Anguilla anguilla, European eel A. japonica, Japanese eel A. rostrata , American eel A. australis , shortfin eel
Eel culture research in Denmark
BIO 208 - 2016 9.0 Capture Based Aquaculture Eel culture
BIO 208 - 2016 9.0 Capture Based Aquaculture Life -cycle of the European eel
Adult silver eel
Glass eels
leptocephalus
BIO 208 - 2016 9.0 Capture Based Aquaculture Collection and transportation of glass eels
Tank truck transport within Europe. Up to 2,000 kg of glass eels in a single truck, running on pure oxygen, for 36 hours transportation. 12 tanks each holding 2,400 litres of water. Air freight - several types of polystyrene boxes, often chilled used.
BIO 208 - 2016 9.0 Capture Based Aquaculture Intensive cultivation of eels
BIO 208 - 2016 9.0 Capture Based Aquaculture Reduction in catches of glass eels across Europe
BIO 208 - 2016 9.0 Capture Based Aquaculture Eel cultivation - facts
• Annual production of eel (all species) is about 250,000 tonnes, of which 95 % comes from aquaculture. • Nearly 90% of world production of farmed eels comes from Asia. • Huge demand for glass eels. • Originally, Chinese eel production used mainly Japanese glass eels. Japanese glass eel catches fell from 140 tonnes in 1965 to less than 40 tonnes in 2000. • Up until the late 1980s, only 3% of Asian eel production came from European glass eels. By the end of the 1990s this figure had risen to 80%. • Annual European glass eel catch in the late 1990s was 130-150 tonnes, with Asian traders buying up to 75%. China buys 80-100 tonnes of European glass eels. • European glass eels cost US$ 300/kilo, while Japanese glass eels can cost up to US$ 10,000/kilo.
BIO 208 - 2016 9.0 Capture Based Aquaculture BIO 208 - 2016 9.0 Capture Based Aquaculture Capture Based 4000 t in 2014 Aquaculture of Cod in Norway
Nofima ’s «Fish Hotels» take in Live Capture cod for fattening and to spread the sales over time
BIO 208 - 2016 9.0 Capture Based Aquaculture Capture -based aquaculture – future prospects
1. Supply of Hatchery-reared seed to reduce impact on wild populations
ß Major advances have been made towards the hatchery production of several species currently reared through CBA.
ß In Japan, bluefin tuna broodstocks and closed-cycle breeding.
ß Natural spawning of wild-caught greater amberjacks and longfin or Almaco jack was achieved in Hawaii in 1999; since then, domesticated F1 and F2 stocks have been used as broodstock.
ß 15-30% of farmed groupers in Indonesia come from hatchery-reared seed.
Does not solve the «fattening» business
BIO 208 - 2016 9.0 Capture Based Aquaculture Capture -based aquaculture
Possible solutions 2. Feed developments - Increasing trend to replace the traditionally used raw fish diets (trash fish) with formulated diets.
ß Raw fish remains the most commonly used type of feed for groupers, despite decades of research aimed at producing pelleted substitutes. Commercial grouper feed available in the Philippines
ß Raw fish was traditionally used in the production of yellowtails in Japan. However, since the early 1990s the use of moist or semi-moist pellets has been increasing to replace raw fish
BIO 208 - 2016 9.0 Capture Based Aquaculture Capture Based Aquaculture
Case Studies Yellowtail/Amberjack Milkfish Grouper Spiny Rock Lobster
BIO 208 - 2016 9.0 Capture Based Aquaculture Capture-based aquaculture 2. Yellowtails
Yellowtails Genus Seriola (47 species)
Seriola quinqueradiata Yellowtail or Japanese amberjack S. dumerili Greater amberjack S. lalandi Yellowtail amberjack or Goldstriped amberjack
BIO 208 - 2016 9.0 Capture Based Aquaculture Yellowtail culture
History ßYellowtail culture dates back to 1927 in Japan. ßThe commercial culture of yellowtail expanded in the 1940s ßIn Japan, production peaked at 170,000 mt in 1995 ßAlthough yellowtail culture occurs throughout the Pacific and Mediterranean, it is especially important in Japan. ßIn 2003, Japanese yellowtail accounted for 57% of the total farmed marine fish production in Japan. ßEven though yellowtail has spawned in captivity, yellowtail culture still relies on the capture of wild ¨seed ¨. ßJapan catches over 40 million juvenile (10-50 gms) Japanese amber jack annually - called ¨mojako ¨
BIO 208 - 2016 9.0 Capture Based Aquaculture Yellowtail culture
∑Juveniles caught at sea in late spring ( ¨mojako ¨ 10 - 50 gms) ∑Initially grown in 2 x 2 x 2 m net cages until December, when the yellowtail have reached a size of 700 - 2000 gms. ∑Moved to larger net cages (10 x 10 x 10 m, but can be as large as 50 x 50 x 50 m). Generally 25,000 fish stocked per net cage. ∑Harvested following year when the fish have reached 2-5 kg, or left a further year until the fish have reached 7-8 kg.
BIO 208 - 2016 9.0 Capture Based Aquaculture Global production of Japanese amberjack
BIO 208 - 2016 9.0 Capture Based Aquaculture Japanese amberjack: production cycle
BIO 208 - 2016 9.0 Capture Based Aquaculture BIO 208 - 2016 9.0 Capture Based Aquaculture BIO 208 - 2016 9.0 Capture Based Aquaculture BIO 208 - 2016 9.0 Capture Based Aquaculture BIO 208 - 2016 9.0 Capture Based Aquaculture BIO 208 - 2016 9.0 Capture Based Aquaculture BIO 208 - 2016 9.0 Capture Based Aquaculture BIO 208 - 2016 9.0 Capture Based Aquaculture BIO 208 - 2016 9.0 Capture Based Aquaculture BIO 208 - 2016 9.0 Capture Based Aquaculture Japanese amberjack production
ß Although Japanese amberjack production is well established, future expansion is limited by the supply of juveniles.
ß Although juveniles are available from commercial hatcheries their quality is poor compared to wild-caught juveniles.
ß Still major problems with larval rearing - often very high mortalities.
ß Major environmental issues: ° depletion of wild stocks (need to improve hatchery production of juveniles) ° developmental of successful feeds ° extruded feeds account for about 40% feed used ° remaining 60% is moist pellets and raw fish ° better management practices to limit losses from toxic algal blooms, especially ¨red tide ¨ blooms - probably due to poor feed regimes.
BIO 208 - 2016 9.0 Capture Based Aquaculture 3. The milkfish, Chanos chanos
Biology ßThe milkfish occurs throughout the Indo-Pacific region. ßThe adults are pelagic, schooling and migratory. ßAdults are large (1.5 m and 20 kg), live to 15 years and mature at 5 years. ßMilkfish are euryhaline and plankivorous ßSpawning occurs near coral reefs during March-May. The pelagic eggs and larvae remain in the plankton for 2 weeks then migrate into shallow coastal waters, especially coastal lagoons and mangrove areas. ßEarly fry are 10-17 mm in length. ßJuveniles remain in these coastal habitats until maturation, when they migrate back out to sea.
BIO 208 - 2016 9.0 Capture Based Aquaculture Milkfish - culture systems and practices
ßMilkfish farming is a centuries-old industry in Indonesia, the Philippines and Taiwan.
ßIn these three countries, 365,000 ha of brackish-water ponds and 7,000 ha of fishpens produce 230,000 tonnes of milkfish annually.
ßMilkfish cultivation is best suited to brackish-water.
ßThe milkfish is relatively disease resistant, feeds near the bottom of the food chain and has a rapid growth rate.
ßHowever, the milkfish will not reproduce naturally in brackish-water.
ßMost milkfish production still relies on wild-caught fry (seed fish).
BIO 208 - 2016 9.0 Capture Based Aquaculture Milkfish culture
BIO 208 - 2016 9.0 Capture Based Aquaculture There are three forms of milkfish cultivation: extensive semi-intensive intensive
Stocking density Culture period Harvest size Production (fish /m 3) (days) kg/ha/year
Extensive 0.2-6.0 30-75 200-400 700-1000
Semi-intensive 0.8-1.2 60-135 300-500 2000-4000
Intensive > 2.0 120-150 300-500 4000-12000
ß Fry (12-16 mm) caught by beach seining in April-July and transferred to nursery ponds (75-100/m 3). 4 weeks ß Fingerlings (5-10 cm) transferred to either brackish water ponds (extensive and semi- intensive cultivation) or to freshwater pens (intensive cultivation). ß Large numbers are harvested at 75 gms to be used as live bait for the tuna industry ß 3-8 harvests/year
BIO 208 - 2016 9.0 Capture Based Aquaculture Milkfish farming
1. Extensive milkfish culture uses large (5-10 ha), shallow (30-50 cm) brackish water ponds. Production relies on natural food, which is enhanced by occasional fertilization. Stocks are moved on to new ponds when natural food becomes limiting. 2. In semi-intensive culture , yield increases 200-400% by employing supplemental feeding, deeper water and more frequent water changes. 3. Intensive culture uses smaller pens or cages (2-5m deep), usually in freshwater. Supplement feed is given, and the pens are supported by pumping and aeration facilities , allowing yields in excess of ten fold greater than extensive culture.
ß NB. Very good feed conversion ratios are obtained in all forms of milkfish culture, generally around 1.4 for semi-intensive and intensive culture, and even < 1 for extensive culture.
BIO 208 - 2016 9.0 Capture Based Aquaculture Milkfish production
Milkfish pen in estuary Brackish-water growout
Broodstock tank Floating net cages BIO 208 - 2016 9.0 Capture Based Aquaculture Milkfish production cycles
BIO 208 - 2016 9.0 Capture Based Aquaculture 5. Groupers Major grouper species used in aquaculture
Epinephelus coioides ßWidely distributed species throughout the Indo-Pacific. ßOne of the major grouper species cultured for the live reef fish trade. ßWidely cultured throughout southeast Asia.
Cromileptes altivelis ßWidely distributed throughout the Western Pacific. ßA high-value species in the live reef fish trade, fetching up to US$70 per kg.
Epinephelus fuscoguttatus ßWidely distributed throughout the Indo-Pacific region. ßMedium-priced species ßJuveniles in great demand as this grouper survives well, and grows rapidly under culture conditions.
BIO 208 - 2016 9.0 Capture Based Aquaculture Aquaculture of grouper in SE Asia - current status
ßMarine cage cultivation of grouper is expanding throughout Southeast Asia.
ßMany groupers (Family Serranidae , Subfamily Epinephelinae ) fetch very high prices (up to US$70/kg) on the international market, and the future export potential is considered to be very high .
ßWorldwide, most grouper aquaculture production is in Southeast Asia, with Taiwan, Indonesia, Thailand and Malyasia being the main producers (see following table).
ßBesides official figures, unofficial reports indicate that China produced 8256 mt of grouper in 1997, while in 2001 Vietnam produced 2600 mt of marine fish, of which a high proportion was grouper.
ßTogether, this suggests that the regional total aquaculture production of groupers in 2001 was more than 23,000 mt, valued at US$160 million.
BIO 208 - 2016 9.0 Capture Based Aquaculture Global production (metric tonnes) and total value of grouper aquaculture, 1990 - 2001 (FAO).
BIO 208 - 2016 9.0 Capture Based Aquaculture Development of methodologies to improve marine fish aquaculture in SE Asia.
ßDespite the continuing expansion of grouper aquaculture throughout Southeast Asia, there remain a number of major constraints to the sustainable development of this form of marine aquaculture .
ßThese constrains, which often apply to other important marine species, include:
1) The full control over the life-cycle production of grouper is still lacking , and as a result grouper aquaculture remains heavily dependent on the capture of wild juveniles (fingerlings). The availability of juveniles is presently one of the major constraints restricting the increase in grouper aquaculture.
2) During the grow-out phase, grouper are still primarily fed ‘ trash fish ’ as apposed to compound pelleted feeds. In view of the environmental impact of using trash fish, the development of appropriate formulated pelleted feed is urgently needed.
BIO 208 - 2016 9.0 Capture Based Aquaculture Grouper aquaculture
Grow-out phase ß The grow-out phase in grouper aquaculture involves transferring juveniles to marine cages.
ß The major limitation to this stage of grouper cultivation is the availability of a suitable compound pellet feed.
ß To date, the marine cage culture of grouper throughout Southeast Asia primarily relies on feeding with ‘ trash fish’ . A number a major problems are associated with the practice of feeding trash fish, including:
- trash fish could be used for human consumption. - low efficiency of utilisation of trash fish (dry matter FCRs range between 5:1 and 10:1, compared to 1:1 and 2:1 for pellet feeds).
- localised organic pollution due to high levels of uneaten feed and faeces.
- inconsistent supply (supply of trash fish often seasonal).
- poor quality (increased likelihood of transfer of diseases).
BIO 208 - 2016 9.0 Capture Based Aquaculture BIO 208 - 2016 9.0 Capture Based Aquaculture 6. Spiny rock lobster
ßSpiny rock lobster ( Panuliris spp .)
ßThe most common and widespread species in the Pacific is the golden rock lobster P. penicillatus.
ßOther important species include: painted lobster , P. Versicolor striped leg lobster , P. Longipes femoristriga ornate lobster , P. Ornatus
ßAll are large species (adults > 25 cm in total length).
BIO 208 - 2016 9.0 Capture Based Aquaculture Spiny rock lobster - attributes for aquaculture
ßVery high value species, with excellent export potential.
ßLive lobsters exported from Vietnam to Hong Kong and Japan markets where they can fetch up to US$28 per kg.
ßEven though seed prices are high (US$5-10) lobster culture is very profitable, with operating profit in the order of 100%.
ßJuveniles easily captured.
ßLobsters are robust and easily cultured from juveniles to adults (800 gm or more) within 18 months.
ßCapital investment for on-growing of the lobsters is relatively low - suitable for subsistence farming.
BIO 208 - 2016 9.0 Capture Based Aquaculture Spiny rock lobster - culture methods
ßSuccessful hatchery production of spiny lobster is not yet developed.
ßSeed lobsters recruiting into shallow coastal reefs are easily caught.
ßCaptured lobster seed of > 25mm total length is easily on-grown. However, poor handling or overcrowding of the newly caught seed can result in high mortality (>30%).
ßSeed lobsters first grown in small floating net cages (100-200 seed/cage) until they attain a size of c. 50 g.
ßJuveniles transferred to larger grow-out cages (4x4x5 m) and grown to harvest size (around 1 kg within 18 months).
ßSurvival of lobsters from stocking into grow-out cages is high, typically 90%
BIO 208 - 2016 9.0 Capture Based Aquaculture Spiny rock lobster - environmental concerns
1) Most wild lobster fisheries are over exploited . The capture of large quantities of seed lobster adds to this pressure. However the following two points need to be mentioned:
∑ More research is needed to determine more fully the stock structures of spiny lobsters in the Pacific region, and to estimate recruitment patterns and survival rates.
∑ Compared to lobster aquaculture where survival from seed to adult is high (90%), recruitment of wild seed to the adult fishery is low (estimated at < 5%). Therefore capture of a modest proportion of the wild seed would benefit local aquaculture without significant detriment to the sustainability of the wild fishery in the Pacific region.
∑ That is, harvesting 0.5 million seed out of a total recruitment of 10 million seed annually would create an aquaculture industry of 300 tonnes/year.
BIO 208 - 2016 9.0 Capture Based Aquaculture Spiny rock lobster - environmental concerns
2. Localised pollution - the concentration of on-growing cages can be high. Organic pollution caused by excessive amounts of trash fish used as feed.
∑ A number of disease outbreaks have been reported in lobster aquaculture, and this has usually been attributed to pollution and poor water quality.
∑ For example, a bacterial disease affected caged lobsters in Vietnam in 2001 with losses as high as 20-30% of the cage in one week.
BIO 208 - 2016 9.0 Capture Based Aquaculture