Southeast Asian Fisheries Development Center Aquaculture Department
SEAFDEC/AQD Institutional Repository http://repository.seafdec.org.ph
Journals/Magazines Aqua Farm News
1994
Offshore fish farming
Aquaculture Department, Southeast Asian Fisheries Development Center
Southeast Asian Fisheries Development Center, Aquaculture Department (1994). Offshore fish farming. Aqua Farm News, 12(1), 16-17.
http://hdl.handle.net/10862/2501
Downloaded from http://repository.seafdec.org.ph, SEAFDEC/AQD's Institutional Repository
TECHNOLOGIES FOR FARMING THE SEA
Offshore fish farming
M arine fis h fa rm in g in pens and cages is new, a n d co n c e n tra te s m ainly on intensive p ro d u c tio n o f h ig h-value fish. S pecies grow n in o ffsh o re fa rm s include ye llow tail and red sea bream in Japan, sea b a ss and sea bream in the M e d iterranea n, and A tla n tic salm on in w estern E urope. T he salm on industry p rovides the most d ra m a tic illustration of te ch n ica l d evelop m e nts in o ffsh o re fish farm ing.
A tla n tic salm on farm ing is dom inated by N orw ay. S cotland and Ireland are also m ajor p ro d u c e rs . O th e r p ro d u c e rs in clu d e C hile, C anada, A u stra lia , Faroe Islands, and Iceland.
At th e end o f th e 7 0 s , about 20 000 to n s of salm on have bee n p roduced by a q uacu lture and up to 360 0 00 to n s are fo recast by the y e a r 2000.
The need to move offshore
T hree strong m otivations fo r offshore fish farm ing:
• U rban and industrial pollution has prevented the develop m e nt of inshore fish farm s. In som e areas, there a re sim ply no more suitable o r u n d e ve lo p e d sites.
• T he strong pressure to preserve th e rem aining m angroves and coral reefs. (See also the im pact of seafarm ing, th is issue.)
• T he potential p rofitability o f offshore farm ing in co u n trie s that do not have sheltered coasts but have suitable w a te r quality.
A prototype offshore cage system built by a Scottish shipyard. For further informa
tion, contact: Campbeltown Developments Ltd., Trench Point, Campbeltown, Argyll PA 28 6EP. Fax: +44 586 552 728.
Source: Fishfarm ing International, Aug 1993.
16 Aqua Farm News Vol. XII (No. 1) January-February 1994
TECHNOLOGIES
The challenge
In th e m ore exposed offshore en viro n ment, the cage unit is at the m ercy o f w ind and w aves. T he cage m ust w ithstand these forces.
This is not in itself a difficult ta s k given the technolo gy fo r oil production at sea. Oil rigs can w ithstand the m ost extrem e condition s and there are very fe w m echanical failures. T he im portant fa c to r in offshore farm ing is the cost, w hich m ust be justified by the value o f th e fish produced. It is ap p ro p ria te technolo gy at the right price.
T he next co nsideratio n is m anagem ent.
T he ideal o ffs h o re s y s te m s h o u ld be fu lly equipped and m echanized to allow autom ation of m onitoring and control. T he e conom ics of fish farm ing do not allow helicopte r transport of staff yet!
Fully serviced system s are being eva lu ated by a N orw egian com pany. T he system has its o w n a c c o m m o d a tio n , p o w er, a u to m a te d feeding system , and equipm en t fo r m echanical grading, harvesting and off-loading of fish. T he steel structure is 126 x 32 m eters w ide, w ith a total volum e of 25 000 m 3. A nn u a l production is estim ated at 500-700 tons.
O ther con ce p ts include a “m other” p la t
form , containing all support services, surrounded by subm ersible “s a te llite ” production units. The culture units are protected from w aves and w ind and could even a llow a quacu lture under ice in A tlantic C anada, fo r exam ple.
Finally, th e effect o f the o ffshore en viro n ment on the fish m ust be studied. M ore exposed condition s m ay cause stress o r d am age to stock.
What of the future?
The potential fo r offshore fish farm ing is enorm ous. H ow ever, it is costly, and can th e re fore happen only in buoyant m arkets. T he m arket fo r farm ed fish m ay o r m ay not continue to grow at its present rem arkable rate. But, under the right circu m sta n ce s, o ffsh o re fish farm ing will d ra m a tica lly increase m arine fish production fro m aquaculture.
Source: C Clarke and M Beveridge. O ffshore fish farming. INFOFISH International 3/89.
SEA RANCHING
To im p ro v e p r o d u c tiv ity , aquaculture development will involve the dispersal of 50% o f governm ent- produced milkfish and shrimp to the open sea.
- Philippine Department of Agriculture Medium-term Development Plan
M igratory fish species such as salm onids have long been ranched in the w estern U SA and in Japan. W ith th e em ergence of cheap m ass-produced seed, sea ranching of o ther sp e cie s has been tried - red sea bream and kurum a shrim p (P enaeu s ja p o n ic u s) in Japan, tig e r shrim p in T aiw an, and Trochus and the giant clam s in several Pacific Island countries.
Japan releases 2/3 of all hatchery raised kurum a shrim p in open w a te rs - about 6 00 m illion fry a year.
In PR C hina, th e g overnm en t has released a rtific ia lly h a tc h e d ju v e n ile m arine shrim p (P enaeus o rie n ta lis) in the open sea. In 1986, m ore than 4 billion ju veniles w ere released in the Pohai Sea and the Y e llo w S ea at a cost of about U S$4 m illion. T he recapture rate w a s 4.6-8.2% . T his am o u n te d to 4800 to n s with a va lu e of U S$24 m illion in 1986.
In the Philippines, the governm en t plans to disp e rse m ilkfish and shrim p.
S E A F D E C /A Q D a ls o p la n s th e se a ranching of reef fish e s off M alalison in w estern Panay. S n a p p e r ju v e n ile s w ill be te st-released in th e artificial reefs that w ill be d e ploye d around the island.
S to c k e n h a n c e m e n t of th e a b a lo n e H aliotis a sinina is also planned in d e pleted areas.
Sources: (1) I Csavas: Recent developments in coastal aquaculture In the Asia-Pacific. INFOFISH In
ternational. 4/89. (2) YC Shang. Marine shrimp farming in PR China. INFOFISH International. 2/89. (3) 1992- 1993 Report of SEAFDEC Aquaculture Department.
Aqua Farm News Vol. XII (No. 1) January-February 1994 17
