Key words: sustainable aquaculture, integrated coastal zone management (ICZM), Taiwan
Taiwan is located on the western edge of the Pacific Ocean. Separated from mainland China by the Taiwan Strait, Taiwan is bordered by the South China Sea in the south, the East China Sea in the north, and the Pacific Ocean in the east. Located in the Tropic of Cancer, Taiwan has a subtropical climate except its southern part, which is tropical. Average temperature on the lowlands range from 16Â°C to 18Â°C in January to (27-29)Â°C in July. Sea surface temperatures of coastal waters vary from 20Â°C to 22Â°C in winter (December to February) to (28-30)Â°C in summer (June to August) ( Fig. 1(840)). The natural environmental conditions in Taiwan are suitable for the development of aquaculture.
Coastal aquaculture in Taiwan can be traced back to the milk fish culture 400 years ago (Ling 1977). After continuous development, a standard year-long operation system for the shallow brackish-water pond culture has been developed. Traditionally, milk fish culture has played an important role in the socioeconomic development of coastal communities in the southwestern part of Taiwan. With the success of artificial propagation of grass prawn in 1968 (Liao et al. 1969), prawn farming emerged as a fast growing industry in the coastal zones. The resulting high prawn production placed Taiwan on the map in the 1980s as one of the leading prawn producing countries in the world (Fast et al. 1989). However, the disease outbreaks caused the collapse of the industry in 1988 (Liao 1989). Currently, groupers, milk fish, white shrimp, hard clam, black sea breams and sea bass are the major species reared in the brackish-water ponds. As to mariculture, oyster farming significantly contributes to the livelihood of coastal communities. Recently, marine cage aquaculture is getting popular in Taiwan, and cobia is regarded as the best species for commercial marine cage culture (Su et al. 2000).
Coastal zones are intensively used for transportation, fishing, aquaculture, recreation, waste disposal, power generation, water supply, forestry, residential and industrial purposes. Furthermore, coastal zones are buffer zones against the ravages of rough waves, flooding, and erosion. Coastal zones must be managed in an integrated manner to ensure harmonious and sustainable development for all sectors in the coastal zones. This paper discusses the status of coastal aquaculture in Taiwan, related problems and solutions, and recent research and development activities toward sustainable coastal aquaculture.
Production of Capture Fisheries and Aquaculture
The fishery industry in Taiwan can be categorized into far sea fishery, offshore fishery, coastal fishery, and aquaculture. Far sea fishery refers to those fishing activities performed beyond the 200-mile exclusive economic zone of Taiwan. Offshore fishery refers to those fishing activities conducted within the exclusive economic zone extending from 12 to 200 miles from the baseline. Those operated within the 12-mile territorial sea of Taiwan are referred to as coastal fishery. Aquaculture includes freshwater culture, brackish-water culture and mariculture. Combined, brackish-water culture and mariculture are called coastal aquaculture. The production analyses in this paper are based on the statistical data released by the Fishery Agency (2008).
Annual fishery production in terms of quantity and value by types of fishery from 1987 to 2006 varied ( Fig. 2(721)). During this period, total fishery production appeared fluctuating from 1.2 million to 1.5 million mt valued at NT$83 billion to 100 billion. Coastal aquaculture production was 100-150 thousand mt valued at NT$10-18 billion. In 2006, total fishery production was 1,266,026 mt valued at NT$85,369,935,000. Of this figure, far sea fishery, offshore and coastal fishery, coastal aquaculture, and inland freshwater aquaculture contributed 59%, 17%, 11% and 13% to the total production, respectively ( Fig. 3(692)). This is valued at 49%, 18%, 13% and 20%, respectively ( Fig. 4(742)).
Major Cultured Species
The major cultured species, which accounted for over 90% of total aquaculture production, were tilapia (hybrids of Tilapia spp.), milk fish (Chanos chanos), hard clam (Meretrix lusoria), Japanese eel (Anguilla japonica), oyster (Crassostrea gigas), freshwater clam (Corbicula fluminea), groupers (Epinephelus malabaricus, E. coioides, E. lanceolatus and E. fuscoguttatus), white shrimp (Litopenaeus vannamei), giant freshwater prawn (Macrobrachium rosenbergii), gracilar (Gracilaria spp.), sea bass (Lates calcarifer, Lateolbrax japonicus, Bidyanus bidyanus, Micropterus salmoides, etc.), sea breams (Pagrus major and Acanthopagrus schlegeli ) and cobia (Rachycentron canadum) ( Fig. 5(778)). Combined production of tilapia, milk fish and hard clam was 53.57% of total aquaculture production.
On the other hand, the major culture species, which was over 90% of total aquaculture production value, were Japanese eel, giant freshwater prawn, oyster, tilapias, milk fish, groupers, white shrimp, hard clam, sea breams, cobia, small abalone (Haliotis diversicolor), freshwater clam, soft-shelled turtle (Trionyx sinensis) and sea bass ( Fig. 6(761)). Production value of combined Japanese eel, giant freshwater prawn, oyster and tilapias was 54.3% of the total aquaculture production.
Fig. 7(719) presents annual average farm-gate prices for selected species from 1993 to 2006. The price of small abalone was higher than other species at NT$380-650/kg. Prices of Japanese eel, red sea bream and giant freshwater prawn were NT$200-400/kg. Price range of groupers, white shrimp, cobia and black sea bream was NT$150-200/kg. Milk fish, tilapias and hard clam had the lowest price of NT$30-60/kg.
Milk fish is an important cultured species in the southwestern part of Taiwan. For a long time, unstable supply of fry had hindered the development of milk fish culture. Since the success of artificial propagation of this species in Taiwan in 1984 (Lin 1985), the fry production has increased significantly. The hatchery fry not only provided milk fish farmers of Taiwan with ample supply, but also were exported to several Southeast Asian countries.
Two systems are used to culture milk fish in Taiwan: shallow-water culture and deep-water culture. Shallow-water culture is the traditional culture system, which usually uses brackish-water ponds. The management of the system involves pond preparation, stocking fry or fingerling, pond management, selective harvesting and over-wintering. The deep-water system, which uses freshwater ponds, was developed in the mid 1970s. The procedures for the deep-water method are pond preparation, fry stocking, harvesting and over-wintering. As with shallow-water systems, milk fish weighing 500 g or more are thinned out selectively with gill nets. Harvesting begins in August and thereafter depending on the fish growth. Final harvest takes place in November before winter. The deep-water milk fish culture yields 8,000 kg /ha to as high as 120,000 kg/ha per year.
Fig. 8(809) shows the annual production of milk fish in Taiwan from 1993 to 2006. Total production fluctuated from 36,000 to 78,000 mt valued at NT$1.9 million to 3.6 million. Peak production quantity occurred around 2002-2004. However, peak production value occurred around 1995-1996. The production from freshwater ponds was larger than that of brackish-water ponds.
The major areas for development of this species are: (1) development of innovative strategies for shallow brackish-water pond culture to reduce fish loss in winter; (2) development of technologies for fattening fish to upgrade fish EPA and DHA levels to increase its commercial value; and (3) improvement of feed formulation and processing using more gradients from algae to decrease culture cost and improve fish quality.
Grouper culture in Taiwan began in the early 1970s and the grow-out wild-caught fry was from either Taiwan or Southeast Asian countries. Full-life-cycle culture of E. coioides and E. malabaricus was achieved in the early 1980s. Currently, the most popular culture species are E. coioides, E. malabaricus, E. lanceolatus and E. fuscoguttatus. In 2006, 46.8 million fry of E. coioides and E. malabaricu, 5.04 million fry of E. lanceolatus and 4.7 million fry of E. fuscoguttatus were produced. The fishes were mainly raised in brackish-water ponds using dry or moist formulated pellet feeds.
Fig. 9(698) shows the annual production of groupers in Taiwan from 1993 to 2006. Total production volume was 1,800-3,400 mt in 1993-1998 and 4,100-5,300 mt in 1999-2001. It greatly increased to about 12,400 mt in 2002, maintained at 11,500-13,600 mt in 2003-2005, and then dropped to about 9,300 mt in 2006. Total production value was less than NT$900 million in 1993-1998 and it increased to NT$1.081 million to 1.218 million in 1999-2001. The production value significantly increased to about NT$1.897 million in 2002, maintained at NT$2.272 billion 2,272,000 to NT$2.688 billion in 2003-2005, but dropped to about NT$1.73 billion in 2006. Production from brackish-water ponds dominated the whole industry.
The major areas for development of this species are: (1) establishment of SPF broodstocks to cut transmission of pathogens in groupers; (2) improvement of larval rearing and nursery systems to upgrade the production of healthy juveniles for grow-out; and (3) development of vaccines to curb viral diseases of groupers.
Specific pathogen free (SPF) breeders of white shrimp from Hawaii, USA have been imported to Taiwan since 1996. Since then, white shrimp culture has become an important business in Taiwan. To develop technologies for mass production of SPF white shrimp fry, Tungkang Biotechnology Research Center (TBRC), Fisheries Research Institute (FRI), and Council of Agriculture (COA) have established the PCR techniques for monitoring viral diseases of shrimp and developed the hatchery system for mass production of healthy fry. The production of white shrimp culture in Taiwan increased from 2,310 mt in 2000 to 10,361 mt in 2006, valued at NT$5.06 million in 2000 to NT$1.8 million in 2006 ( Fig. 10(761)).
The major areas for development of this species are: (1) development of a biosecure system for SPF shrimp culture to prevent diseases; (2) enhancement of genetic studies on white shrimp to increase its growth and disease resistance; and (3) development of an appropriate monitoring system to evaluate ecological impact of white shrimp.
Japan introduced the aquaculture of hard clam to Taiwan in 1925. Hard clam was extensively ranched in sandy tidal flats. To control water quality, hard clam is now mainly cultured in brackish-water ponds, especially in the west coast. After the mass artificial fry production (Chen and Lyuu 1982), annual production increased by 88% from 9,200 mt in 1982 to 17,322 mt in 1984 (Chien and Hsu 2006). The annual production was 17,849 - 30,711 mt, valued at NT$ 678 million, to 1.2 million in 1993-2005, and increased significantly to 49,186 mt valued at NT$ 1.6 billion in 2006 ( Fig. 11(739)).
The major ares for development of this species are: (1) improvement of pond management of hard clam culture to increase its productivity and product's quality; (2) development of fattening technologies to increase hard clams quality and commercial value; and (3) enhancement of genetic studies of hard clam to increase its growth performance and disease resistance.
Oyster culture is the most traditional shallow sea farming in the western coast of Taiwan. Oyster seeds are collected from the wild. Spot collection is conducted in November to February and July to August. Methods of oyster culture practiced in Taiwan include bamboo stick, hanging, suspension, long-line, and raft methods. Fig. 12(695) shows annual production from 1993 to 2006. The production from 1998 to 2002 was around 20,000 mt, while that of other years was maintained at higher level of 25,000 mt. Production in 2006 reached 28,547 mt, valued at NT$3.03 billion.
The major areas for development of this species are: (1) investigation of physical, chemical and biological conditions of farming grounds; (2) improvement of spot collection and cultural management; and (3) establishment of mass production of artificial seed to reduce dependence on wild spot.
Cobia is now popularly cultured in marine cages in Taiwan. Its fast growth rate, good meat quality, and high market price make it popular among cage farmers (Shiau 1999; Su et al. 2000). Since 1999, the production of cobia has been steadily increasing, except in 2002 and 2006 where production declined due to typhoons, cold wave and disease outbreaks. Production in 2006 was 2,914 mt, valued at NT$599 million ( Fig. 13(704)).
The major areas for development of this species are: (1) promotion of step-wise culture to diversify culture methods; (2) development of cage systems to reduce risks of loss in typhoon and cold current; (3) improvement of feeds and feeding facilities to reduce production cost; and (4) to development of vaccines to prevent diseases.
Examples of Recent R&Amp;D toward Sustainable Aquaculture
Establishment of the National Aquatic Genetic Resources Center
Better management and conservation of important aquatic genetic resources towards sustainable aquaculture has been the focus in Taiwan in recent years. The FRI, COA has launched a project to establish the National Aquatic Genetic Resources Center since 2001. It was planned to construct genetic resources facilities at four research centers of FRI, namely, the Freshwater Aquaculture Research Center (FARC), Tungkang Biotechnology Research Center (TBRC), Eastern Marine Biology Research Center (EMBRC), and Penghu Marine Biology Research Center (PMBRC). The facilities at FARC and PMBRC were completed in 2006 ( Fig. 14(842) & Fig. 15(805)). Selected aquatic organisms of genetic importance are conserved in indoor ponds. The center is operated following the procedure shown in Fig. 16(793).
Establishment of Traceability System for Aqua-Product
The COA has established Taiwan agriculture and food traceability system, including Taiwan good agricultural practice (TGAP), information management and traceability, the candor third-party certification system (COA, 2007). Currently, the system has been implemented for 14 cultured species covering Japanese eel, tilapia, grouper, milk fish, cobia, pompano, sweet fish, sea bass, grey mullet, white shrimp, freshwater prawn, hard clam, freshwater clam, and oyster.
Development of Technologies for Complete Utilization of Fish Scales
Fish scales are wastes of fish processing. Recently, the FRI has successfully developed a technology that extracts useful components from fish scales with high production rate and purity and low pollution. The fish scale is mainly composed of collagen and hydroxyapatide. The collagen is one of the most important structural fibrous proteins in connective tissue of human body, which has the ability to activate cells, heal wound and repair tissue. It also can make the skin elastic and can induce face-lift. The hydroxyapatide can be a biomaterial for orthopedics and dentistry, and a nutrient supplement to prevent osteoporosis. The fish scale, a rarely utilized substance in the industry, when treated with extraction technology can produce collagen peptide and hydroxyapatide.
Development of Technologies for Complete Utilization of Oyster Shell
Oyster shells are often causing environmental problems in the coastal communities. The extracting techniques of "pearl layer extracts" and "calcium oxide" from discarded oyster shells have been established by FRI. Both techniques do not use any organic or chemical solvent, hence, it is safe for cosmetic use. "Pearl layer extract" shows strong inhibitory activities for tyrosinase. It is also applied to culture medium for skin melanin cells, which shows no cytotoxicity and reduces the production of melanin. Besides, it is effective as antioxidant materials. The component of oyster shell changes from CaCO3 to CaO by heating, and in this process, the heavy metal existing in CaCO3 is driven out. An advantage of CaO is that it is easily soluble in hydrochloric acid in gastric juice and would not have the plenitude.
Establishment of Biosecure Culture System for SPF Penaeid Shrimps
To promote healthy shrimp aquaculture, the TBRC has successfully developed technological platforms for monitoring viral diseases with PCR techniques for each growing stages to ensure successful maintenance of SPF shrimp stock. The establishment of selective breeding programs through either traditional method or advance molecular method on penaeid shrimps is to produce superior strains with high performances in reproduction and growth, and resistant in diseases and stress. The effective and economic feasible biosecure system can ensure high survival during culture period with high density and high yield.
Development of Technological Platform for Healthy Grouper FRY Production
In recent years, nervous necrosis virus (NNV) and Taiwan grouper iridovirus (TGIV) have caused heavy mortality of grouper in larviculture. The transmission of virus is considered to be both horizontal and vertical infection. Thus, groupers from egg to larvae are all vulnerable to virus diseases. To produce healthy larvae for culture, the Mariculture Research Center (MRC), FRI is carrying out an integrated project aimed to establish virus-free broodstocks and to produce virus-free fertilized egg, fry and juveniles.
Development of Technologies for Macroalgae Forestation
Macroalgae are keys to the prosperity of marine resources. Forestation of macroalgae at adequate sites would provide habitats for brooding, inhabitation, reproduction and feeding to marine organisms. Meanwhile, macroalgae can also absorb carbon dioxide to mitigate global warming. Polysaccharides extracted from them can be fermented to alcohol for biomass energy and used for food and other commodities. A pilot project of macroalgae forestation in Penghu waters is being conducted by PMBRC.
The Way Forward
Planning and regulatory frameworks for the strategic and controlled development of the coastal zones should be formulated. The development of coastal aquaculture should be based on the principles of biodiversity conservation and sustainable use of natural resources. More scientific and socioeconomic studies are required to address the constraints that are currently limiting the performance of both the brackish-water culture and mariculture. The needed major actions are recommended as follows:
- Promote Integrated Coastal Zone Manage-ment (ICZM) to improve environment for good aquacultural practices.
- Strengthen assessment and communication of environmental risks in coastal aquaculture based on GESAMP (2008).
- Reduce the use of chemicals and antibiotics.
- Strengthen research on culture of herbivorous species to reduce the use of fish meal.
- Strengthen research on vaccine development for groupers and cobia.
- Develop value-added products on hard clam and milk fish.
- Refine laws and regulations related to coastal aquaculture.
- Develop typhoon-proof offshore cage culture systems to prevent disaster loss.
- Strengthen research on replanning of coastal aquaculture lands and designing of innovative eco-friendly aquacultural farms to prevent or reduce losses caused by nature disasters.
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- GESAMP (IMO/FAO/UNESCO-IOC/UNIDO/WMO/IAEA/UN/UNEP Joint Group of Experts on Scientific Aspects of Marine Environmental Protection) (2008). Assessment and communication of environmental risks in coastal aquaculture. Rome, FAO. Reports and Studies GESAMP No. 76: 198 pp.
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- Ling, S.W. (1977). Aquaculture in Southeast Asia: A historical view. 108pp. Univ. of Washington Press, Seattle Washington.
- Su, M.S., Chien, Y.H., Liao, I.C.(2000). Potential of marine cage aquaculture in Taiwan: cobia culture. In: Liao, I.C., Lin, C.K. (Eds.), Cage Aquaculture in Asia. Asian Fisheries Society, Manila, and World Aquaculture Society-Southeast Asian Chapter, Bangkok, 97_106.
- Shiau, C. Y. (1999). Chemical and nutrient composition of cultured cobia (Rachycentron canadum). Project Report of Taiwan Fisheries Bureau 1999. Taiwan Fisheries Bureau, Taipei, Taiwan, 24 pp.
Index of Images
Figure 1 Map Showing Seasonal Mean Sea Surface Temperatures and Currents in the Waters Surrounding Taiwan.
Figure 2 Annual Capture Fisheries and Aquaculture Production in Taiwan from 1987 to 2006.
Figure 3 Fisheries and Aquaculture Production (MT) of Taiwan in 2006.
Figure 4 Fisheries and Aquaculture Production Value (Thousand NT$) of Taiwan in 2006.
Figure 5 Major Cultured Species Accounted for Over 90% of Total Aquaculture Production by Quantity in Taiwan on the Average of 2002-2006.
Figure 6 Major Cultured Species/Groups Accounted for Over 90% of Total Aquaculture Production by Value in Taiwan on the Average of 2002-2006.
Figure 7 Annual Average Prices of Major Cultured Species in Taiwan from 1993-2006.
Figure 8 Annual Aquaculture Production of Milkfish in Taiwan, 1993-2006.
Figure 9 Annual Production of Groupers in Taiwan, 1993-2006.
Figure 10 Annual Aquaculture Production of White Shrimp in Taiwan, 2000-2006.
Figure 11 Annual Aquaculture Production of Hard Clam in Taiwan, 1993-2006.
Figure 12 Annual Aquaculture Production of Oyster in Taiwan, 1993-2006.
Figure 13 Annual Aquaculture Production of Cobia in Taiwan, 1993-2006.
Figure 14 Facilities of the National Aquatic Genetic Research Center at PMBRC,Fri.
Figure 15 Facilities of the National Aquatic Genetic Research Center at Farc, Fri.
Figure 16 Flow Chart of Aquatic Genetic Resources Management and Conservation at the Aquatic Genetic Resources Center of Fisheries Research Institute, Council of Agriculture (Coa).
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