1.Department of Aquaculture, National Pingtung University of Science and Technology.
2.Fish Breeding Association of the Republic of China.
3. Department of Aquaculture, National Kaohsiung Institute of Marine Technology.

The aquaculture history in Taiwan has more than three centuries, however, the marine fish seed industry has a history for not more than three decades. In 1998 there are more than 60 species of marine finfish under culture (Table 1), 90% of them are being artificially propagated. We will focus on the current status of fish seed industry of those species suitable for offshore cage culture such as grouper, sea bream, snapper, great yellowtail, and sergeantfish, etc. The methods of transporting fingerlings from hatchery to sea cages, and the mid-term growing of fingerlings in sea cages will be also presented.

The aquaculture history in Taiwan has more than 300 years, however, the marine fish seed industry has a history for not more than 30 years and has grown rapidly during latest decade. In 1998, there are 64 species of marine finfish under culture, 90% of them are being artificially propagated. (Table 1). It is not until 1973 was the artificial propagation of grey mullet (Mugil cephalus) succeeded, which laying the keystone of the development of the marine finfish larviculture in Taiwan (Liao et al., 1973). Partly with the high demand and the high profit of marine finfish and partly with the depressed prawn industry began in 1988, many prawn producers and farmers became eagerly devoted themselves to the marine finfish seed production. The rapid development of Taiwanese offshore cage culture in recent years has further accelerated the development of marine finfish seed industry. Most Taiwanese hatchery managers raised their own broodstocks for artificial propagation. It is because broodstocks are rarely caught in the wild and are not available from commercial growout ponds. For the purpose of multi-channel management and livelihood, these hatcheries have bred at least 2 species of fish seed (FBA, 1998). In addition, these hatcheries have evolved into a very efficient and organized sub-business with the marine finfish culture industry (Fig. 1). In order to promote Taiwan as the Asian-Pacific fish seed supply center and to export high quality fish seed to Asian-Pacific region, the Fish Breeding Association (FBA) of Republic of China (R.O.C.) was founded in May 1996. Currently, the association has 776 members of local hatchery managers. It is estimated that over 2000 hatcheries are operated in Taiwan by 1997. According to the Fisheries Yearbook in Taiwan area in 1997, the total freshwater and marine finfish seeds production is 1500 million (valued at 70.6 million US$), the shrimp seeds was produced 3622.9 million (10.4 million US$), the soft shell turtle and crab juveniles was 35.3 million (8.4 million US$), and the small abalone seeds reached 185.6 million (15.1 million US$) (Anon., 1998). Because of the heavy rainfall, it is expected that the marine finfish seed production in 1998 will be relatively decreased as compared to 1997. The shell fish seeds was recorded 1227 metric tons (1.2 million US$). This paper briefs the current status of Taiwanese marine finfish seed industry, which deriving and revising from published literatures (Liao, 1993; 1997; Liao et al., 1995; Kuo, 1995) as well as field surveys from the FBA R.O.C. (FBA, 1998). The major species suitable for offshore cage culture such as grouper, sea bream, great yellowtail and sergeantfish are selected and discussed. Other species of interest include seabass and pompano, etc. The live seed transport and mid-term growing of fingerlings in sea cage are also introduced.

1. Grouper and red drum

Groupers are considered the best-eating table fish and the most highly priced fish in Taiwan. Among the 52 species found in waters off Taiwan, the target species for artificial breeding are the malabar grouper (Epinephelus malabaricus), red-spotted grouper (E. coioides), green grouper (E. tauvina), giant grouper (E. lanceolatus), and highfin grouper (Cromileptes altivelis) (Tang et al., 1979a; Tseng and Ho, 1979; Lin et al., 1988a; Chu, 1993; Huang et al., 1994; Liao et al., 1995; Wang, 1997). The grouper seed sources are partly bred and reared in local hatcheries and partly imported form Southeast Asian countries, i.e. wild-caught fry. With better survival and growth rates than wild-caught fry, hatchery-reared fry are preferred by local fish farmers. To meet the needs and demands of domestic consumers and aquafarmers, the local researchers and private hatchery producers have been incessantly working on the artificial breeding and culture techniques for new species with aquaculture potential (Huang et al., 1986; Lin et al., 1987; 1988;Yeh and Ting, 1990; Yeh et al., 1991; Yeh et al., 1995). In 1997, there are ten largest grouper broodstock farmers located in southern Taiwan (Chu, 1998). They can produce 20 billion of fertilized grouper eggs providing more than 1000 grouper hatcheries for their annual demand. These hatcheries yield about 20 million of grouper seed. The prices for the fertilized eggs was once reached US$ 3000-6000/kg and then dropped to US$ 600-1200/kg. The local seed (~3.0 cm) price was from US$ 1.2-1.5/fry to US$ 0.4-0.8/fry depending on the market demand and the production (Table 2). In 1997 (Anon., 1998), the grouper seed production is 26.5 million (3.6 million US$). A very efficient and organized sub-business of the grouper seed industry is shown on Fig. 1. Since 1988, the grass prawn (Penaeus monodon) culture industry is depressed owing to the prevailing of vibrio and viruses disease. Lots of hatcheries were converted their farms for grouper seed production, so called indoor system. The average production is 150-250 thousands/30-50 tons tank/crop (30-40 days). The grouper larvae were fed with shrimp flake, microparticulate feeds, oyster embryos, nauplii and adult. Some hatchery farmers often add the green microalgae (Nannochloropsis sp.) to larval rearing tanks to control water quality and transparency. Furthermore, mass fertilized eggs produced from the outdoor broodstock farms had initiated the outdoor system. The survival rate of outdoor system was lower than indoor one. When applying the indoor system to outdoor one, the larvae’s survival rate increased. With this method, the average seed production is 0.5 million/ 3000m2/crop. Red drum (Sciaenops ocellatus) was introduced from Texas, U.S.A. to Taiwan in May 1987 and then spontaneously spawned in September 1991 (Liao et al, 1994). The survival rate was below 5% in 1991 as compared to > 30% now. The artificial propagation of red drum has been fully developed. The red drum seed production was 30 million in 1997 (FBA, 1998) and its price was between US$ 0.01-0.02 per seed (Table 2). This fish grows fairly at the 1st year (250-900 g) and rapidly at the 2nd year (750-2300 g) and 3rd year (1700-4700 g).

2. Sea bream

There are 10 species of sea bream found in waters around Taiwan. The four most important species under culture are red sea bream (Pagrus major), black sea bream (Acanthopagrus schlegeli), yellowfin sea breem (A. latus) and silver bream (Sparus sarba) (Table 1). The artificial propagation and mass seed production techniques of these species are fully developed (Lin et al, 1979; Tang et al., 1979b; 1979c; Lin et al., 1987a, 1987b; Lin et al., 1988b; Liu and Hu, 1980; Yen, 1988). In 1997, the seed production of sea bream is 15 million (40 hatcheries) of black sea bream, 10 million (31 htacheries) of yellowfin sea breem, 10 million (38hatcheries) of silver bream, 1.5 million (20 hatcheries) of red sea bream (Table 2). The price of fish seed ranged from US$ 0.03-0.4/seed depending on species, market demand and production. Due to the overproduction of sea bream seeds in recent years, it is expected that the foreign markets should be developed and extended.

3. Snapper

Among 43 species of snapper (Lutjanus spp. & Lethrinus sp.) found around Taiwan, there are only 7 species under culture (Table 1). The artificial breeding of mangrove red snapper (L. argentimaculatus) was firstly recorded in 1984 by one of the private hatchery in southern Taiwan. Mass production of fertilized eggs were commenced in 1990 (Chang, 1993b). In an uncovered outdoor pond systems, mass fertilized eggs were stocked directly into the pond. While in an indoor system, it usually takes 30-40 days for the fish to attain 2.5 cm in total length. The major feeds are Acetes chinensis and chopped trash fish. The reared fries are also acclimated to floating or moist pellets. The seed production in 1997 includes 30 million (48 hatcheries) of mangrove red snapper, 15 million (6 hatcheries) of pink snapper (Lutjanus erythropterus), 2.5 million (20 hatcheries) of green snapper (Lethrinus miniatus) and 1 million (1 hatchery) of white-spotted snapper (L. stellatus) (Table 2). The unit price ranges US$ 0.15-0.8 depending on the species, demand and production.

4. Great yellowtail (Seriola dumerilli)

Since there is no domestic artificial bred seed, the wild-caught great yellowtail fries are mainly imported from Hanhai Province, southern mainland China. With a maximum size of 1.5-2 m, this fish can grow to 1 kg at the first year in sea cage and reach 5-7 kg at the second year. The major feed are trash fish. The local feed companies are still working on the development of artificial feed to replace the trash fish. In 1997, there are 1.4 million of wild-caught fry transferred from mainland China and growed in the sea cages (FBA, 1998). The fry (2.5-3.0 cm) price was once high (1-1.5 US$ per seed) and then dropped to 0.4-1.0 US$ per fry in 1997 (Table 2). The large size fry (10-12 cm) costs US$ 2.9-4.5 each.

5. Cobia or sergeantfish (Rachycentron canadum)

The seed-stock production techniques of cobia was firstly developed in 1995 by the Yung Hsing Fishery Breed Farm, a private hatchery in Lin-Peng Hsiang, southern Taiwan. Like great yellowtail, cobia can grow to 5-6 kg at the second year in cage. Although the market size is about 80 cm, cobia can grow to 2 m in maximum. It is one of the most favorable species in the domestic offshore cage culture. The major feed are trash fish and artificial feed, i.e. dry or moist pellet. In 1997, 1.4 million of sergeant fish seed were produced by 4 hatcheries (Table 2). Its price ranged from US$ 0.4 to 0.6/seed.

6. Sea bass

The Japanese sea bass (Lateolabrax japonicus) and Asian sea bass (Lates calcarifer) is one of the target species culturing both in Taiwan and southeast Asian countries. These fish was once polycultured with tilapia to maintain the appropriate number of tilapia. Since sea bass can spawned naturally in the ponds, it is seldom performed the artificial propagation to produce seed. The major feed are green algae, rotifer, artemia, copepod, artificial feed, etc. In 1997, there are 5 hatcheries producing 11.8 million of Japanese sea bass seed (Table 2). Due to the low market price, there is only one hatchery producing 100 thousands of Asian sea bass fry in 1997. The price of the sea bass seed was US$ 0.1-0.4 per seed.

7. Snub-nose pompano (Trachinotus blochii)

The pompano is one of the popular species culturing by the local aquafarmers. It often takes three years for the fish to be sexually matured. The artificial propagation techniques is fully developed by one of the private hatchery manager in 1989 (Cheng 1990; Chang, 1993a). Because of the fish’s tasty meat, fast growth rate and appealing appearance, the pompano culture industry has been developed very quickly in this decade. Those fry produced during spring and summer are poured into the growout ponds. Fry produced in autumn are cast in the nursery for overwintering. The prime feed for the larvae are rotifer, artificial feed, copepod. In 1997, there are 20 hatcheries produced 38 million of fry (Table 2). The fry price is between US$ 0.04-0.09/seed. If this fish can be stocked in sea cages, it will soon become a profit-industry.

8. Other species

Mass seed production of other marine finfish species in 1997 include 4 million (6 hatcheries) of three-banded grunt (Plectorhynchus cinctus), 1 million (12 hatcheries) of lined silver grunter (Pomadasys kaakan), 500 thousand (7 hatcheries) of narrow-banded batfish (Platax orbicularis), etc (Table 2). The unit price is US$ 0.2-0.8 for three-banded grunt and US$ 0.4-0.5 for narrow-banded batfish. The candidates with cage culture potential include large yellow croaker (Pseudosciaena crocea), brown croaker (Miichthys miiuy), tiger grouper (E. fuscoguttatus), potato grouper (E. tukula), drum fish (Nibea spp.), emperor snapper (L. sebae), and grunt (Plectorhynchus spp.) etc (Table 1).

The Taiwanese experience on the domestic live fish seed transport can be summarized as Fig. 2. A successful of seed transport from hatchery to sea cage depends on species/size of the fry and the distance between the hatchery and the cage. The seed must stop feeding at least 24 hours prior to transport. The ways of transporting seed from hatchery to the wharf are live seed carrier (long distance) or plastic bag packing (short distance). Prior to seed transport, appropriated water temperature, dissolved oxygen content, stocking density and the fresh water exchange during the transport are to be considered. The live seed boat is used to transfer seed from wharf to sea cage. The use of anesthetics (MS-222, Urethan and 2-methyl-quinoline) may be needed to decrease the metabolism and moment of the seed while transport. The best time to transport seed is at night. The foreign live seed transport is abstracted in Fig. 3 and will be briefed at the workshop.

In the past time, most cage farmers purchase fish seed (2.5-3.0 cm) from local hatcheries and reared them in a small cage (3¡Ñ3¡Ñ3m) to 9-12 cm. They are then transferred to a larger cage (6¡Ñ6¡Ñ8m or 10¡Ñ10¡Ñ10m) and kept rearing them to market size. After many years of field practice, cage farmers find out it would be much easier to manage and maintain the fries if they purchase them with same (grading) size and in good quality from large fry producers . After acclimated to the artificial feed and attaining to market size (9-10 cm), they will be transferred into the cage via live fish carrier (15 tons) or live fish boat (30-50 tons).

The authors wish to thank the staffs at FBA, R.O.C. Special thanks go to Mr. K. H. Yu, supervisor at FBA and anonymous hatchery managers in southern Taiwan. Without their help and providing information, this paper could otherwise be accomplished.

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Table 1. The current culture mairne finfish species in Taiwan (adapted and revised from Liao et al., 1997; FBA, 1998).

Table 2. The present status of the Taiwanese marine finfish seed industry in 1997 (FBA, 1998).

Table 3. The current status of Taiwanese sea cages in 1997.

* ; start to stock fish seed in 1998 or October 1997. ** ; stop operation in 1998. a; imported from Norway. b; domestic made circular cage. c; octagonal cage, domestic made. d; imported from Denmark. d; the grand total is 3072, after adding those 29 cages not for culture purpose. dia.; diameter (m) of circular cage.