Volume XIX No. 1 March 1997 ISSN 0115-4974 Indonesia is new SEAFDEC Member With Indonesia as 8th member, SEAFDEC strengthens its presence in Southeast Asia as it keeps in step with the growth of the fishery industry

he Indonesian government has been officially advised of its admission to SEAFDEC and has been asked to Taccomplish the instrument of accession for submission to the SEAFDEC Secretariat. This was announced at the Twenty- ninth Meeting of the Council of the Southeast Asian Fisheries Development Center in Hanoi, Viet Nam on 4-7 March 1997. Indonesia is the eighth member of the official SEAFDEC . Cambodia has also expressed interest to join SEAFDEC. This expansion has been facilitated by A hatchery rearing method ...to page 10

Inside for the red snapper

In an AQD paper published in the Israeli Journal of Aquaculture- Read ourANNOUNCEMENT B a m id g e h the growth and survival of the red snapper larvae were on page 12 on the merging of our studied at different feeding densities and frequencies using the live two publications fo o d Brachionus, Artemia, and minced trash fish Use of chemicals in aquaculture, a requested reprint 6 In 1992, AQD reported the successful reliable spawning and hatchery tech­ niques have been one of the many SEAFDEC/AQD News 8 spawning of the Lutjanus argentimaculatus at its research thrusts of AQD. Identified as a New AQD Proceedings 12 Tigbauan Main Station. Since then, high value food fish in Hong Kong, AQD research publications 12 ...to page 2 Singapore, and Taiwan, and to some prospects year round provided import­ juveniles to meet the demand for live extent Hawaii and the US west coast, ers are assured of reliable and regular and high class fishes. the snapper industry needs to address shipments. a number of problems before it can The red snapper, Lutjanus meet these demands. These are argentimaculatus (Forsskal, 1775), is unreliable seed supply, trial-and-error distributed in the Indo-West Pacific from rearing techniques, limited information Samoa and and the Line Islands to East on market requirements, and uncom­ Africa, and from Australia northward to petitive packaging methods. Ryukyu Island, Japan. It is a marine Market information is not as wide­ also occurring in brackish spread perhaps because production estuaries and the lower reaches of has not advanced. The Food and freshwater streams. The red snapper Agriculture Organization of the United migrates offshore to deeper reef areas, Nations reported a world aquaculture sometimes penetrating to depths in production to be 18,388 metric tons in excess of 100 meters. The head profile 1993 from Hong Kong, Singapore, is straight or slightly convex. The young Malaysia, Brunei Darussalam, Nigeria, and adult have pairs of strong canines and other Asian countries. Infofish on the upper jaw. Another identification International says that as of 22 April key to the species in the Lutjanids is the 1997, prices of red snapper (all in US$) arrangement of the scale rows. In L. in Singapore are 4.40-4.80/kg for argentimaculatus, the scale rows above whole, chilled; primary wholesale in the lateral line run parallel to the dorsal New York, USA is 2.75-3.50/lb, chilled, profile over most of their length and rise fillet, eviscerated; in Miami, USA it is obliquely under the soft part of the These illustration and part description are from 2.35-4.55/lb whole, gutted, chilled; in dorsal fin which is in contrast to those of Biology and Culture of the Red Snapper, Tokyo, Japan it is 7.93-18.26/kg whole, the other lutjanids (right).The red Lutjanus argentimaculatus by Masanori Doi and shatterpack; and in France it is 4.70- snapper grows to 80-120 centimeters Tanin Singhagraiwan. 1993. The Eastern Marine Fisheries Development Center, Department of 5.20/lb fillet, skin-on, individually quick long. In recent years, coastal net cage Fisheries, Ministry of Agriculture and frozen (IQF). These markets are good culture has been developing using wild Cooperatives, Thailand.

nappers are highly valued the SEAFDEC Aquaculture Department kg) in cages at Igang, Guimaras Island. food fish in tropical were not successful. The fish were induced to with a and subtropical countries. In This paper by M.N. Duray, L.G. single injection of luteinizing Thailand, snappers are Alpasan, and C.B. Estudillo, published hormone-releasing hormone analog cultured in floating net cages in the Israeli Journal of Aquaculture- (LHRHa) at 100 µg/kg body weight. Sand ponds as alternate to sea bass and Bamidgeh 48(3), 123-132, 1996 After injection, a male-female pair was shrimps. It is necessary to develop a describes the results of later work at the placed in a hapa net cage and allowed seed production technology for the SEAFDEC AQD to develop a hatchery to spawn naturally. The hapa net was snappers in anticipation of an increased rearing method for the mangrove red slowly raised to gather the eggs which demand for juveniles. snapper. The effects of small-sized were then scooped out. Attempts to rear other species of Brachionus and Artemia nauplii at The eggs were transported to the snappers had limited success. Larval different feeding frequency and density Tigbauan Main Station hatchery in rearing of the mangrove red snapper, L. on the growth and survival of the red oxygenated double plastic bags at argentimaculatus, using Brachionus, snapper larvae are highlighted. about 300,000 eggs in 10-l sea water. Artemia, Moina and minced Each bag of eggs was incubated in had low and variable survival rates as Spawning and incubation 400-l circular fiberglass tanks with water shown by some studies abroad. Early Fertilized eggs were obtained from at 35 ppt salinity and 26-27°C and attempts to rear red snapper larvae at hormone-treated broodstock (3.6-4.3 constant aeration. Egg samples were 2 SEAFDEC Asian Aquaculture Vol. XIX No.March 1 1997 collected with a PVC pipe from five days until day 35 and every five days addition of newly hatched Artemia sections of the tank. The fertilization thereafter. nauplii. On day 25, the Artemia nauplii rate was 95%, and 62% (±14.8) were The water management and feeding were replaced by HUFA-enriched viable eggs. Aeration was stopped for a scheme is shown below. Starting on (highly unsaturated fatty acid-enriched) few minutes, dead eggs were allowed day 3, the rearing water was partially instar II Artemia to day 30. Enrichment to settle and then siphoned out. Fresh exchanged daily with fresh filtered sea was for 12 hours using self-emulsifying sea water was allowed to flow through water to maintain good water quality. lipid concentrate SELCO (Artemia for 15 min. Hatching occurred 16 hours Debris, feces, and dead fish were Systems). Chlorella was added daily at after fertilization with a mean hatching siphoned off the tank bottom every 1 -3 x 105 cells/ml as food for the rate of 57.5% (±6.2) and 65.2% (±12.4) other day. Tanks were mildly aerated Brachionus and as a water conditioner. viable larvae. throughout the rearing period. Increasing sizes of Artemia were given Brachionus plicatilis were introduced at 1-3/ml every day until day 50. On Culture of natural food on day 2 and maintained at a density of day 40, larvae were gradually weaned The green alga, Chlorella virginica, 20/ml until day 21, together with the to minced fish. was cultured in 2 7 t circular concrete ...to page 4 tanks. When the algal population reached a density of at least 10x106 cells/ml, Brachionus (S-, local Sapian, Capiz strain) were placed into the tanks at 20-50 individuals per ml. After 5-6 days, when the density was ≥120 per ml, the Brachionus was harvested using a 42 µm mesh plankton bag. Some of the harvested Brachionus was screened through 90 µm plankton netting material and used in the first feeding experiment

Larval rearing Newly hatched larvae were reared indoors in six 3 t conico-circular concrete tanks and six 500-I fiberglass tanks for 21 -24 days at a stocking density of 30 larvae/l. The water temperature was 25.5-28.7°C, the dissolved oxygen was 5.6-6.9 ppm and the salinity was 35 ppt. Twenty larvae were collected from the 3-ton tanks every three days for length measurement. For gut content analysis, 10 larvae were sampled an hour after the addition of the food, daily until day 15, and every three days till day 35. Larvae from the 500-I tanks were harvested on day 21 and restocked in 200-l tanks for feeding experiments. Water management and feeding scheme during larvae rearing Those reared in 3 t tanks were of the mangrove red snapper. harvested on day 24 and restocked at 1-3 larvae/l in nine 3 t tanks until day 55. Larvae were sampled every three

SEAFDEC Asian Aquaculture Vol. XIX No.March 1 1997 3 Previous larval rearing attempts Early attempts to rear larval red snapper to metamorphosis had limited success with survival rates ranging from zero to 43.4% on days 15 or 21. In 1993, Doi and Singhagraiwan reported a negative correlation between initial stocking density and number of harvested fry. The high mortality during the first week of this experiment agree with the observation of Doi and others. This was attributed to the poor feeding habits of red snapper larvae. Compared with rabbitfish, milkfish, and grouper, it was observed that the red snapper consumed almost all their inherent nutritional source at the onset of feeding compared to the former three species. Thus, red snapper larvae are more vulnerable to starvation during this critical feeding period. Low larvae Researchers at AQD working on red snapper seed production: Considered a survival could also be due to larvae high value food fish in tropical and subtropical countries, a seed production quality, attributable to the broodstock, technology for snappers must be developed to address the demand for its as reflected by the percentage of viable juveniles for stocking. eggs and larvae reported above. many marine fish larvae. Larvae benefit larvae is not only a function of larvae Cannibalism nutritionally either from a change in the length or mouth width but to some Cannibalism is probably one of the composition ofBrachionus or from extent is also affected by the density of causes of low survival during the partially digested algae in the guts of food available. Although Brachionus second phase of rearing. Missing fish in Brachionus. was screened using 90 µm plankton the tanks were assumed to have been netting material, Brachionus in the gut cannibalized when no dead fish were Use ofBrachionus during the first 14 days of culture siphoned out. Size differences were Although Brachionus are considered ranged from 62 to 166 µm, indicating observed. Sorting should have been to be the most suitable food organisms that excess Brachionus in the tank grew done to minimize cannibalism as for fish larvae, their size is critical for the or multiplied and were ingested by the behavioral factors contribute to survival of these small-mouthed larvae. larvae the following day. The same cannibalism among fish larvae. The mouth width of first-feeding red observation was reported by other Previous trials of red snapper rearing snapper is about 191-200 µm yet the researchers. In the absence of included feeding of small crustaceans larvae prefer much smaller prey (<105 super-small (SS) strain Brachionus, (copepods) andMoina, different or µm). Prey size selection was also screening of S -Brachionus cultures mixed phytoplankton species, as well observed in sea bass, rabbitfish and (Sapian strain) at SEAFDEC/AQD was as earlier introduction of Artemia milkfish larvae. Larvae of these three necessary. Using screened Brachionus, nauplii. Larvae survival rates attained in species had prey sizes which were survival of red snapper improved at day 3 t tanks in this study with Brachionus about 20-80% of their mouth width. For 14, similar to the results of other only for 21 days were comparable with anchovy larvae, it had a 76% prey width researchers. However, Doi and his those obtained by other researchers to mouth width ratio and observed that companions in 1991 found no beneficial who used copepod andBrachionus the prey were eaten “end first.” Duray effect of screened Brachionus for together. Phytoplankton in rearing and Kohno in 1990 believed that the grouper larvae but obtained good tanks improved growth and survival of size threshold of prey ingested by the survival with SS-Brachionus. Growth of

4 SEAFDEC Asian Aquaculture Vol. XIX No.March 1 1997 the larvae was not enhanced using supplied consistently and at the screened Brachionus until day 14. appropriate density for mass fry NETWORKING Although a higher rate of Brachionus production, it is still being used in feeding was observed as larvae grew, it hatcheries. The nutritive value of AQD in a consortium for could not quantitatively sustain growth. Artemia may be enhanced by feeding community-based Sequencing of small and then bigger them a high HUFA diet prior to feeding resource management Brachionus during the first two weeks of them to the larvae. Otherwise the live rearing should be done since this food has to be supplemented by an Making sure of sustainability feeding regime has been found to be artificial diet. Although HUFA-enriched The much needed shot-in-the-arm effective in rearing gilthead seabream instar II Artemiawere given for six days, for the development of rural based larvae. On the other hand, Duray the duration of the enriched Artemia community resource management (unpublished) obtained better growth feeding should be determined for has been strengthened with the and survival of red snapper larvae fed effective utilization. On-grown Artemia, signing of a Memorandum of Under­ Brachionus supplemented with artificial known to contain a high level of protein, standing among leading institutions diets than those fed only Brachionus may also need to be enriched with high concerned with marine resources during the first 14 days of culture. HUFA to meet the larval requirement for management. AQD Chief Rolando R. n-3 fatty acids. Platon signed on 8 January 1997 a Artemia feeding Memorandum of Understanding Like Brachionus, Artemia is Feeding frequency between SEAFDEC, the Interna­ important in rearing marine fish larvae. Feeding larvae with Artemia at 2/ml tional Center for Living Aquatic Earlier workers used Artemia nauplii once a day produced longer and Resources Management (ICLARM), starting on day 10 or 15. In the present heavier larvae but, in terms of survival, the SEAMEO Regional Center for study, very few day 15 larvae ingested four times a day produced the best Graduate study and Research in Artemia nauplii. To improve utilization result. Frequent feeding led to more Agriculture (SEARCA), and the and save costs, feeding with Artemia efficient utilization of feed, better feed Tambuyong Development Center started when larvae were >6.0 mm, conversion, and reduced variation in (TDC), a local NGO concerned with around day 21. Perhaps the other water quality. However, because of the protection of marine resources workers used a brand of Artemia that higher larvae density in the tank at four and welfare of local communities. produced smaller nauplii than that used times a day feeding, larval growth was The agreement will assist in the in this study, or their larvae were larger affected. Snapper larvae may be fed a improvement of coastal resources on day 15, such that earlier feeding with higher daily ration of Artemia (2-3/ml) if and quality of life of coastal resi­ Artemia was feasible. Artemia is the ration is given in smaller amounts dents. AQD will spearhead the believed to contain certain several times a day. dissemination and transfer of appro­ metamorphosis-enhancing substances. Experimental results showed that priate aquaculture technologies to Metamorphosis is a sensitive, difficult snapper larvae survived better in bigger Palawan-based institutions. The first stage of larvae development. If (3 t conico-circular concrete) tanks. activity is an aquisilviculture activity metamorphosis can be accelerated Survival improved with the use of small to demonstrate crab fattening in through manipulation of the nutrient Brachionus during the first two weeks of mangrove swamps while preserving value of the larval food, likeArtemia, culture. Increasing the Artemia feeding the . survival might be improved and the level and frequency (2/3 ml at four Other signatories to the agree­ hatchery operation might be shortened. times a day) promises to improve ment were: Dr. Meryl Williams, Growth of snapper larvae increased growth and survival to harvest. Director-general of ICLARM, Dr. with the Artemia feeding level. Survival Enriching on-grown Artemia with high Percy Sajise, Director of SEARCA, was inversely related to the feeding HUFA feed before feeding them to and Prof. Carlito Añonuevo, Execu­ level, suggesting that Artemia is not snapper larvae should be done in the tive Director of TDC. very suitable for red snapper larvae, or future. It is envisioned that if the pilot that high Artemia density adversely project is successful in Palawan, a affects water quality as has been similar co-management scheme will reported in other fish larvae. But since be done in Viet Nam. at present, Artemia nauplii can be SEAFDEC Asian Aquaculture Vol. XIX No.March 1 1997 5