Grouper research at the Southeast Asian Fisheries Development Center Aquaculture Department
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This paper provides information on grouper research activities that have been carried out in SEAFDEC AQD. It covers various aspects such as broodstock management, seed production, nursery and grow-out culture techniques.
Marte, C. L. (2002). Grouper research at the Southeast Asian Fisheries Development Center Aquaculture Department. In Asia-Pacific Economic Cooperation & Network of Aquaculture Centres in Asia-Pacific (Eds.), Report of the APEC/NACA Cooperative Grouper Aquaculture Workshop, Hat Yai, Thailand 7-9 April 1999 (pp. 143-151). Bangkok, Thailand: Network of Aquaculture Centres in Asia-Pacific.
PublisherNetwork of Aquaculture Centres in Asia-Pacific
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Book chapter | Article
Viral nervous necrosis (VNN) as a critical infectious disease of orange-spotted grouper, Epinephelus coioides, in the Philippines I Kiryu, LD de la Peña, Y Yoshiura, M Ototake & Y Maeno - In K Nakamura (Ed.), Sustainable Production Systems of Aquatic Animals in Brackish Mangrove Areas, 2007 - Japan International Research Center for Agricultural SciencesOrange-spotted grouper, Epinephelus coioides, is a valuable commodity in the Philippines. In 2001, mass mortality occurred in the grouper larvae at Aquaculture Department, Southeast Asian Fisheries Development Center (SEAFDEC/AQD) and the disease was identified as viral nervous necrosis (VNN). Since then, the disease has been observed every year and the grouper hatcheries have been devastated. In this paper, recent studies of VNN which were conducted at the SEAFDEC/AQD from 2001 to 2006 are reviewed. 1) Susceptibility to the VNN virus was tested among fish species that were cultured in mangrove brackish are. Five representative cultured fish species including orange-spotted grouper, Asian sea bass (Lates calcarifer), mangrove red snapper (Lutjanus argentimaculatus), milkfish (Chanos chanos) and rabbitfish (Siganus guttatus) were used in the test where the virus was intraperitoneally injected into the juveniles. Although low or no mortality occurred in the challenge test, histopathological changes were observed in the brain and retina where the virus was re-isolated. The results were the same among the species except for rabbitfish which had no evidence for the infection. It was verified that the virus has a wide host range. 2) To estimate the possible risk of viral spread by vertical transmission, virus distribution was determined in asymptomatic groupers including 7 broodstock and 17 juveniles with body weights ranging from 4 to 12 kg and 2 to 9 respectively. The virus was detected by PCR method. The highest detection rate was in the brain, and the virus was also detectable in other organs such as the gills, heart, spleen, kidney, blood, esophagus, stomach, intestine, liver, gonad, swim bladder and/or skin. 3) As a possible VNN vaccine, a DNA p;asmid encoding the capsid protein of the virus was evaluated. After the challenge, the mortalities between the native and DNA-injected fish appeared significantly different (P<0.05).
Successive spawning of grouper, Epinephelus suillus (Valenciennes), in a tank and a floating net cage Wild Epinephelus suillus (Valenciennes) were collected in 1989 to early 1990. To monitor natural spawning in captivity, 6 mature females (3.5–5.0 kg) and 4 mature males (7–12 kg) were transferred to a 4.6×4.6×2 m concrete tank, and one mature female (5.3 kg) was paired with two spermiating males (6.0–6.5 kg) in a 4×4×3 m floating net cage. Spontaneous spawning occurred successively 5–17 times a month from July 1990 to June 1991 (except in May) in the tank and 5–10 times a month from July to October 1990 in the floating net cage. The number of eggs collected, mean fertilization rate and mean hatching rate in the tank and the floating net cage each month ranged from 0.5–15.8 million and 2.3–3.9 million, 67–88% and 72–89%, and 2–81% and 29–68%, respectively. The onset of the monthly spawning cycle in both holding systems was observed over a period of 3 days either before or after the last quarter moon. The results indicate that a minimum number of E. suillus broodstock are required for a year-round supply of fertilized eggs.
ArticleOptimum packing conditions for the transport of hatchery-reared and wild grouper larvae were investigated under simulated condition or actual air transport. Simulation of transport motion was done through the use of an electric orbit shaker to identify the best packing conditions for the transport of grouper larvae at various ages. Simulated transport was conducted in hatchery-reared grouper larvae at day 35 (mean TL=14.73 mm), 45 (mean TL=15.23 mm) and 60 (mean TL=28.16 mm) at packing densities of 50, 100 and 200 larvae l−1 and at high (28 °C) or low (23 °C) temperatures. Packing density of 50 larvae l−1 was best for 45- and 60-day-old larvae 8 h transport at low temperature. However, packing density could be increased to a maximum of 100 larvae l−1 8 h transport at 23 °C with mortality rates ranging from 2.3% to 5.3%. The increase in total NH3 level was dependent on temperature, packing density and size of larvae. High packing density (100–200 larvae l−1) and temperature (28 °C) resulted in increased NH3 level and mortality rates during transport. In addition, regardless of the temperature, NH3 levels were consistently higher for 60-day-old larvae. Day-60 grouper larvae displayed strong resistance to handling/mechanical stress compared to 35-day-old larvae probably because most are already fully metamorphosed at this stage. Based on these results, a packing density of 50 larvae l−1, a temperature of 23 °C and larval age of 60 days were considered as the best transport conditions for hatchery-reared grouper larvae. When these transport conditions were used in experiment 2, for 26-day-old hormone-metamorphosed, 60-day-old naturally metamorphosed or 60-day-old pre-metamorphosing hatchery-reared grouper larvae, a 100% survival rate was attained in all treatments. Seven days of hormone (T3) treatment did not accelerate metamorphosis of wild-caught transparent grouper larvae (tinies) significantly. Survival rates of hormone-treated transparent tinies (H-tinies), untreated black tinies (B-tinies) and untreated transparent tinies (T-tinies) were also similar after 8–9 h air transport (experiment 3). The results of the current study suggest that T3 treatment did not affect the performance of hatchery-reared and wild-caught transparent tinies/larvae during transport. In addition, mass mortalities of these transported tinies during the nursery phase were associated with nutritional aspect and the sudden confinement of these undomesticated wild-caught grouper to small space rather than transport or hormone treatment effects.