Health management in tropical aquaculture systems
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Health management strategies are very important in aquaculture. In Asia, health management practices are broadly similar for the various aquatic species that are cultured. These focus mainly on maintaining the good health of the organisms throughout the life cycle. Good health management is based on an understanding of the interactions between the environment (water), the host, and the pathogens. In an ideal system, the three factors are balanced to offset a disease process. This balance is difficult to maintain in an intensive culture system and significant mortalities usually result. The outbreak of disease is thus related to poor health management. This paper deals with the health management practices applicable to the hatchery and grow-out stages of shrimp and fishes cultured in the tropics.
Shariff, M. (1995). Health management in tropical aquaculture systems. In T. U. Bagarinao & E. E. C. Flores (Eds.), Towards Sustainable Aquaculture in Southeast Asia and Japan: Proceedings of the Seminar-Workshop on Aquaculture Development in Southeast Asia, Iloilo City, Philippines, 26-28 July, 1994 (pp. 73-80). Tigbauan, Iloilo, Philippines: Aquaculture Department, Southeast Asian Fisheries Development Center. http://hdl.handle.net/10862/126
PublisherAquaculture Department, Southeast Asian Fisheries Development Center
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Evaluation of density and cage design for the nursery and grow-out of the tropical abalone Haliotis asinina Linne 1758 VC Encena II, M de la Peña & VT Balinas -
Journal of Shellfish Research, 2013 - National Shellfisheries AssociationThe effect of stocking density and cage design on the growth, survival rate, and feed conversion ratio was evaluated for the nursery (11–15 mm in shell length) and juvenile grow-out (26–30 mm in shell length) of the tropical abalone Haliotis asinina. Abalone were fed Gracilaria sp. within a randomized 2 × 3 factorial experiment using 2 stocking densities (Tl (500 pieces/m2) and T2 (1,000 pieces/m2)) and 3 cages (D1, box; D2, mesh cage; D3, prefabricated multitier trays). In addition, 3 stocking densities (T1, 50 pieces/m ; T2, 100 pieces/m; T3, 200 pieces/m) were evaluated in the prefabricated multitier trays. We found that, in the nursery experiment, 4-mo-old tropical abalone juveniles reared for 90 d showed no significant differences in growth (shell length and body weight) and survival rates among the 3 nursery cages used (Tukey's post hoc test, P > 0.05). Feed conversion ratio, however, was lowest for the high-density treatment T1D3 (7.8 ± 0.76) and was significantly different from the low density treatment T1D1 (11.32 ± 1.2) and intermediate density treatment T1D2 (12.39 ± 1.12; t-test, P > 0.05). Conversely, at higher densities (T2), the same trend applied with abalone reared in multitier basket systems (T2D3), having the highest growth rates and survival rates (29.3 ± 0.07 mm average shell length (ASL) and 5.16 ± 0.52 g average body weight (ABW)), followed closely by those reared in mesh cages (T2D2) and boxes (T2D1). Feed conversion ratio was also lowest for T2D3 (7.56 ± 0.79) and was significantly lower than T2D1 and T2D2. Between treatments, however, abalone reared at lower densities (T1) had significantly higher growth and survival than those reared at higher densities (T2), regardless of the nursery cage used, indicating an inverse relationship between stocking density, growth, and survival. For the grow-out study, tropical abalone reared in multitier trays at low densities (T1) attained the highest growth in shell length and body weight (49.7 ± 0.11 mm ASL and 29.8 ± 2.6 g ABW, respectively) at 180 d of culture, which was significantly greater than those reared in the high-density treatment (T3) with significantly smaller shell length and body weight (43.8 ± 0.18 mm ASL and 21.2 ± 2.0 g ABW), but not significantly different than the intermediate density treatment. This trend started from day 60 of culture onward when analyzed using Duncan's multiple range test (P > 0.05). Survival rates were not significantly different among stocking density treatments, nor were feed conversion ratios. We recommend, for nursery rearing of abalone juveniles, using multitier trays (D3) or boxes (D1) at 500 pieces/m2 stocking density to attain a grow-out size of 26–30 mm in shell length in 90 days. A stocking density of 100 pieces/m2 is recommended to grow abalone in multitier trays to attain a cocktail size of 50 mm ASL and 30 g ABW in 180 d with survival rates between 85.6% and 83.1%.
Book chapterJH Primavera - In SS De Silva (Ed.), Tropical Mariculture, 1998 - Academic PressIn December 1996, the Supreme Court of India ordered the closure of all semi-intensive and intensive shrimp farms within 500 m of the high tide line, banned shrimp farms from all public lands, and required farms that closed down to compensate their workers with 6 years of wages in a move to protect the environment and prevent the dislocation of local people. If the 1988 collapse of farms across Taiwan provided evidence of the environmental unsustainability of modern shrimp aquaculture, the landmark decision of India's highest court focused attention on its socioeconomic costs. This chapter briefly describes shrimp farming, discusses its ecological and socioeconomic impacts and recommends measures to achieve long-term sustainability including improved farm management, integrated coastal zone management, mangrove conservation and rehabiUtation, and regulatory mechanisms and policy instruments.