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• Potentials of Kappaphycus striatum (Schnitz) and Gracilaria heteroclada Zhang (Ad Xia) to control the growth of luminous bacteria Vibrio harveyi 

  EA Tendencia & MR de la Peña - The Philippine Agricultural Scientist, 2010 - University of the Philippines Los Baños

  Different aquaculture species such as finfishes and bivalves have been reported to control the luminous bacterial disease of shrimp, usually caused by Vibrio harveyi. The use of seaweeds in shrimp culture system has reportedly improved water quality and reduced the bacterial count. This study evaluated the potentials of two species of seaweeds, Gracilaria heteroclada (Ad Xia) and Kappaphycus striatum (Schnitz), to control the growth of V. harveyi.

  V. harveyi was inoculated into control tanks containing shrimps only and into treated tanks containing both shrimp and macroalgae. Luminous bacterial counts were monitored daily. From day 2 to day 6, luminous bacterial count in tanks with G. heteroclada was significantly lower than those in tanks with K. striatum. Bacteria isolated from the rearing water containing K. striatum and G. heteroclada and from the seaweed homogenized in sterile seawater showed anti-Vibrio harveyi activity. The seaweed homogenate per se also showed anti-luminous bacterial property. Presence of both G. heteroclada and K. striatum in shrimp culture system has the potential to control the growth of luminous bacteria. G. heteroclada was more efficient and sustainable, as shown by the lower luminous bacterial count and the higher percentage recovery of this macroalga after 11 d in experimental tanks.
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  Conference paper

  Aquaculture development in Japan 

  S Mito - In JV Juario & LV Benitez (Eds.), Seminar on Aquaculture Development in Southeast Asia, 8-12 September 1987, Iloilo City, Philippines, 1988 - Aquaculture Department, Southeast Asian Fisheries Development Center

  Along with the growth of the national economy, aquaculture in Japan has steadily developed in recent years. From 1976 to 1985, production of cultured fish and shellfish increased by 28% from 927 thousand mt to 1184 thousand mt. The contribution of aquaculture to total domestic production constituted 22% in value and 9.7% in weight for 1985. Increase in aquaculture production may be attributed to stronger domestic consumer demand for high grade fish products.

  The principal species for culture include sea bream (Pagrus major), black sea bream (Acanthopagrus schelegi), yellowtail (Seriola guinqueradiata), Japanese flounder (Paralichthys olivaceus), pufferfish (Takifugu rubrives), Kuruma ebi (Penaeus japonicus), abalone (Nordicus discus), blood ark shell (Scapharca broughtonii) and edible seaweeds (Porphyra, Undaria, Laminaria). Rapid strides in improved culture techniques have been attained in seed production, grow-out, harvest and disease control in these various species.

  Present trend show increasing reliance on cultured rather than fishery products to meet market demand. In some species, e.g., coho salmon, rainbow trout, oyster and laver, production depends entirely on culture. In other species, production by aquaculture contribute a significant portion to total production. However, to maintain the balance between supply and demand for certain principal aquaculture products, controlled production is now being practised for certain species. In addition to these trends, technical improvements in aquaculture has led to a decrease in the number of management units and area of facilities devoted to production.

  In the future, greater efforts will be directed to diversify the species cultured to suit consumer preference. Emphasis will also be placed on improving taste and texture of cultured products. New types of feed that will not pollute areas around the culture facilities will be developed. Remarkable achievements in biotechnology will also be applied in aquaculture to improve seed quality.

  Parallel with developments in aquaculture, Japan is exerting greater efforts to propagate fishery resources in coastal waters through stock enhancement activities. This is aimed at establishing a multiple fish and shellfish propagation system in the seas surrounding Japan to maintain or increase production from fishery resources.
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  Conference paper

  Recent developments in aquaculture in Japan 

  K Fukusho - In TU Bagarinao & EEC 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, 1995 - Aquaculture Department, Southeast Asian Fisheries Development Center

  Aquaculture production in Japan in 1993 was 1,351,000 tons, 15.6% of the total fisheries production. About 93.6% came from mariculture and 6.4% from freshwater aquaculture. The per cent contribution of aquaculture to total production has increased in recent years but partly because marine fisheries,especially of sardine and pollack, have decreased. Aquaculture has reached a plateau, and decreased slightly between 1992 and 1993. Diverse marine and freshwater species are cultured in Japan — various fishes, crustaceans, mollusks, seaweeds, sea squirt, sea urchin, and others. Research and development in mariculture focus on finding substitutes for animal protein in feeds, improvement of fish quality, protection of the culture environment, use of offshore floating culture systems, and protection from diseases. Research in freshwater aquaculture has expanded to include recreational fishing, the propagation and preservation of endangered species, and the construction of fish ladders for salmonids and other migratory species.