Hiroshi Ogata - Academia.edu (original) (raw)

Papers by Hiroshi Ogata

Jarq-japan Agricultural Research Quarterly, 2006

Turkish Journal of Fisheries and Aquatic Sciences, Dec 1, 2012

Journal of Aquaculture Research and Development, 2011

Japan International Research Center for Agricultural Sciences eBooks, 2007

Fry of tropical marine fish needed for aquaculture still comes mostly from the wild. Thus, fry av... more Fry of tropical marine fish needed for aquaculture still comes mostly from the wild. Thus, fry availability is a major constraint in the development and extension of aquaculture, especially in rural areas of developing regions. Although the mission of hatcheries is to provide a stable fry production and supply for farmers, fry production remains variable due to poor fecundity and low survival. For the last four years (2002-2005), SEAFDEC/AQD and JIRCAS have conducted the collaborative project that was aimed at developing advanced diets for improving egg production/quality (2002-2005) and larvae/fry quality (2004-2005) through dietary manipulation. Larval rearing tests: In 2005, larval rearing tests (4 trials with rotifers) were conducted to investigate the effects of enriched-live food (4treatments: low (CS) and high (DHAPS) HUFA with or without arachidonic acid supplementation) on survival and growth in rabbitfish Sigunus guttatus fry. Fry fed the rotifers enriched with a combination of DHAPS+5% ArA showed the best survival (44.4±4.5% for D17 fry in the 4th trial).Growth was not different among the treatments (CS, CS+5% ArA, DHAPS, DHPS+5% ArA). Broodstock tests: From March, 2005 to January,2006, a feeding test has been conducted to investigate the effects of dietary ArA supplementation (0% for diet 1, 0.3% for diet 2 and 0.6% for diet 3) on egg production and quality of wild-caught and hatchery-bled rabbitfish broodstock. The broodstock spawned 13 times for diet1 (six pairs), 14 times for diet 2 (five pairs) and 17 times for diet 3 (six pairs) during the period of May 2005 to January, 2006. The total numbers ofhatched-larvae were 3,818 x 103 for diet 1, 4,391 x 103 for diet 2 and 4,597 x 103 for diet 3. The % of normal larvae did not differ among the dietary treatments. Considering together with the results of mangrove red snapper (2003) and rabbitfish (2004), the optimum level of ArA incorporation appears to be between 0.5% and 0.7%. Judging from the results of fatty acid analysis, DHA and arachidonic acid should be supplemented to diets at the same time as to make DHA/arachidonic acid ratio appropriate. Thus, the present study clearly shows that dietary arachidonic acid supplementation is very promising for the development of fry production technologies in tropical areas

Japan International Research Center for Agricultural Sciences eBooks, 2007

Arachidonic acid (ArA) was not a minor component, and ArA distributes widely in coral reef organi... more Arachidonic acid (ArA) was not a minor component, and ArA distributes widely in coral reef organisms. Seagrass had high linoleic acid and linolenic acid levels with low Ara, EPA and DHA levels, while some species of seaweed had intermediate or high ArA levels (5% to 12%). In starfish, sea cucumber and some species of corals, ArA was the first major fatty acid (20% to 30%), but DHA levels were very low. Bivalves, abalone and shrimps had intermediate ArA levels. Total lipids of abdominal muscle and liver of dugong had respectively ArA levels of 7.8% and 11.0%, which were higher than EPA levels (2.4% and 1.6%), but DHA levels (0.4% and 2.3%) were low. It is clear that ArA is a major fatty acid in coral reef animals. The present results suggest that the existence of an ArA-rich food chain may be widespread in coral reef areas, and that the widespread existence of ArA-rich food chain may lead to intermediate or high ArA contents in tropical species

Jarq-japan Agricultural Research Quarterly, 2006

The present study was financially supported by the collaborative project titled “Studies on Susta... more The present study was financially supported by the collaborative project titled “Studies on Sustainable Production Systems of Aquatic Animals in Brackish Mangrove Areas” between Japan International Research Center for Agricultural Sciences, Japan and the Aquaculture Department, SEAFDEC, Philippines.