Mariculture production in Japan has grown recently to nearly one million tons per year. Mariculture production in the shallow coastal waters of Japan mainly consists of eight species of finfish, six species of shellfish, and three species of algae. Kuruma shrimp culture techniques are highly developed. Nevertheless, only 1,800 tons of kuruma shrimp can be produced yearly. There is a demand for this species but culture grounds have become limited and there is not enough space to raise shrimp. In 1980, 600 million postlarvae were produced but one-half had to be released to the sea. The released shrimp that survived and grew have formed a new basis for the "Sea Ranching Fisheries" industry. The trial releases of postlarvae have proven that sea ranching of shrimp can be successful. To strengthen the foundation of sea ranching fisheries, there must be future research on ecological impact, as well as on physico-chemical water parameters. The life cycle, feeding habits, and predators of the shrimp must also be studied. Recent releases in Hamana-ko Lagoon, Shizuoka Prefecture, made by the research group of the Hamana-ko Substation of the Shizuoka Prefectural Fisheries Research Station have demonstrated the possibilities of sea ranching. This report discusses the research studies obtained at Hamana-ko Lagoon and the main problems of the use of this sea ranching method in mangrove swamp areas of Southeast Asia.

The paper discusses the reasons behind the farming success of Ecuador, as well as the limitations associated with farming throughout the rest of the Americas. Emphasis is given to specific farming practices, management techniques, and physical design characteristics. Through improved techniques the farmer is approaching the point where he can reliably manage his crop size and harvest time as dictated by market trends and postlarval supply. Until recently, pond production has been characterized by relatively small-scale operations often experimental in origin. Due to the farming success in one country, production output has risen from 4,800 tons in 1978 to 23,390 tons in 1983. As evidenced by this dramatic rise in production, Ecuador is in a period of expansion and increasing technical awareness, the combined results of which have led it to become the production leader in pond-grown shrimp. The economic pull towards Ecuador is now slowly giving way to shrimp development in other parts of the Americas. Owing to the technical gains brought about by government programs, universities and private industries, shrimp farming has become a potential activity in many areas previously thought inadequate. Production methods have progressed from the traditional extensive method to sophisticated closed system raceways. All but the latter method are exemplified by the techniques used throughout Ecuador. Presently, Ecuador has in production 50,000 ha of ponds. Of these, 30,000 ha are farmed using the extensive method characterized by low cost and low output. The successful approach referred to as the semi-extensive method occupies approximately 15,000 ha. This style of farming, while requiring increased cost, leads to a proportionately higher production output. The third approach is the semi-intensive method under which an estimated 5,000 ha are in production. Increasingly higher production rates are being achieved through improvements in physical pond design, pond maintenance and preparation, feeding and fertilization regimes, technical management, and control.

A review is made of the current situation regarding Penaeus monodon pond culture in the Philippines, examining in particular pond management practices, including site suitability, engineering design, and harvest and post-harvest handling. Problems and prospects in the industry are also discussed, together with some recommendations.

A review is made of diseases of cultured Penaeus monodon , examining the diagnosis and pathology of the disease or disease agents involved and their prevention and control. Both infectious (viral, bacterial, fungal and protozoan) and other (nutritional, toxic and environmental) diseases are considered.

Following a review of first maturation in Penaeus monodon , details are given of endocrine, nutritional and environmental methods of induced maturation used in aquaculture. Broodstock constitution and maintenance operations are discussed and a comparison made of maturation tanks, pens and cages.

Abstracts of the 6 chapters included in this publication are cited individually.

Two sexually maturing female milkfish were captured in April 1977 and induced to spawn by means of acetone-dried Pacific salmon pituitary powder. The eggs were fertilized and incubated and the resultant young reared to 74-day old, 11 cm long fingerlings. Newly fertilized eggs averaged 1.16 mm in diameter and each had a narrow perivitelline space containing several cortical granules which disappeared within a few minutes. The yolk was slightly yellowish, devoid of oil globules and very finely granulated. Embryonic development was very similar to that of other pelagic fish eggs and hatching occurred between 35 to 36 hr at a salinity of 32 ppt and a temperature range of 28.4-29.2°C.

Milkfish fry catch from Philippine waters can still be increased. Intensified collections in traditional fry grounds and exploitation of new areas may lead to a reduction of adult stock and the possible collapse of the milkfish fry fishery. The implementation of rational conservation and management measures are of immediate concern not only to increase the productivity and number of fry grounds but also to conserve this important aquatic resource. The present methods of catching milkfish fry involve fry filtration by mobile or stationary devices. The design, construction, area and time of operation of the gears are primarily dictated by the bottom topography of the fry grounds, wind direction, local current patterns and tidal fluctuations. Catching, handling, storage and transport activities expose the fish to undue stress which contribute to poor survival. The simple method of lowering the salinity of the water medium considerably reduces mortality. High mortality in nursery ponds has aggravated the seed shortage problem of the milkfish industry. The development of an efficient mass-production technology in rearing milkfish fry to fingerlings and in stunting fingerlings for longer periods could offer the solution not only in meeting the requirements for milkfish seed but also provide part of the fry requirements of other countries in the region.

China is a country with longest history of aquaculture in the world. Comparatively, shrimp culture is a relatively new industry in China. The earliest national production figure of cultured shrimp was 79 metric tons in 1970. It took more than 10 years for the production to reach 10,000 metric tons. The cultured shrimp production reached 10,093 metric tons in 1981. In 1981-1988, China experienced the first golden period of shrimp culture industry development after the full maturation of mass production hatchery technique for shrimp (P. chinensis). The total production of cultured shrimp unbelievably increased to 199,418 metric tons in 1988 from 10,093 metric tons in 1981. However, the good times did not last long. The peak production maintained for 5 years only, ending in 1992 with production of 206,866 metric tons. The serious outbreak of shrimp diseases badly hit China along with other shrimp producers in Asia. This resulted to the drop of cultured shrimp production to 87,856 mt in 1993, 40% of the highest production in 1991 (219,571 mt). The production continued to drop to 63,872 metric tons in 1994. The industry started to recover very slowly in the next 3 years, and regained its production of more than 100,000 tons in 1997 (102,923 mt). The slow recovery in cultured shrimp production in 1995-1998 was mainly due to modification in the culture system and techniques. Since 1998, China has been into a new era of fast growth in cultured shrimp production. The production has been keeping a very fast growth, from 143,086 mt in 1998 to 760,430 mt in 2003. The rapid growth of production during the last several years was mainly due to the rapid expansion of culture of Penaeus vannamei, an exotic shrimp species. Cultured shrimp production in China during 1984-2003. It should be noted that the increase of cultured shrimp production was very abrupt in 2003 in China. It appears unbelievable. Two major reasons could be attributed to it in addition to the expansion of shrimp farming in China in 2003. One is due to the unreported freshwater production of P. vannamei before 2003. It was estimated that production of cultured P. vannamei in freshwater environment reached 160,000 metric tons in China in 2002. This production was not actually included in the total cultured shrimp production of the year. Secondly, it was only in 2003 when brackish and freshwater production of P. vannamei was separately reported.