This study is conducted to develop a sampling program and to determine the optimum stocking density for Artemia production in earthen ponds.

The use of yeast as feed in aquaculture is discussed. It has been successfully used as feed for Penaeus japonicus larvae, for Brachionus plicatilis mass culture, and for the improvement of nutritional quality of Tigriopus japonicus. It has been found most effective as supplemental food when enough phytoplankton cannot be supplied.

Natural populations of oysters and mussels have long been gathered for food by coastal communities in the Philippines, and bivalve farming began in early 1900. The first farms were no more than a series of bamboo poles inserted in the muddy bottom of Manila Bay in Bacoor Cavite. In May 1934, the Bureau of Fisheries and Aquatic Resources (BFAR) established a pilot oyster farm in Binakayan, Cavite Province, Luzon, and a lucrative industry soon grew up. By 1950, about 200 ha of private farms existed in Bacoor Bay, but, in the late 1950s, mussels appeared on the farms and threatened the industry. The response of BFAR was to initiate farms for mussels, and the results prompted the establishment of a mussel industry that proved to be at least as lucrative as the oyster industry. Farming of windowpane oysters (Placuna placenta) began in the late 1940s in the tide flats of Bacoor Bay, the delicate, translucent Placuna shells being used for window glazing and shellcraft. In the early 1970s, however, the bay became increasingly polluted, the stocks could not survive, and they are still not found in the waters of the bay.

The freshwater prawn Macrobrachium abounds in the rivers, lakes and estuaries of the Philippines. At SEAFDEC, Binangonan Research Station, a few preliminary studies have been conducted on Macrobrachium sp. and M. rosenbergii . A recent preliminary survey of nearby river systems showed that there is a big demand for Macrobrachium in the market.

For hatchery production of Penaeus monodon and other penaeid fry, the SEAFDEC Aquaculture Department is dependent mainly on captive broodstock in the form of ablated females, using up to 1,500 spawners in one year. The availability of such broodstock has enabled us to gather information on the reproductive biology as well as broodstock techniques for P. monodon and other species. This paper discusses studies on courtship and mating behaviour, fecundity, egg quality and rematuration; and requirements for induced maturation (source and age of stock, sex ratio, feeding, tank management, etc.) of P. monodon. A comparison of biological and construction requirements of two broodstock systems — land-based tanks and marine pens — is made. Work on other penaeids, mainly P. indicus is discussed. Lastly, areas for future research on penaeid maturation are highlighted.

A review is presented of some practical methods that may be applied by fish farmers in producing food organisms for fish and prawn hatcheries. Organisms involved in the discussion include Moina, chironomid larvae, mosquito (Culex) larvae and earthworm (Lunbricus).

Successful molts and morphological defects in P. monodon zoeae (Z₁, Z₂, Z₃) resulting from a 24-h exposure to 1.0 and 2.0 mg/L furanace in baths of 1.0 and 2.0 mg/L were quantified. Molting was delayed in Z₁, but not in Z₂ and Z₃ at 1.0 mg/L; considerably delayed in all sub-stages at 2.0 mg/L. Morphological defects in the telson, carapace, uropods and pereiopods were observed in high frequency in Z₃ after the exposure. These abnormalities did not result in 1.0 mg/L. In Z₂, a 6-h exposure is deemed optimum for bath in 1.0 mg/L as gauged from higher survival of larvae after 96 h.