Toshio Saisho

Culture of Tetraselmis tetrathele and its utilization in the hatchery production of different penaeid shrimps in Asia

The prasinophyte Tetraselmis tetrathele is an important live feed organism for shrimp/prawn hatchery operations because of its high nutritional value and ease of culture. It can replace Brachionus plicatilis and Artemia nauplii as live diet during the protozoeal and mysis feeding stage. This study tried to determine the different optimum culture conditions for T. tetrathele, and to evaluate its application in the hatchery production of different penaeid species. Tetraselmis tetrathele was cultured at combinations of six levels of salinities (10–60 g kg−1), nine levels of pH (3–10.5), and two temperatures (25°C and 30°C) in a three factorial combination experiment. Effects of varying concentrations of different organic and inorganic media including the use of vitamins and trace metals were also assessed. The dietary value of T. tetrathele was evaluated by feeding it to different shrimp larvae from protozoea-1 (PZ-1) until postlarva-1 (PL-1).

Developmental Stages of Trachypenaeus Curvirostris (Stimpson, 1860) (Decapoda, Penaeidae) Reared in the Laboratory

[The embryonic and post-embryonic development of Trachypenaeus curvirostris were observed in the laboratory. The eggs hatched as first nauplii after about 15 hours at 25.8°-26.2°C and 32.5 g kg-1 salinity. The larvae were fed only with Chaetoceros gracilis and Tetraselmis tetrathele until early postlarval stage. Six naupliar, three protozoeal, three mysis, and one post-larval stages were described and illustrated in detail. The larval morphological characteristics were compared with those of other species of Trachypenaeus, Metapenaeopsis and Penaeus., The embryonic and post-embryonic development of Trachypenaeus curvirostris were observed in the laboratory. The eggs hatched as first nauplii after about 15 hours at 25.8°-26.2°C and 32.5 g kg-1 salinity. The larvae were fed only with Chaetoceros gracilis and Tetraselmis tetrathele until early postlarval stage. Six naupliar, three protozoeal, three mysis, and one post-larval stages were described and illustrated in detail. The larval morphological characteristics were compared with those of other species of Trachypenaeus, Metapenaeopsis and Penaeus.]

On the Habitat of Nautilus pompilius in Tañon Strait (Philippines) and the Fiji Islands

Since 1981, we have been engaged in field studies of the habitat of Nautilus pompilius in the Philippines (1981 and 1982) and in the Fiji Islands (1982 and 1983) (Hayasaka et al., 1982; Hayasaka, 1983, 1985). The main purpose of these studies was to obtain basic data on the habitat of N. pompilius in the Philippines and in Fiji, which are at opposite ends of the vast distribution range this species. Although the overall project is still in progress, the results of study to date are summarized in this chapter.