Aquaculture potential of the Suminoe oyster ( Crassostrea ariakensis Fugita 1913)

Abstract

Oyster production on the West coast of the USA is almost entirely dependent on the culture of the Pacific oyster Crassostrea gigas. Commercial production of the Suminoe oyster Crassostrea ariakensis is presently limited to a few bays in Washington, Oregon and California. The objective of the present study was to determine the aquaculture potential of the Suminoe oyster for the West coast, USA. Female Suminoe oysters became sexually mature about 3 months later than Pacific oysters in Yaquina Bay, OR. Suminoe oyster broodstock could be successfully conditioned at 20 °C for spawning from mid-March until mid-October. Larvae were cultured and successfully set by feeding them on a microalgal diet of the flagellate Pseudoisochrysis paradoxa (VA-12) during the first 7 days of culture and then a diet made up wholly or partly of the diatom species Chaetoceros calcitrans during subsequent weeks of culture. Growth and setting of larvae were greatest at a salinity of 15 to 20 ppt. No successful settlement occurred at 35 ppt salinity. Both Suminoe and Pacific oyster spat grew best at 25 °C and a salinity of 25 to 35 ppt. Growth of Suminoe oyster spat was less sensitive to sub-optimal temperature and salinity conditions than Pacific oysters. In grow-out trials conducted from 1989 to 1993 on the West coast, USA, final shell lengths of Suminoe oysters were significantly less than those of Pacific oysters, but there were no significant differences in tissue dry weights. Both Suminoe and Pacific oysters reached market size for the half-shell trade (60 to 70 mm shell length) 12 to 18 months after planting. Consumer acceptability tests indicated that Suminoe oysters were equal or superior to Pacific oysters in appearance, taste and texture.