Early growth and reproduction of hatchery-produced Pacific oyster Crassostrea gigas in Gamakman Bay off the southern coast of Korea

Abstract

We investigated the early growth and reproduction of hatchery-produced Pacific oysters Crassostrea gigas raised in a suspended long-line facility in Gamakman Bay, off the south coast of Korea. In October 2009, 4 months after transplanting, shell length had increased from 27.4 (July) to 82.5 mm (October), and tissue weight had increased from 0.2 to 5.2 g, indicating that the oyster had reached a marketable size in this month. Histological studies indicated rapid gonad maturation, and the oysters spawned during August and October, with a peak in September. An enzyme-linked immunosorbent assay used to quantify egg biomass revealed that the oysters produced a relatively small quantity of eggs, ranging from 5.1 % (August) to 8.8 % (September) of their body weight. The low total carbohydrate reserve in the tissue recorded in August and September coincided with intense energy utilization due to spawning, while the protein maximum in September matched peak egg mass. Our results suggest that hatchery-produced seed could supply a portion of the spat required in Gamakman Bay as well as in other oyster culture grounds of Korea, where the oyster industry is facing a shortage in the supply of natural spat.