Suspended cultivation of the Pacific oyster Crassostrea gigas in the Eastern Tropical Pacific

Abstract

The Pacific or Japanese oyster, Crassostrea gigas, was introduced into Ecuador in 1990; however, little is known about its cultivation in the Eastern Tropical Pacific. This study analyzes growth and the influence of environmental factors on two cohorts of C. gigas held in pearl nets suspended from a long line, in Ayangue Bay, Santa Elena Province, Ecuador. Juveniles of 4.8 ± 0.11 mm (cohort I) and 7.3 ± 0.11 mm (cohort II) shell length remained in suspended cultivation for 7 months (beginning August 2014) and 9 months (beginning March 2015), respectively. Intra-monthly, (during the first 2 months), monthly, and bi-monthly sampling of the dorsoventral length, dry biomass of the shell and soft tissues, and the fouling on the shell were determined. Temperature (in a continuous pattern), weekly salinity, and total seston and phytoplankton biomass (chlorophyll a) were determined. Results show that available food, indicated by chlorophyll a, and temperature allowed an adequate development of oysters in culture. Growth in shell size and soft tissues increased with higher temperatures. Crassostrea gigas could reach commercial size in less than 1 year of cultivation. Results of this study demonstrate the biological potential for Japanese oyster culture along the Ecuadorian coast.