Reproductive cycle of Laevistrombus canarium(Littorinimorpha: Strombidae)in Krabi Province, Andaman Sea, Thailand

ThemesogastropodLaevistrombus canarium,or dog conch, is a commercially valuable species inthe Indo-Pacific region. However, there is no information on its reproductive cycle in Thailand. From December 2012 to January 2014, specimens of dog conch were sampled monthly from Ao Thung beach, on the Andaman Sea, southern Thailand. Seawater pH, temperature and salinity during the sampling period ranged 6.97-8.1, 28-30.8°C, and 27-34 ppt, respectively.Spawning times were investigated through standard gonadal histology andcalculation of the gonad index (GI). The population’s sex ratio departed from 1:1 and females dominated. Five stages of gonad development were found in both sexes: resting, developing,mature, spawning and spent. Monthly variations in these stages and GI showed that this speciesexhibited two major spawning periods: December to April and August to September, and synchronicity existed between the sexes. However, spawning in females wasless frequent and of shorter duration thanin males. The results also revealed that spawning times of S. canariumwere not related to the environmental conditions recorded at the study site. The present study classified this population of L. canariumthatspawn in two clear pulses. The collected data provide baseline information to manage the resources and conservationof L.canariumin the Andaman Sea.