The study regarding the annual pattern of Pinna nobilis settlement in Karantina Island (Izmir Bay, Turkey) was conducted using artificial polyethylene-mesh bag collectors (onion bag). The samples were collected by a SCUBA diver at intervals of 4 weeks, also replacing the collectors during 12 months at 8-m depth. In addition, environmental parameters, such as temperature, salinity, chlorophyll-a, particulate organic matter and particulate inorganic matter in water column, were monthly measured. Fifteen bivalve species were recorded, and among these, Ostrea edulis, Pinctada radiata, Chlamys varia, Chlamys glabra, Modiolus barbatus, Mytilus galloprovincialis, Arca noae, and Anadara inaequivalvis have a commercial value. P. nobilis represented 0.84% of total amount. Settlement was observed only in August (122 individuals/0.4 m(2)) and spat data showed significant variations between outside (8%) and inside (92%)of each mesh bag collector but also the deployed time (P<0.05). Length of spat ranged between 0.3 and 15.3 mm. These results showed that reproduction period of fan mussel was during summer months in Izmir Bay, and fan mussel was collected especially in August from natural area.