Reproductive cycle of the traditionally exploited sea cucumber Holothuria tubulosa (Holothuroidea: Aspidochirotida) in Pagasitikos Gulf, western Aegean Sea, Greece

Abstract

The reproductive cycle of the traditionally exploited sea cucumber Holothuria tubulosa was investigated in the Pagasitikos Gulf (39 degrees 18'457 '' N, 23 degrees 05'869 '' E) from June 2007 to July 2008. The study examined the microscopic characteristics of the gonads and was based on maturity index (MI) and oocytes' size-frequency distribution. The reproductive cycle was found to be synchronous between sexes, following an annual pattern. The minimum MI values were recorded in December and January, marking the onset of the reproductive cycle. During the spring, MI increased due to gamete development and proliferation. Mature specimens were prominent in summer while spawning occurred between July and September. The maximum MI values were recorded in mid-autumn, when most specimens were at the postspawning stage. The oocytes' size-frequency distribution showed analogous seasonal variability. The present findings are crucial for establishing an efficient management strategy for this commercial and ecosystem-engineering species, since its exploitation in Greek waters has not been under official control for more than a century. The authors propose a seasonal ban on the exploitation of the species from July to September and a minimum individual drained weight limit of 250 g.