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Reproductive Cycle of the Razor Clam Solen marginatus (Pulteney, 1799) in the Southern Mediterranean Sea (Gulf of Gabes, South Tunisia)

Ayache, Nadia, Hmida, Leila, Cardoso, Joana F. M. F., Haouas, Zohra, Costa, Fiz Da, Romdhane, Mohamed S.
Journal of shellfish research 2016 v.35 no.2 pp. 289-397
Veneroida, autumn, body condition, chlorophyll, clams, cold season, gametogenesis, harvesting, spawning, summer, temperature, winter, Mediterranean Sea, Mediterranean region, Tunisia
Razor clam species are commercially important worldwide. In Tunisia, studies on razor clams aim to promote harvesting and ensure a rational and durable exploitation. In Tunisia, Solen marginatus (Pulteney, 1799) is the most abundant razor clam species although Ensis species, particularly Ensis minor, are also found. The aim of this study is to understand the allocation strategies of S. marginatus in terms of growth and reproduction. For that, condition indices and histological analysis were performed and related to temperature and chlorophyll a. Clams were collected monthly in the southern Mediterranean Sea (Gulf of Gabes, Tunisia). Body and somatic mass increased in summer and autumn. Body condition was highest in September 2007 and the highest somatic condition index was measured in August 2008. Body and somatic mass loss occurred in winter and late spring-early summer with lowest values found, respectively, in February and May 2008. Gametogenesis rate was slow and held in a synchronous way during the cold season, leading to massive spawning and exhaustion in July 2008, and probably in June 2007. The abundant food conditions and elevated temperatures during the summer initiated a new gametogenic cycle and partial spawning events were observed in autumn 2007, after which high restoration activity occurred. The species seems to have adopted two reproductive strategies: a conservative strategy during the cold season, when food is scarce, and an opportunistic strategy during summer and autumn, when food is abundant and temperatures are high.