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The reproductive cycle and potential protandric development of the Noah’ s Ark shell, Arca noae L.: Implications for aquaculture

The reproductive biology of Arca noae (L.) was investigated to assess its aquaculture potential and to achieve sustainable exploitation of this species. A. noae was sampled monthly from Mali Ston Bay, south Adriatic Sea, from November 2001 to October 2002 and from January to December 2004. A total of 590 individuals ranging in shell length from 9.7 to 80.8 mm was analyzed using standard histological techniques. Results indicate that males dominate small shell length categories with females becoming more predominant as size increases. This pattern suggests that some individuals may undergo protandric development. The overall male to female ratio was 1.0 : 1.3 (χ 2 = 9.529, p = 0.002). A number (2.2%) of hermaphroditic animals were also identified. Smallest sexually mature A. noae had a shell lengths of 12 mm. Gametogenic development began in October (female) and November (male), and spawning occurred in summer (July to August). Results of a size frequency analysis of oocyte diameters agreed with a qualitative analysis of gonadal development stages, confirming the occurrence of one annual spawning peak. There was no correlation between mean gonad index and environmental conditions. Data on the reproductive characteristics of A. noae obtained in this study give an insight into the biology of this species and are crucial for initiating its aquaculture.

Arcidae; Arca noae; Adriatic Sea; reproduction; protandry; sex-ratio

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