Stock mapping, size structure and biological parameters of the clam Polititapes aureus in the shellfish production area of the southern Tunisian waters (Central Mediterranean)

The clam Polititapes aureus is one of the most abundant shellfish species in the southern Tunisian waters. Its current exploitation status and management are becoming a major concern for fishing industry in Tunisia. The significant ecological role of the species and possible future commercial benefits require a better knowledge of its stock. This research is the first attempt to investigate its current status in an area with the largest shellfish production. The obtained results showed a scattered distribution. The stock density ranged from 0 to 124 ind. m⁻², and biomass values varied from 0 to 300 g m⁻². This results in a remarkable biomass of 201.2 (± 64.6) t and high abundance reaching 91.3 ± 32.9 million individuals, estimated an area of 4182 ha. The species distribution was also investigated, with the size ranging from 4.9 to 35.34 mm. The overall sex ratio (F:M) was 1.26:1, which significantly deviated different from parity (1:1). The main environmental factors were identified and several abiotic parameters were found to strongly affect the spread of the clam species. The clam reproduce well and is expected to almost meet the domestic market demand through artisanal fishery.