El berberecho Cerastoderma glaucum (Bruguière 1789) es una de las especies de bivalvos más abundantes en los fondos blandos de bahías y lagunas costeras. Esta especie presenta una amplia distribución geográfica, desde los mares Báltico y del Norte hasta el Mar Mediterráneo (Boyden y Russell 1972, Zaouali 1975, Labourg y Lasserre 1980, Brock y Christiansen 1989). Se encuentra a lo largo de las costas del sur de Túnez, las cuales albergan importantes recursos para las pesquerías de Reproductive biology of the cockle Cerastoderma glaucum (Mollusca: Bivalvia) from the north coast of Sfax (Gulf of Gabes, Tunisia) Biología reproductiva del berberecho Cerastoderma glaucum (Mollusca: Bivalvia)
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.
The Mediterranean green crabCarcinus aestuariiwas recorded in Tunisian waters several years ago. However, since its record in the Gulf of Gabes, no studies have been carried out about the spread of this crab. Because there is a lack of nutritional information concerning this species, this study aimed to characterize the chemical composition of hepatopancreas and gonads ofCarcinus aestuariiin view of potential health implication for consumers and to determine the seasonal nutritional quality of females and males taken separately for various size groups. In this study, a total of 1399 individuals were collected along the Sfax coast. The nutritional value of various edible parts ofCarcinus aestuariiwas evaluated, and gender differences in terms of edible yield and proximate composition, protein, mineral, lipid, and water content, were compared for season, age, and sex. The biochemical compositions were strongly influenced by sex, age, and seasons. The highest protein and lipid contents were detected in gonads and hepatopancreas of females. Autumn was the season with the highest protein content and lowest fat content. Therefore, people with particular diets constrains should consume the ovaries of females in autumn and it should moderate in winter. The hepatopancreas and gonads from Tunisian waters can be a good source of proteins and mineral.
The grooved carpet shell Venerupis decussata (=Ruditapes decussatus) (Linnaeus, 1758) is a Mediterranean autochthonous species that in Tunisia is heavily harvested from natural populations. It represents one of the important economic issues, especially in terms of employment and the trade balances of the country via its exportation. Despite its economic value, no studies have been carried out about the spread of this mollusc. Thus the status of this species is still poorly known and there is a knowledge gap about its stocks assessment. This study aimed to investigate the distribution, abundance and population structure of the carpet shell clam in Sfax coastal areas. In terms of geographic occupation, maps of the population distribution were drawn. The results showed a scattered distribution pattern of the species according to location ranging between 0 and 152 ind m−2. The consequence was a remarkable biomass which represented 891 tonnes of total fresh weight and high abundance levels reaching over 261.7 ± 84.2 million individuals estimated in the area of 4182 hectares. The distribution of the species has also been investigated in consideration with the size which varied markedly according to location, the shell length ranged between 2 and 41 mm. The overall sex ratio (F:M) was 1:1.17, which was significantly different from parity (1:1). The size at which 50% of the population reached maturity was 24.08 and 24.76 mm shell length for males and females, respectively. Findings of the current study suggest that V. decussata proliferates along southern Tunisian coasts.
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