Can shellfish affect the growth of Solen marginatus (Pulteney, 1799)?

Resumen

Various extractive activities take place in the Bay of Cadiz (Southwest of Cadiz). One of them is shellfishing, which is characterized by catching different species of benthic invertebrates including Solen marginatus. This species is highly appreciated gastronomically, indicating their great demand and commercial interest in the area. The objective of this work was to study the growth of this species from samples obtained from the illegal sale by shellfish. The starting hypothesis were: (1) that the average capture sizes for this species are lower than those established by the legislation in force in Andalusia, (2) the each growth ring corresponds approximately with one month of life (moon cycle). The samples were obtained monthly between January and November 2019 (898 specimens). Biometric analyzes were performed and obtained the dry weight (DW) and the ash-free dry weight (AFDW). The counting of marks or rings of growth was made taking a representative sample of each month for each age class and adjusted according to the growth model of Von Bertalanffy. In addition, the observation and monitoring of shellfishers was carried out in the different areas where this activity is carried out. Individuals with sizes less than those established by the current legislation were found (75 mm). The average length obtained was 72.63 mm and this species showed a negative allometric growth. The most frequent rings numbers observed were 15 and 14, which corresponded with 15 and 14 months of age respectively. The results of the Von Bertalanffy growth model were: !" = 106.81, ) = 0.11 y *° = 1.62. In the Bay of Cádiz there is a high stealth activity with S. marginatus, which is negatively affecting its populations. This study will provide a better understanding that will serve to manage their populations in the medium and long term adequately.