Preliminary investigation on the use of artificial substrates to favor Tritia mutabilis (Linnaeus, 1758) spawning in Central Adriatic Sea: a possible contribution to stock maintenance

Abstract

          Tritia mutabilis, formerly classified as Nassarius mutabilis, represents an important but declining resource for small scale fishery in the central Adriatic Sea, likely due to overfishing. A preliminary investigation on the use of artificial substrates to favour its spawning was carried out in a coastal area off the Abruzzi region, central Italy. Between May and June 2015, five groups of six pyramid structures made of a steel frame covered by plastic net, with a 0.5 m² surface available for deposition, were placed on sandy bottoms at about 0.5 nautical miles from the coast and at sea depths ranging from 5.5 m to 7.5 m. A density of T. mutabilis egg capsules > 1 per 100 cm² was observed in two of the pyramid groups. The number of embryos present in each capsule ranged from 8 to 22 (mean number: 14). At the end of the study, almost all the capsules presented an apical opening and were empty, thus indicating successful hatching and larval release. This preliminary investigation shows that the natural deposition of T. mutabilis egg capsules can be facilitated by placing artificial substrates on sandy bottoms and it is conceivable that their use would contribute to maintain sustainable stocks of this species.