SELETTIVITA’ DEL TRAMAGLIO NELLA PESCA DELLA SEPPIA, SEPIA OFFICINALIS, LINNAEUS 1758, E DELLA TRIGLIA DI SCOGLIO, MULLUS SURMULETUS, LINNAEUS 1758

SELECTIVITY OF TRAMMEL NET TARGETING CUTTLEFISH, SEPIA OFFICINALIS, LINNAEUS 1758, AND STRIPED RED MULLET, MULLUS SURMULETUS, LINNAEUS 1758

Abstract

This study evaluated the selectivity of trammel nets for cuttlefish (Sepia officinalis) and striped red mullet (Mullus surmuletus) in the Tyrrhenian Sea between March 2023 and April 2025. Two nets were tested, differing only in the mesh size of the inner panel (50 mm vs 62 mm). Cuttlefish sizes ranged from 7 to 23 cm, while striped red mullet ranged from 17 to 30 cm. The typical “pocket” catching mechanism of trammel nets proved efficient for cuttlefish, whereas the 62 mm inner mesh appeared too large to retain the commercially valuable sizes of striped red mullet, potentially generating economic losses. Selectivity analyses showed that selection curves for both species followed a Gaussian model (restricted to the left side for cuttlefish), applying correction factors to match observed catch distributions. Overall, the study confirmed the applicability of the simplified Sechin method to trammel nets, although empirical adjustments for mesh deformation and fish body compressibility were necessary.