Catches of Sepia officinalis in the small-scale cuttlefish trap fishery off the Algarve coast (southern Portugal)

摘要

The present study reports a detailed description of the catches of cuttlefish (Sepia officinalis) in the trap fishery performed seasonally off the Algarve coast (southern Portugal). A total of 86 fishing surveys were performed during the fishing season (May-September) from 2009 to 2014, on sandy bottoms at bathymetrics ranging from 8 to 10 m depth. During the whole study period, fishing operations involved 6311 cuttlefish traps with a gear catch rate of 37% (frequency of traps with cuttlefish) and a mean of 0.9 S. officinalis caught per trap. A total of 5883 S. officinalis (1424.0 kg) were caught, being only recorded 282 dead individuals (mortality rate of 4.6%). The mean fishing yield (standardised CPUE's in number and weight) was 46.6 individuals and 11.3 kg 50 traps(-1). Overall, males (n = 3188) outnumbered females (n = 2695), producing a significant male-biased (1 M: 0.85 F) sex ratio. On average, females were significantly larger and heavier (124.4 +/- 22.9 mm ML; 253.1 +/- 148.8 g TW) than males (121.9 +/- 24.0 mm ML; 230.7 +/- 143.1 g TW). Accordingly, the length-frequency distributions displayed significant gender differences, with 89.6% of females and 85.8% of males accomplishing the MCRS (100 mm ML). This markedly seasonal, highly sustainable and low impacting small-scale fishery constitutes a locally important socio-economic activity during spring and summer. Undamaged catches and highly fresh individuals further contribute to the considerable price reached by S. officinalis caught using this artisanal fishing gear.