Bycatch, discards and survival rates in the small-scale cuttlefish trap fishery on sandy bottoms off the Algarve coast (southern Portugal)

This study reports a detailed description of the bycatch, discards and survival rates in the cuttlefish (Sepia officinalis) trap fishery off the Algarve coast (southern Portugal). A total of 86 fishing surveys involving 6,311 cuttlefish traps were performed between May and September from 2009 to 2014. Bycatch species were caught in 1,037 traps (bycatch catchability rate of 16.4%), comprising 1576 individuals with an overall weight of 268.3 kg. During the study period, bycatch CPUEs were 12.5 ind./50 traps and 2.1 kg/50 traps, with bycatch rates of 21.1% by number and 15.9% by weight. Thirty-four species (89.5% of bycatch taxa) were discarded at sea, corresponding to discard rates of 19.5% by number and 11.1% by weight. The short-snouted seahorse, Hippocampus hippocampus (L.), was the third most abundant bycatch species (11.6% No.; 0.4% kg) and the second most discarded (12.6% No.; 0.6% kg), being invariably discarded live and undamaged owing its conservation status. This markedly seasonal small-scale trap fishery constitutes a locally important socio-economic activity during spring and summer, characterised by low bycatch and discard rates, complemented by high survival rates of discards.