Species and size selectivity in a Portuguese multispecies artisanal long-line fishery

Published source details Erzini K., Gonçalves J.M.S., Bentes L., Lino P.G. & Cruz J. (1996) Species and size selectivity in a Portuguese multispecies artisanal long-line fishery. ICES Journal of Marine Science, 53, 811-819.
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This study is summarised as evidence for the following.

	Action	Category
	Use a different hook type Action Link

Use a different hook type

A replicated study in 1994–1995 in an area of sandy seabed in the Atlantic Ocean, off south-west Portugal (Erzini et al. 1996) reported that using a larger hook did not typically reduce catches of small, unwanted fish, but overall catch rates were reduced compared to smaller hooks. Data were not tested for statistical significance. Overall, the average length of fish caught (34 fish species/groups and one octopus species) was larger for bigger hook sizes (largest hook: 30 cm; intermediate: 29 cm; smallest: 29 cm), but no increase in average size was found for most species, and all hooks caught a wide range of species (see original paper for species individual data). There were small increases however for four of the seven most abundant fish species in catches. Average catch weights were lowest for the largest hook size (largest hook: 77 kg, intermediate: 110 kg, smallest: 107 kg). A total of 45 longlines were deployed from March 1994 to March 1995 in water depths of 13–20 m. Hooks tested were a type commonly used by local small-scale fishers: round bent, flattened sea hooks (Mustad type) in three sizes: 11 (largest), 13 (intermediate, most widely used) and 15 (smallest) (see paper for hook dimensions). Individual longlines with 200–300 hooks of each size (39,900 total hooks) baited with razor clam were deployed for 2–4 h at a time. Catches were separated by hook type and species, weighed and fish total length measured.

(Summarised by: Natasha Taylor)