Effect of bait species and color on sea turtle bycatch and fish catch in a pelagic longline fishery

Published source details Yokota K., Kiyota M. & Okamura H. (2009) Effect of bait species and color on sea turtle bycatch and fish catch in a pelagic longline fishery. Fisheries Research, 97, 53-58.
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This study is summarised as evidence for the following.

	Action	Category
	Use dyed bait Action Link
	Use a different bait type: Sea turtles Action Link

Use dyed bait

A paired study in 2002–2003 in pelagic waters in the North Pacific Ocean (Yokota et al. 2009) found that using blue–dyed fishing bait did not reduce unwanted catch of loggerhead turtles Caretta caretta in a longline fishery, regardless of bait species used. There was no difference in the rates of unwanted catch of loggerhead turtles between blue-dyed and non-dyed bait (9 individuals caught in each case). All turtles were caught alive and subsequently released. Bait colour did not alter the catch rates of commercially-targeted swordfish Xiphias gladius. Longlines were deployed from a single vessel (54 m long) in May–June 2002 and 2003 (19 deployments/year). Whole mackerel Scomber japonicus and squid Todarodes pacificus were used as bait. Half of the bait of both species was dyed blue using non-toxic dye and the two bait species (dyed and non-dyed) were attached alternately to standard Japanese hooks (size 3.8-sun, 10° offset; 960 total hooks). Hooks were set to a depth of 40–90 m and lines were deployed overnight.

(Summarised by: Katie Sainsbury)
Use a different bait type: Sea turtles

A paired study in 2002–2003 in pelagic waters in the North Pacific Ocean (Yokota et al. 2009) found that using fish instead of squid as bait reduced unwanted catch of loggerhead turtles Caretta caretta in a shallow-set longline fishery. Catch of loggerhead turtles was reduced using mackerel Scomber japonicus bait (4 individuals) compared to using Japanese common squid Todarodes pacificus (18 individuals). All turtles were caught alive and subsequently released. Bait type did not alter the catch rates of commercially-targeted swordfish Xiphias gladius, bigeye tuna Thunnus obesus, blue shark Prionace glauca, and shortfin mako shark Isurus oxrinchus (see original paper for details), but increased catch of striped marlin Tetrapturus audax (mackerel: 14 individuals; squid: 5 individuals). Longlines were deployed from a single vessel (54 m long) in May-June 2002 and 2003 (19 deployments/year). Whole mackerel and squid were used as bait. The two bait species were attached alternately to standard Japanese hooks (size: 3.8-sun, 10° offset, 960 total hooks). Hooks were set to a depth of 40–90 m and lines were deployed overnight.

(Summarised by: Katie Sainsbury)