A comparison of two blue-dyed bait types for reducing incidental catch of seabirds in the experimental operations of the Japanese southern bluefin tuna longline

The use of blue-dyed bait (both squid and fish) as a means to reduce seabird interactions with pelagic longline fishing gear was tested during Japanese longline fishery survey cruises off South Africa in the Southern Ocean.  The incidental catch of seabirds was lower for both blue-dyed squid and fish baits compared to non-dyed baits. The catch per unit effort (CPUE) of albatrosses decreased when blue-dyed squid and fish baits were used during all years of the study.  The CPUE of petrels was lower during two years when blue-dyed bait was used.  The CPUE of the target southern bluefin tuna was also reduced during all three years when blue-dyed bait was used, except in 2003 when blue-dyed fish bait was used.  A second experiment, testing the use of tori lines and blue-dyed bait (both types) resulted in no interactions with seabirds.