Management of offal discharge

 

This description relies upon Birdlife International Factsheet 12 (2014) and ACAP (2021).

 

Birds are attracted to fishing vessels to feed on processing waste and discarded fish. Removing this source of food can greatly reduce the number of birds associating with fishing vessels. Until recently, most longliners were designed in such a way that offal discharge occurred adjacent to the hauling hatch. This resulted in large numbers of birds feeding amongst hooks that were being hauled aboard. Now, a minimum requirement in many fisheries is to position the scupper, through which waste is discharged, on the port side of the vessel (opposite to the hauling hatch). This helps to divert the birds’ attention away from the area where hooks return to the surface. However, strategic discharge during line setting can increase interactions. Where practical, the discharge of offal should be eliminated or restricted to periods when not setting or hauling, though offal retention and/or incineration may be impractical on small vessels.

 

In summary, ACAP (2021) describe strategic offal discharge as good practice, a supplementary rather than a primary mitigation measure, and recommend that:

• offal and discards should not be discharged during line setting;
• during line hauling, offal and used baits should preferably be retained or discharged on the opposite side of the vessel from that on which the line is hauled; and
• all hooks should be removed and retained on board before discards are discharged from the vessel.

 

Sharks

With regard to sharks, offal management includes the practices of chumming during setting or discarding of offal during hauling. However, little is known of the impact upon shark catch rates of these practices.

A recent (2007, 2008) study of 12 pelagic longline fisheries from eight countries found very few fishers who believed that refraining from chumming during the set and refraining from discarding offal and spent bait during the haul would affect shark interactions. It was found that chumming during setting was not a common practice and that offal and spent bait were typically discarded during hauling operations. Many of those interviewed explained that it would be impractical to retain spent bait and offal to discard at the end of hauling due to limited space on the vessels.