This description relies upon:
Birdlife International. 2014. Bycatch Mitigation Fact-sheet 12 (September 2014), Demersal and Pelagic Longline: Haul mitigation.
Birds are attracted to fishing vessels to feed on processing waste and discarded fish. Removing this source of food would 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.
The minimum standard for offal management is the requirement to discharge on the opposite side to the hauling hatch.
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.
Strategic offal management can be inconvenient during operational processes and generally has low compliance. Even with strict regulations and 100% observer coverage to monitor these measures, 100% compliance is not easy to achieve. Greater awareness is needed among fishermen of the long-term implications for birds that are hooked on hauling, as even those released alive face reduced likelihood of long-term survival.
Use of electronic monitoring may be used to assess compliance with the requirement to discharge offal on the opposite side to the hauling hatch.
- ACAP. 2011. AC5 Annex 7 - Summary advice statement for reducing impact of pelagic longline gear on seabirds. Fourth Meeting of the Seabird Working Group, Guayaquil, Ecuador. SBWG-4 Doc 12.
- Birdlife International. 2014. Bycatch Mitigation Fact-sheet 12 (September 2014), Demersal and Pelagic Longline: Haul mitigation.
- Gilman, E., Clarke, S., Brothers, N., Alfaro-Shigueto, J., Mandelman, J., Mangel, J., Petersen, S., Piovano, S., Thomson, N., Dalzell, P., Donoso, M., Goren, M. and Werner, T. 2007. Shark depredation and unwanted bycatch in pelagic longline fisheries: Industry practices and attitudes, and shark avoidance strategies. Western Pacific Regional Fishery Management Council, Honolulu, USA.
- Gilman, E., Clarke, S., Brothers, N., Alfaro-Shigueto, J., Mandelman, J., Mangel, J., Petersen, S., Piovano, S., Thomson, N., Dalzell, P., Donoso, M., Goren, M. and Werner, T. 2008. Shark interactions in pelagic longline fisheries. Marine Policy 32(1): 1-18.