Working together with fishermen is essential for finding suitable solutions to reduce seabird bycatch. Their specialist knowledge about how their gear works and how to effectively catch their target species is helping us to design the most appropriate bycatch reduction methods without affecting their valuable catches. Hence, the main purpose of our demersal longline work for the next months is to encourage fishermen to cooperate and to enlist their direct involvement in finding solutions.
Our first challenge is testing the feasibility of a fishing gear configuration that is commonly used by artisanal fishers in Chile to target Austral hake (Merluccius australis). It has been demonstrated that this fishing gear has less impact on seabirds, as its rapid sink rate limits the seabird’s access to baited hooks. This is a key feature to reduce the catches of the diving species which can reach a depth of several meters, such as the shearwaters. Through the support of the ACAP Secondment Programme, I was in Chile for two months with the aim of understanding “in situ” how the Chilean gear works, its main components and characteristics. The experience I gained is now being used to tackle bycatch mitigation in the local demersal longline fishery in Catalonia- essentially adapting the Chilean gear to Spanish boats.
The gear is composed of a number of vertical lines o “espineles” distributed along a horizontal line (Figure 1). Each vertical line contains several hooks located at different depths and, at the end, there is a large weight that pulls the hooks down very quickly, reducing the time that bait is available to seabirds and therefore their risk of being bycaught.
Antonio, a longline fisherman from Llançà (Northern Catalonia), is working with our team on the process of adapting the Chilean gear to the local boats. His long experience and contribution are crucial to building the gear correctly, to finding the most effective variations and to assessing its feasibility.
In these last weeks, we have gone to sea with Antonio to make the first tests with the new gear. These initial trips served to learn how the gear works and to reveal possible problems or what we should improve. We also collected data on how fast the baited hooks are sinking, and our preliminary outcomes showed that they sink at around 0.8 m/s in first 10m depth, this being far greater than the sink rate recommended to avoid seabird catches (0.3 m/s). Regarding the commercial fish catches, unfortunately we haven’t caught any individuals of the target species yet, although at this moment the number of settings achieved is still insufficient to make a proper assessment of these results. We will post again soon to let you know how our trials get on!
Moreno, C. A., Arata, J. A., Rubilar, P., Hucke-Gaete, R., & Robertson, G. (2006). Artisanal longline fisheries in Southern Chile: Lessons to be learned to avoid incidental seabird mortality. Biological Conservation, 127(1), 27–36.