|Date||31 Mar 2020|
East Flores in the Savu Sea provides migratory corridor, foraging ground and nursing ground for 22 species of marine mammals (MMPATF, 2019a), and home for thousands of Mobulid ray (Lewis et al., 2015). However, Lamakera villagers in East Flores is infamous as the world’s largest manta ﬁshery, where hundreds of Manta and Mobula rays were landed annually in this small Indonesian village to supply the global demand for Mobulid products.
Since the conservation intervention in 2014 by local government which collaborated with NGOs, targeted manta ﬁshery has decreased by targeted 97 % (Misool Foundation, 2019). However, despite the almost 100% reduction in targeted Manta hunting in Lamakera, this work in the region has highlighted another signiﬁcant threat (bycatch from gillnet ﬁshery) that might impact Manta and Mobula populations in the East Flores region. Based on Misool Foundation data, the numbers of Mobulids (Mobula mobular) catch from gillnet ﬁshery has increased up to 6 times higher than before. Furthermore, survival of bycaught elasmobranchs is species-speciﬁc and is inﬂuenced by size, respiratory mode, ﬁshing gear type, capture duration, behaviour during capture (i.e. ﬁght), air exposure duration (see Bagarran-Mendez et al., 2019).
We aim to identify what variables aﬀect Manta ray survival in gillnets at a manta ray bycatch hotspot in East Flores, as a basis for reducing mortality through better management measures in Indonesia, but with potential conservation beneﬁts for other high-risk countries, such as Peru, Sri Lanka, and the Philippines (Lawson et al., 2017). This information is highly relevant to identify speciﬁc measures to be implemented in ﬁsheries management, such as soak durations and handling guidelines.
In order to quantify post-release mortality, satellite tags (n=20) will be opportunistically tagged to Oceanic manta rays as bycatch in gillnet fisheries during normal fishing operations. These tags are designed for short-term survivorship studies and will be popped-up to the surface after the death of the animal or once the animal has survived for the maximum deployment timespan of 60 days. Socio-eonomic surveys will be conducted with different levels of the supply chain which will provide insight into trends in fisheries and socio-economic value. Habitat use will be analysed using summary data from satellite tags to predict overlap with fisheries and or identify bycatch hotspots.
Our project will contribute to new policy frameworks ultimately setting in place management measures that will result in a reduction of manta ray fisheries mortality in non-selective gear.
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