The proposal has been put into practice in a practical guide developed as part of the DELASMOP project, a partnership between Centro de Ciências do Mar do Algarve (CCMAR) and the Interdisciplinary Centre for Marine and Environmental Research (CIIMAR) and proposes practical measures to reduce the by-catch of sharks and rays that are victims of trawling for crustaceans in the Algarve.
Crustacean trawling, although important for some coastal communities, has a considerable environmental impact and has discard rates of 70 per cent, affecting species of no commercial interest or under legal protection. These include rays and sharks, which are often caught as bycatch during this type of fishing. The data collected by the project’s team of researchers reveals that 95 per cent of the rays and sharks caught as bycatch in trawls arrive on board dead or dying. To compound the problem, the pressure on coastal resources is pushing fleets into deeper waters where little-known species of great ecological importance live.
The ‘Guide to handling sharks and rays for trawlers’ was developed as part of the DELASMOP project, the result of Sofia Graça Aranha‘s doctoral thesis at CIIMAR and CCMAR with co-supervision of the researcher Ester Dias from CIIMAR, and whose research has been centered on the study of deep-sea elasmobranchs: sharks and rays that inhabit the most unexplored marine ecosystems off the Algarve coast.
Shark and ray species affected
In March 2021, during a field expedition as part of the DELASMOP project, 15 different species of deep-sea elasmobranchs were identified, including rarities such as the goblin shark (Mitsukurina owstoni), the enigmatic snake shark (Chlamydoselachus anguineus) and the peculiar sail hogfish (Oxynotus paradoxus). Bycatch has therefore become one of the main threats to the conservation of these animals. In this context, the practical guide now being developed is a response to current and emerging threats.
Recommendations for more sustainable fishing
Despite the European Union’s ban on bottom trawling below 800 metres, the activity persisted during the years under study (2018-2022).
The ‘Shark and ray handling guide for trawlers’ is a valuable tool for supporting the fulfillment of Portugal’s international commitments in terms of marine conservation, as well as contributing to the objectives of the European Green Deal and the EU Biodiversity Strategy for 2030.
Among the measures proposed are strategies such as selecting fishing depths with a lower abundance of elasmobranchs, using meshes of different sizes and shapes, and reducing trawling time. It also recommends raising awareness and providing training amongst crews to enable the correct handling and identification of the species caught.
Download the Guide to handling sharks and rays for trawlers here.
See the full press release here.
Photo by Sofia Graça Aranha.
