Encounters between trawlers and bottlenose dolphins (Tursiops truncatus) occur frequently in the waters of the north of Catalonia, where 86% of bottlenose dolphin sightings are associated with the presence of trawlers. In order to determine the degree and type of interaction between dolphins and fishing in the north of Catalonia, SUBMON carried out the COSTtERA project in 2022 with the collaboration of the Fundación Biodiversidad, of the Ministry for Ecological Transition and Demographic Challenge, through the Pleamar Programme, co-financed by the FEMP. This project aimed to study the behaviour of bottlenose dolphins (Tursiops truncatus) during their interaction with the fishing nets of trawlers. In this study, for the first time in the Mediterranean Sea, underwater cameras were installed on bottom trawl nets, establishing a protocol to assess the underwater behaviour of the dolphins and to determine the nature and risk of the interactions. The study provided valuable images of the underwater behaviour of bottlenose dolphins feeding and interacting with the nets, providing insight into the nature and risk of these interactions.
Following the successful results of the first project, SUBMON starts the COSTtERA-2 project in 2024: Fishing Interaction and Bottlenose Dolphin Behaviour in Trawl Nets in Catalonia, to continue the study. This project is developed with the collaboration of the Fundación Biodiversidad of the Ministry for Ecological Transition and the Demographic Challenge through the Pleamar Programme, and it is co-financed by the European Union through the EMFAF (European Maritime, Fisheries and Aquaculture Fund). In addition, this project contributes to the objectives of the LIFE IP INTEMARES.
This time, the project will apply the methodology developed in 2022, combined with the installation of hydrophones, as well as surveys, maritime surveys and the development of artificial intelligence (AI) algorithms to analyse the data obtained.
The main objective of this project is to visually and acoustically study the behaviour of bottlenose dolphins during their interaction with trawl nets, and to determine the degree and type of interaction between dolphins and fishing in Catalonia through scientific maritime surveys and surveys of both artisanal and trawl fishermen.
Bottlenose dolphin interacting with a trawl net. Photo: SUBMON.
The project is divided into the following study blocks:
- Surveys of artisanal and trawl fishermen in Catalonia to analyse the level of interaction in the area and its impact on dolphins and fishermen. SUBMON has conducted this type of survey in previous years and the results will be used to analyse the trend of these interactions in the area.
- Maritime surveys throughout the year to continue the study of the bottlenose dolphin population in northern Catalonia that SUBMON has been carrying out since 2017, with a particular focus on photo-identification, density and dolphin behaviour.
- Installation of underwater cameras on the trawl nets to study the underwater behaviour of the animals as they interact with the nets.
- Installation of hydrophones on the nets to analyse the sounds of the animals to detect the presence of dolphins and identify acoustic patterns.
- Development of an Artificial Intelligence (AI) algorithm to automatically detect bottlenose dolphin individuals recorded by the hydrophone and cameras. The acoustic algorithm will be used to identify acoustic feeding patterns of bottlenose dolphins.
The COSTtERA-2 project is an ambitious one, and cooperation with the fishing sector is essential to its success. Therefore, local fishermen will be involved in every possible phase of the project.
Thanks to the project, we hope to gain an in-depth understanding of the interaction between bottlenose dolphins and fishing activities in Catalonia by combining standardised (surveys and maritime surveys) and an innovative methodology using underwater cameras, hydrophones and artificial intelligence algorithms.
