How do Audouin's gulls interact with fishing vessels? The GAUDIN project informs on the effects of fisheries and the role of RAMPE in the conservation of this species

The RAMPE

RAMPE is the Spanish acronym of the Red de Áreas Marinas Protegidas de España (Spanish network of marine protected areas; Ley 41/2010, del 29 de diciembre, de protección del medio marino). The RAMPE contains the marine protected areas in Spain and its main objective is to ensure the protection, conservation and recovery of the Spanish natural heritage and marine biodiversity. The areas in the RAMPE are subject to different categories of protection: marine protected areas, special areas of conservation, special protection areas for birds, sites of community importance and marine reserves, among others (

What is the main objective of the GAUDIN project?

“GAUDIN: Audouin’s gull as a tool to improve the management of the in the Spain’s east coast” is a project developed by our team, the Seabird Ecology Lab, from the Biology Faculty and the Institute for Research on Biodiversity (IRBio) from the University of Barcelona, with the collaboration of Asociación de Naturalistas del Sureste (ANSE) and the Spanish Institute of Oceanography (IEO).

During this project, we have investigated the role of RAMPE in the conservation of the Audoun’s gull (Ichtyaetus audouinii; Figure 2) in the Spain’s east coast, considering how, where and when they interact with fishing vessels. Moreover, we have taken into account the age class of the gulls (adults and juveniles) in the study of the use of RAMPE and in the interactions with fishing vessels.

GAUDIN, in the framework of the 2019 call of the “ayudas por la Fundación Biodiversidad F.S.P, en régimen de concurrencia competitiva, para la conservación de la biodiversidad marina en España”, has the support of Fundación Biodiversidad from the Ministry for the Ecological Transition and the Demographic Challenge.

How do we study the movement of Audouin's gulls? And their interactions with fisheries?

To address the movement of Audouin’s gulls and their interactions with fishing vessels, we used tracking data from both the gulls and the vessels. On one hand, we used remote tracking devices (GPS/GSM), which are extremely useful to study the movements and distribution of seabirds (among other animals), because they register the animal’s location every few minutes, allowing us to study how they use the RAMPE and how they interact with fishing vessels. For this purpose, we monitored 15 Audouin’s gulls in 2020, both adults and juveniles (Figures 3 and 4), especially during spring and summer, when they incubate their eggs, rear their chicks and start their migration. The studied gulls were captured and equipped with GPS/GSM devices in the Parque Regional Salinas y Arenales de San Pedro del Pinatar (Figure 5), a protected natural space of the Region of Murcia.

On the other hand, a novel algorithm allowed us to detect situations in which a bird is interacting with a vessel (bird and vessel are separated by maximum 1.5 km, and the interaction lasts longer than 10 min while the bird is flying at a low speed, indicating that it is probably feeding). This algorithm, developed in the framework of another project that we carried out in 2020-2021 (AMARYPESCA, supported by Fundación Biodiversidad and with EMFF funds), uses 1) tracking data from the vessel monitoring system (VMS), as well as tracking data from GPS devices carried by fishing vessels from collaborator fishermen, and 2) tracking data from Audouin's gulls equipped with GPS/GSM devices.

Results and management suggestions for the RAMPE and fishing activities

Results indicate that a 30% of the at sea-positions of adult Audouin's gulls and a 34% of the at sea-positions of juvenile gulls took place inside one of the RAMPE spaces (Figure 6). In general, the marine areas most used by both the adult and juvenile gulls (Figures 7 and 8) are near the coastline and are partially protected by the RAMPE, which is relevant for the conservation of the species.

Regarding the interactions with fishing vessels, the vast majority of interactions (92%) between Audouin’s gulls and the vessels (VMS data) occurred with the purse-seine fleet (during the night) and the trawl fleet (during the day), and in working days. With respect to age, the amount of interactions with both fleets were similar for adult gulls, but juvenile gulls interacted more frequently with trawlers (Figure 9 and 10). The purse-seine and trawl fleets are the most covered by the VMS, operate mainly in working days, and both offer food resources for seabirds. On the contrary, interactions with the pelagic longline and artisanal fleets were the least frequent for both age classes.

In general, the interactions between Audouin’s gulls and fishing vessels occurred outside the RAMPE. Only a fifth of the interactions detected for adult gulls (21%) and a third of the interactions detected for juvenile gulls (32%) took place inside the RAMPE.

Since the RAMPE covers an important part of the coastal waters used by Audouin’s gulls in the southern half of Spain, and most of the gull foraging trips – when feeding at sea – were close to the coastline, the RAMPE can be a good tool to protect the areas most used by the studied gulls, and therefore an useful tool for their conservation. However, most RAMPE areas lack management measures aimed at protecting seabirds in the marine environment or at reducing the human activities developed there (fishing, aquaculture, maritime traffic, tourism or leisure activities; with the exception of marine reserves). In light of these results, there is a need to design and implement management plans to regulate certain human activities in the RAMPE spaces most used by these gulls, at least during their breeding period and the beginning of their migration. It is also needed to implement mitigation measures to reduce seabird bycatch in fishing vessels that operate in coastal areas, both inside and outside the RAMPE, mainly in the Spain’s east coast.

Despite Audouin’s gull has recovered from population declines over the last decades, it still has a limited distribution and most individuals breed in Spain, so there is a need to continue monitoring the populations, evaluating the risks, and designing appropriate conservation measures.

Maps developed by Raquel Castillo.