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- Reserve effect of a small North-East Atlantic marine protected area (Arrabida, Portugal) on soft-sediment fish speciesPublication . Martínez Ramírez, Lucas; Priester, Carl Robert; Sousa, Inês; Erzini, Karim; Abecasis, DavidThe implementation of marine protected areas (MPAs) has been widely used as a tool to manage and conserve marine resources and services. Yet, to date, the reserve effect is still weakly evaluated, particularly for soft-sediment habitats. The Arrabida MPA, considered as a biodiversity hotspot, was fully established in 2009 on the west coast of Portugal and is characterized by large expanses of soft-sediment habitats. This MPA was established to protect biodiversity and to ensure the livelihood of the local small-scale fisheries community. Beyond before-after-control-impact (BACI) analyses were carried out on catch data (abundance and biomass) of 351 trammel net sets from experimental fishing campaigns (2007-2019) to study the reserve effect on demersal fish populations. The results show a declining trend in abundance inside and outside the protected area, with significant positive effects only found for undersize commercial species and Solea senegalensis, and a general increase in fish species total length. Despite the lack of any obvious reserve effect, the increase in fish length can be considered as a first sign. Anthropogenic pressures are generalized around the area, and transgressions of the restrictions are frequently observed inside the no-take zone. These can, among other aspects, delay or prevent the expected reserve effects. Therefore, enforcement and/or modification of the spatial plan must be incentivized to achieve the goals of the MPA.
- Tagging mortality in acoustic telemetry studies: insights from a multispecies analysisPublication . Martínez Ramírez, Lucas; Bentes, Luis; Dias Almeida Cardoso, André Filipe; Erzini, Karim; Gandra, Miguel; Kraft, Sebastian; Winkler, Alexander; Abecasis, DavidThe widespread adoption of acoustic telemetry has transformed our understanding of marine species' behavior and movement ecology. However, accurately interpreting telemetry data, especially concerning tagging mortality, is essential for drawing valid conclusions. In this study, we scrutinized tagging mortality in 223 individuals across 14 species and evaluated the impact of tagging methodologies, including capture method and size effects. Results reveal high tagging survival rates overall, attributable to the resiliency of the studied species and the rigorous animal welfare protocols followed during tagging procedures. Our results highlight the importance of tailoring array designs to the specific mobility patterns of the studied species for accurate survival assessments. This research contributes to generalizing mortality assessments and clearing the path for more precise and reliable telemetry studies in the future.
- Movement patterns of the invasive atlantic blue crab in a northeastern atlantic estuaryPublication . Encarnação, João Pedro da Silva; Morais, Pedro; Abecasis, David; Martínez Ramírez, Lucas; Barra, Melissa; Baptista, Vânia; Carere, Claudio; Teodosio, MariaThe movement ecology of invasive species discloses critical information to estimate ecological impacts and inform management policies to control their spread. The Atlantic blue crab Callinectes sapidus Rathbun, 1896, has successfully invaded coastal and estuarine ecosystems in southern Europe, making it urgent to understand fundamental aspects of its ecology in the non-native range. Recent studies identified key prey species for the Atlantic blue crab and quantified niche overlap with other crab species; however, the areas where the impacts are likely to be greater remain unexplored. Thus, we aim at studying its spatial ecology and assess which areas of a tidal estuary (Guadiana, Portugal) are predominantly used by the invasive Atlantic blue crab through acoustic telemetry. A total of 24 specimens were collected in the estuary in 2022, tagged, and tracked for up to nine months using four acoustic receivers located at 1, 3, 11, and 20 km from the river mouth. Two predominant patterns were observed: 1) movements along the estuary synchronized with the tide, and 2) extended residency periods in the transition between the middle and upper estuary. These findings can now inform policy makers and be used to better design local management plans, namely in upper areas of the Guadiana estuary where the species tends to aggregate, making it easier to be targeted by artisanal fisheries, when compared to coastal areas.
- Movement patterns and connectivity of argyrosomus regius along the southwest coast of Portugal using network analysisPublication . Fanna, Samuele; Gandra, Miguel; Kraft, Sebastian; Martínez Ramírez, Lucas; Vilas, Cesar; Winkler, Alexander; Abecasis, DavidThe meagre (Argyrosomus regius) is a large teleost inhabiting the coastal waters of the East Atlantic Ocean and the Mediterranean Sea. Along the Iberian Peninsula, it is frequently targeted by both commercial and recreational fisheries. Despite its relevance, information on its population structure and movement ecology has been scarce until recently. While these studies have provided a foundation, information on the main migratory corridors along the coast is still missing. The current study aimed to identify primary migratory routes, aggregations, and residency sites along the Southwest coast of Portugal. Forty-nine adult meagres were captured and tagged with acoustic transmitters between 2018 and 2023. Their movement was monitored from 122 acoustic receivers, grouped into 25 arrays, which were deployed throughout the Gulf of C´adiz and along the Southwest coast of Portugal. A spatial network approach was applied to analyse these data. The locations near the tagging site and along the Southwest coast displayed high values of eigenvector and betweenness centralities, indicating their crucial role in facilitating the connectivity of adult meagre between the two regions. Furthermore, co-occurrences outside the spawning season highlight their role as potential feeding grounds. The number of detections and co-occurrences near the Guadiana Estuary provides further evidence that the location may serve as a spawning ground, although additional data are needed to confirm this. Our findings expand previous research, identifying key passages and aggregation sites for meagre along the coast. These results can inform management and conservation efforts, particularly in the context of marine spatial planning.