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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.