The pearly razorfish (Xyrichtys novacula), commonly known as raor in the Balearic Islands, is a wrasse within the family Labridae. This fish species has particular biological and socio-cultural characteristics making it an ideal model organism in the fields of behavioural ecology, molecular ecology and conservation biology. In this study, we present the first annotated chromosome-level assembly for this species. Sequencing involved a combination of long reads with Oxford Nanopore Technologies, Illumina paired-end short reads (2 × 151 bp), Hi-C and RNA-seq from different tissues. The nuclear genome assembly has a scaffold N50 of 34.33 Mb, a total assembly span of 775.53 Mb and 99.63% of the sequence assembled into 24 superscaffolds, consistent with its known karyotype. Quality metrics revealed a consensus accuracy (QV) of 42.92 and gene completeness > 98%. The genome annotation resulted in 26,690 protein-coding genes and 12,737 non-coding transcripts. The coding regions encoded 39,613 unique protein products, 93% of them with assigned function. Overall, the publication of the X. novacula's reference genome will broaden the scope and impact of genomic research conducted on this iconic and colourful species., Funding for this project was provided by the Institut d’Estudis Catalans under the Catalan Initiative for the Earth Biogenome Project (PRO2021-S02-Barceló to MBS). MBS received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. WildFishGenes-891404. Additional funding was provided by the Spanish National Research Council and the METARAOR R&D Project (Grant num. PID2022-139349OB-I00) funded by the MICINN., Peer reviewed

© 2023 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/), Successful marine spatial planning relies on understanding patterns of human use, with accurate, detailed, and up-to-date information about the spatial distribution of fishing effort. In commercial vessels, tracking systems like the vessel monitoring system (VMS) or the automatic identification system (AIS) have helped to maintain and enhance the biodiversity of areas by generating large sources of positional data that served for commercial marine spatial planning. However, there is no regulation regarding location systems such as VMS or AIS for marine recreational fishing boats. Obtaining spatial data on marine recreational fishing can be difficult and time-intensive given the widespread and variable nature of the fleet. Remote cameras and computer vision systems are increasingly used to overcome the cost limitations of these conventional methods. Here we show a novel high-resolution and low-cost tracking system based on photo time-lapses and state-of-the-art computer vision algorithms, including deep learning, to automatically classify and obtain precise trajectories of fishing and cruising boats in coastal areas. Our method contributes to the automatic surveillance of marine protected areas by providing an image-based tool for automatic, real-time monitoring. Our method also allows for determining the intensity and spatial-temporal distribution of recreational fishing effort, important to defining the sustainability of the activity and coastal areas. We finally discuss the opportunities and limitations of computer vision tools applied to marine recreational fisheries spatial planning., The present research was carried out within the framework of the activities of the Spanish Government through the "Maria de Maeztu Centre of Excellence" accreditation to IMEDEA (CSIC-UIB) (CEX2021–001198). This work received funding from the METARAOR project (grant no. PID2022–139349OB-I00), JSATS PIE project (grant no. PIE202030E002) funded by MCIN/AEI/10.13039/501100011033 and AutoNatura 2000 Tres founded by the Fundación Biodiversidad (PLEAMAR program)., With funding from the Spanish government through the ‘María de Maeztu Unit of Excelence’ accreditation (CEX2021-001198-M)., Peer reviewed

Data and codes developed in this article are available in our repository https://github.com/Iremoma/DEB_IndividualVariability-Palmer-et-al.2024., Population dynamics is influenced by between-individual variability. Dynamic Energy Budget (DEB) theory is an appealing framework for assessing such a variability, yet DEB parameters have rarely been estimated at the individual level. Bayesian hierarchical models show promise for inferring individual variability in DEB parameters, thought computational challenges have limited their use due to the need to solve differential equations. Timely, Stan has emerged as a general-purpose statistical tool for fitting dynamic models. This paper introduces an analytical strategy using Bayesian parametric inference and hierarchical modelling to estimate individual-specific DEB parameters. Two biologically relevant DEB parameters were successfully estimated for 69 Gilt-head breams (Sparus aurata) with up to 11 measures of length and wet weight each. The estimated between-individual variability in these two DEB parameters explained well the observed patterns in length and weight at between- and within-individual levels. Moreover, data-simulation experiments highlighted the potential and limitations of our approach, suggesting that improved data collection could enable to increase precision and the number of DEB parameters that can be estimated at the individual level. This strategy can better represent between-individual variability in DEB parameters, which ultimately may improve forecasting of population dynamics after integrating DEB into population models., This work has been developed within the framework of the CDTI project IDI 20220242, which is part of the research line of innovation in aquaculture convened by the Centre for Technological Development and Innovation of Spain (CDTI) and co-financed by the European Maritime and Fisheries Fund (FEMP). Additional funding was provided by the METARAOR Project (Grant num. PID2022-139349OB-I00) funded by MCIN/AEI/10.13039/501100011033 and by “ERDF A way of making Europe”. IMM was founded by FPI-INIA-2020 PRE2020-093901 and JTF was founded by FPI-INIA-2019 PRE2019-091411. ACC was founded by the Research Council of Norway (RCN-project nr. 315051)., Peer reviewed

[Background] The lack of compatibility between acoustic telemetry equipment from different manufacturers has been a major obstacle to consolidating large collaborative tracking networks. Undisclosed encrypted signal coding protocols limit the use of acoustic telemetry to study animal movements over large spatial scales, reduce competition between manufacturers, and stifle innovation. The European Tracking Network, in collaboration with several acoustic telemetry manufacturers, has worked to develop new transparent protocols for acoustic tracking. The results are energy-efficient transmission protocols accessible to all researchers and manufacturers. Today, the Open Protocols (OP) are already available to manufacturers and developers, and the first transmitters and receivers to implement them are already in the water., [Results] The main objective of this study was to confirm the compatibility between devices from different manufacturers using OP, characterise the acoustic range of each transmitter–receiver manufacturer combination, compare the detection efficiency to the standard protocols used at present (R64K and encrypted protocols), and assess its robustness against spurious detections. An international collaborative effort was made to conduct acoustic range tests in four main aquatic habitats: a river, a coastal lagoon, a coastal habitat, and the open sea. Receivers and transmitters from different manufacturers were deployed at increasing distances from each other using the same experimental design at each location. The decay of detection probability with distance was modelled for each transmitter–receiver manufacturer combination by applying logistic regression using a Bayesian approach. Furthermore, to thoroughly assess performance differences in an applied research context, we conducted a direct field comparison between groups of smolts tagged with OP and R64K tags, tracking their migration to the sea., [Conclusions] Our results confirm full compatibility between the tested devices, with negligible differences in the measured acoustic ranges between OP manufacturers and when compared to encrypted protocols. The OP was also robust against spurious detections, and the field comparison between OP and R64K showed equal performance. We hope these novel insights will encourage international research groups to promote OP-based studies to ensure compatibility and maximise the benefits of acoustic telemetry networks., Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. This article is based upon work from the European Aquatic Animal Tracking Network COST Action (CA18102), supported by COST (European Cooperation in Science and Technology). EA was supported by a Vicenç Mut postdoctoral grant (ref. PD/041/2021) and the COREMAR project (ref. BIO011B-5819/23), funded by the Government of the Balearic Islands and the European Union (Next Generation EU). DA acknowledges FCT support through the transitional norm DL57/2016/CP1361/CT0036 and projects UIDB/04326/2020, UIDP/04326/2020 and LA/P/0101/2020. KBG and KA acknowledge support from the Danish Fishing Licences fund for the smolt study. JA received funding from the METARAOR Project (Grant num. PID2022-139349OB-I00) funded by MCIN/AEI/10.13039/501100011033/FEDER, UE. The present research was carried out within the framework of the activities of the Spanish Government through the ‘Maria de Maeztu Centre of Excellence’ accreditation to IMEDEA (CSIC-UIB) (CEX2021-001198)., With funding from the Spanish government through the "Severo Ochoa Centre of Excellence" accreditation (CEX2021-001198)., Peer reviewed

Acoustic telemetry (AT) has emerged as a valuable tool for monitoring aquatic animals in both European inland and marine waters over the past two decades. The European Tracking Network (ETN) initiative has played a pivotal role in promoting collaboration among AT researchers in Europe and has led to a significant increase in the number of tagged and observed aquatic animals in transboundary European waters. While AT benefits decision-making and delivers essential data to management bodies, its potential for management decision-making mechanisms has yet to be fully harnessed. We reviewed existing research, studies, and organisational initiatives related to aquatic animal tracking and their utility in fisheries management in European waters. We found that AT has already contributed to many aspects of fisheries management, such as improved understanding of stock dynamics, identification of critical habitats, assessment of migration routes, and evaluation of the effectiveness of conservation measures. However, broader utilisation of tracking technologies is needed. By leveraging the full potential of AT, managers can make more informed decisions to protect, restore, and sustainably manage European waters and creatures that live therein., This publication represents a collaborative effort from the European Tracking Network and is based upon work from COST Action—The European Animal Tracking Network (CA18102), supported by COST (European Cooperation in Science and Technology, www.cost.eu). Additionally, J. Reubens acknowledges support from the Research Foundation Flanders (FWO) as part of the Belgian contribution to LifeWatch. M. Prchalová and M. Říha are grateful for the support provided by the project nos. QK23020002 and QK21010131. J. Alós received funding from the METARAOR Project (grant no. PID2022-139349OB-I00) funded by MCIN/AEI/10.13039/501100011033/FEDER, UE. D. Abecasis was funded by the Fundação para a Ciência e a Tecnologia through UIDB/04326/2020, UIDP/04326/2020, LA/P/0101/2020, and DL57/2016/CP1361/CT0036., Peer reviewed

We analyse gender differences in recreational fisheries, using randomly collected data from Spain as a case study. Specifically, we contrast the participation rate, socioeconomic profile, self-determined motivations, and two wildlife-related value orientations (WVOs) among active (fished in the last 12 months) and lapsed (not fished in the last 12 months and without an intent to do so in the future) females and males participating in Spanish recreational fisheries, assessed via a nationwide telephone survey. Active participation rates in recreational fishing were significantly greater among males (21.5 % of the male population) than among females (11.7 % of the female population). Similar differences were also observed for lapsed participants. Active female recreational fishers were, on average, significantly younger (average 37 years) than their male counterparts (45 years), but other socioeconomic variables, such as residency in urban/rural settlements, income, or educational degree, did not differ. While the socioeconomic profile between active and lapsed male participants did not vary strongly, lapsed female participants in recreational fishing were older than active female participants, and had significantly lower income and degree of education. Female participants attributed significantly greater importance to engage with family than males as a motivation to recreate. Females also expressed greater importance to motives related to learning, discovering something new, and reflecting on one's identity and past good times than males. While the motivations between active and lapsed females were largely similar, the motivations between active and lapsed male participants were substantially different: active male recreational fishers placed significantly greater importance on taking risks, testing equipment, competing with others and teaching others than lapsed males. The WVOs of female and male participants in recreational fisheries were largely similar, but in lapsed fishers the mutualism score was significantly greater in females than males. Our study confirms the finding that the participation rate in recreational fishing is lower in females compared to males, and that males and females who made the decision to become active recreational fisheries share many motivations and values related to the use of wildlife and fish. That said, active female recreational fishers in Spain see fishing as a stronger contributor to family-related recreation than men., Funding of this work was provided by the METARAOR Project (Grant num. PID2022-139349OB-I00) funded by MCIN/AEI/10.13039/501100011033/FEDER, UE. The research was carried out within the framework of the activities of the Spanish Government through the "Maria de Maeztu Centre of Excellence" accreditation to IMEDEA (CSIC-UIB) (CEX2021-001198)., With funding from the Spanish government through the "Maria de Maeztu Centre of Excellence" accreditation (CEX2021-001198)., Peer reviewed

To effectively manage and conserve coastal ecosystems, accurate spatial data on marine recreational activities are crucial. This study introduces a deep-learning-based system designed for real-time detection and tracking of recreational vessels in coastal environments using cameras. We fine-tuned and evaluated two object detection and classification algorithms, YOLOv5 and YOLOv7, for automated, real-time vessel detection, classification and positioning within Marine Protected Areas (MPAs). Additionally, we optimized two multiple object tracking algorithms, StrongSORT and ByteTrack, for tracking the movements of the detected vessels in sequential timeframes. We implemented the best combination (YOLOv5 and ByteTrack) on an NVIDIA Jetson platform, an edge computing device specifically designed for AI applications, conducting thorough benchmarking across various simulated hardware configurations to determine its minimal computational and power needs. Then, we conducted field tests by positioning the system on a coastal cliff overlooking a recreational fishery located in a partial MPA. These tests aimed to validate the system's real-time operational viability and to acquire precise vessel trajectories. The results confirmed the system's efficacy and its data collection capabilities within a real marine environment. Finally, we evaluated two camera calibration techniques for converting image trajectories to geographic coordinates: a projective transformation with homography for accurate perspective adjustment, and an innovative neural network-based approach. The system we have developed could markedly enhance the monitoring and surveillance capabilities within MPAs, generating spatial-temporal data of recreational fishing effort that can be easily transferred to other case studies., The present research was carried out within the framework of the activities of the Spanish Government through the "Maria de Maeztu Centre of Excellence" accreditation to IMEDEA (CSIC-UIB) (CEX2021-001198). This work received funding by the METARAOR Project (Grant num. PID2022-139349OB-I00) funded by MCIN/AEI/10.13039/501100011033/FEDER, UE. Eugenio Cutolo was supported by the French National Research Agency (ANR-21-CE46-0011-01), the Bryttany region government (22006858), within the program Stratégie d’Attractivité Durable 2022, and the Finistère department government, within the program Aide aux Projets de Recherche 2022. Additional acknowledgements go to AtalaIA Detection Technologies (Atalaia, 2025) for their support in hardware benchmarking and providing essential AI software and computational resources., With funding from the Spanish government through the "Maria de Maeztu Centre of Excellence" accreditation (CEX2021-001198)., Peer reviewed

12 pages, 2 tables, 2 figures, Acoustic telemetry offers valuable opportunities to investigate individual variability in circadian-related and other behaviours and how environmental cues shape these patterns in wild fish populations. However, this potential has not yet been fully exploited. We conducted a meta-analysis on 44 datasets from 34 distinct marine and freshwater species and different types of data (acoustic detections, depth, acceleration and positioning). Our aim was to explore the potential of acoustic telemetry in identifying chronotypes as consistent among-individual differences in circadian-related behaviours. First, we applied hidden semi-Markov models to classify individual time series into active and rest states. Subsequently, we computed two classical circadian-related behavioural traits: awakening time (as the activity onset) and rest onset (as the activity offset). Subsequently, we identified distinct phenotypes by decomposing behavioural variation into within- and among-individual components based on repeatability scores. We found evidence of distinct chronotypes in 17 species, with average repeatability scores of 0.52 for awakening time and 0.43 for rest onset, revealing that chronotypes are common in aquatic species. Our findings highlight that both the data type, particularly acceleration sensors, and the number of detections are effective tools for exploring chronotypes. Our study proposes a novel approach to characterising daily activity patterns in aquatic species, predominantly in fishes, and provides guidelines for investigating chronotypes across diverse taxa. We emphasise the promise of biotelemetry and advanced statistical models for improving our understanding of the behaviour of aquatic species and highlight the value of synthesising across large data sets collected in networks of biotelemetryprojects, This work was supported by MCIN/AEI/10.13039/501100011033/FEDER, EU, CLOCK Project (Grant No. PID2019-104940GA-I00), Research Foundation Flanders (FWO), María de Maeztu Centre of Excellence (CEX2021-001198), the Leibniz-Community within the Pact for Innovation and Research (BTypes project) and the German Ministry of Education and Research (grant no.033W024A), Ministerio de Ciencia, Innovación y Universidades, Spanish Governments. MCIN/AEI/10.13039/501100011033 and by the European Union NextGeneration EU/PRTR (RYC2021-032594-I), METARAOR Project (Grant No. PID2022-139349OB-I00), MCIN/AEI/10.13039/501100011033/FEDER, EU, Vicenç Mut postdoctoral grant (PD/041/2021), FPI predoctoral fellowship from the Direcció General d'Innovació i Recerca of the Balearic Islands Government (Ref. FPI/2167/2018), The Research Council of Norway, CODCHANGE, CodChange, Axencia Galega de Innovación (GAIN) (IN607D 2023/007), COST Action – The European Animal Tracking Network, CA18102. The Czech National Agency for Agricultural Research (project no. QK23020002 'Pikeperch fry production, and their adaptabiliy and optimization of their stocking into open waters'). The Ministry of Agriculture af the Czech Repubic (project no. QK21010131 “Optimization of the management in carp ponds with 1-year production cycle in terms of co-feeding methods and mass balance”), Peer reviewed

Ocean mesoscale variability, including meanders and eddies, is a crucial component of the global ocean circulation. The Eddy Kinetic Energy (EKE) of these features accounts for about 90% of the ocean's total kinetic energy. This study investigates if the global ocean mesoscale variability is becoming more energetic by analyzing 30 years of satellite altimetric observations. We use two observational products: one constructed from a consistent pair of altimeters and another including all available missions. Our results reveal a significant global EKE strengthening of 1-3% per decade. The intensification is concentrated in energetic regions, particularly in the Kuroshio Extension and the Gulf Stream, which show EKE increases of ~ 50% and ~ 20%, respectively, over the last decade. These observations raise new questions about the impact of the Gulf Stream strengthening on the Atlantic meridional overturning circulation (AMOC) and challenge existing climate models, emphasizing the need for improved representation of small-scale ocean processes., B. B.-L. and A. P. acknowledge funding from the EuroSea project, funded by the European Union’s Horizon 2020 research and innovation programme under grant agreement No 862626. B. B.-L. is funded by the Balearic Government Vicenç Mut program (Grant number PD/008/2022) and acknowledges support from the METARAOR project (Grant number PID2022-139349OB-I00) funded by MCIN/AEI/10.13039/501100011033/FEDER, EU. A. P., B. B.-L., and V. C. acknowledge support from the FaSt-SWOT project (Grant number PID2021-122417NB-I00) funded by the Spanish Ministry of Science, Innovation, and Universities, the Spanish Research Agency, and the European Regional Development Fund (MCIN/AEI/10.13039/501100011033/FUE). P. R. was supported by a JAE-Intro scholarship issued by the Spanish National Research Council (CSIC). V. C. acknowledges support from the Ramón y Cajal Program (RYC2020-029306-I) and from the European Social Fund/Universitat de les Illes Balears/Spanish State Research Agency (AEI—https://doi.org/10.13039/501100011033). All authors acknowledge funding from the "Copernicus Marine Service Sea Level Thematic Assembly Center" (SL-TAC) project, funded by the Copernicus Marine Service (CMEMS), and from the “Ocean observations and indicators for climate and assessments” (ObsSea4Clim) project, funded by the European Union, Grant Agreement number 101136548, DOI: 10.3030/101136548, contribution nr. 2. This study was carried out within the framework of the activities of the Spanish Government through the “María de Maeztu Centre of Excellence” accreditation to IMEDEA (CSIC-UIB) (CEX2021-001198)., With funding from the Spanish government through the "Maria de Maeztu Centre of Excellence" accreditation (CEX2021-001198)., Peer reviewed

The high spatial-temporal variability in fishing effort, combined with the difficulty of monitoring individual activities, hampers effective management of recreational fisheries. Angler smartphone applications (apps) offer a promising digital tool for self-reporting of fishing effort (E) and catch per unit of effort (CPUE). However, despite their growing use for data collection in recreational fisheries, the existing literature on their performance remains limited, raising concerns about potential biases in the data. Since 2019, daily trips inside the 12 partially protected Marine Protected Areas (MPAs) of the Balearic Islands (Spain) must be self-reported via the “Diari de Pesca Recreativa” app (the App), recording fishing E and CPUE. This study aimed to evaluate the App's performance in reporting recreational fisheries data over a six-year period. Data obtained via the App (3672 trip self-reports) were compared to data collected through a standard method (360 on-site creel surveys). Importantly, the App represents complete fishing trips, whereas creel surveys record only partial trips, as they are conducted mid-activity. This methodological difference in trip duration reporting was expected to influence estimates of E (hours · angler · trip) and possibly CPUE (catch · E⁻¹). These estimates were compared across datasets overall, as well as stratified by month, fishing type, MPA, and for key target species. Data from the App tended to overestimate E, while creel surveys underestimated it, and significant differences were observed between whole datasets for E and CPUE. However, when stratified, most groups showed no statistically significant differences in E and CPUE estimates. With these generally comparable results, and given that the limitations of one are offset by the strengths of the other, combining both data sources will improve reliability. The App not only generates a higher volume of trip data but also digitizes data collection through a user-friendly platform for self-reporting, enabling automation and analytics for fisheries monitoring and management of recreational fisheries. Because reporting was mandatory in this case, biases commonly associated with voluntary apps (e.g. avidity, age bias) are unlikely to apply, making this study particularly relevant for assessing the utility of mandatory app-based data in fisheries management., This work has been funded by the project (MEPRO 5220/2023 (REMAR). Josep Alós received funding from the METARAOR Project (Grant num. PID2022–139349OB-I00) funded by MCIN/AEI/10.13039/501100011033/FEDER, UE. We would like to thank Eneko Aspillaga for his helpful input to this work, as well as all of the recreational fishers involved in the study. We also thank the reviewers for their insightful comments during peer review, which noticeably improved the manuscript. The present research was carried out within the framework of the activities of the the Spanish Government through the "Maria de Maetzu Centre of Excellence" accreditation to IMEDEA (CSIC-UIB) (CEX2021-001198)., With funding from the Spanish government through the "Maria de Maeztu Centre of Excellence" accreditation (CEX2021-001198)., Peer reviewed

Ocean currents are crucial in regulating Earth's climate, with a significant impact in the distribution of ocean properties. During the Calibration/Validation phase of the Surface Water and Ocean Topography (SWOT) satellite mission, we performed a high-resolution, multi-platform experiment to evaluate SWOT's ability to resolve small-scale features, focusing on a ∼25 km-radius anticyclonic eddy in the Western Mediterranean Sea. Acoustic Doppler Current Profiler (ADCP) recorded maximum velocities of 30 cm/s at 155 m depth and underwater glider data identified biconvex isopycnals, classifying the eddy as intrathermocline. SWOT successfully captured the sea level signal and surface geostrophic currents of the eddy, showing notable error reduction over conventional altimetry: 24% in sea level representation compared to glider observations, and 35% and 31% in horizontal velocity magnitude compared to Acoustic Doppler Current Profiler and drifter measurements, respectively. This study highlights SWOT's potential in resolving small-scale ocean dynamics., This study is funded by the Spanish Ministry of Science, Innovation, and Universities (MICIU), the Spanish Research Agency (AEI), the European Regional Development Fund (Grant PID2021-122417NB-I00 by MCIN/AEI/10.13039/501100011033/FUE/NextGeneration/PRTR), and conducted at IMEDEA's María de Maeztu Centre of Excellence from AEI/MICIU (CEX2021-001198). Additional support comes from the SWINT project (CNS2023-145542 by MCIN/AEI/10.13039/501100011033/NextGenerationEU/PRTR) and Copernicus Marine Service. ICTS SOCIB acknowledges support from MICIU, the Balearic Government, and CSIC. E.V.-M is funded through the FPU2022/02791 contract (MICIU). L.G.-N. through a Margarita Salas fellowship (European Union-NextGenerationEU, MICIU, and the Recovery, Transformation, and Resilience Plan via University of the Balearic Islands). B. B.-L. is funded by the Balearic Government Vicenç Mut program (Grant PD/008/2022) and acknowledges METARAOR Project (Grant num. PID2022-139349OB-I00) funded by MCIN/AEI/10.13039/501100011033/FEDER. EC is supported by French National Research Agency (ANR-21-CE46-0011-01), Brittany government under Stratégie d’Attractivité Durable 2022, Finistère government under Aide aux Projets de Recherche 2022, and ISblue project (ANR-17-EURE-0015). We acknowledge the SOCIB R/V crew for their essential support in FaSt-SWOT experiment., With funding from the Spanish government through the "Maria de Maeztu Centre of Excellence" accreditation (CEX2021-001198)., Peer reviewed

14 pages, 4 figures, 3 tables, Acoustic telemetry has become an essential tool for studying activity patterns of animals in aquatic environments. Activity is typically recorded using transmitters with integrated sensors or dense receiver arrays for positional tracking. While effective, these approaches are financially and logistically expensive due to the need for advanced transmitters or a large number of acoustic receivers.
This study presents a novel methodology to quantify activity patterns from single-receiver acoustic telemetry setups. Our method extracts the time of arrival (TOA) of acoustic signals and estimates the relative distance between the individual and the receiver. By examining variations in TOA-based distances, movement parameters such as step lengths can be calculated, which can then be used to classify behavioural states through hidden Markov models or other statistical approaches.
We validated our approach through a positioning test and demonstrated its effectiveness in inferring behavioural states across multiple species by analysing six acoustic telemetry datasets. The validation also included a comparison between TOA-based distances in multiple receivers and a positioned telemetry dataset.
Our method proved to be effective in estimating the distance between transmitters and single receivers, as well as characterising the activity patterns of the analysed species. It is particularly effective for species with certain site fidelity, where movement relative to a fixed receiver can provide significant insights into activity patterns. The method can also be applied in analysis workflows to check post-tagging or natural mortality by identifying stationary transmitters. By providing a cost-efficient method, this approach will enable detailed behavioural studies in a wide range of species and contexts, leveraging minimum equipment availability, The Balearic Tracking Network acoustic telemetry array was supported by the COREMAR project (BIO011B-5819/23), funded by the Government of the Balearic Islands and the European Union (PRTR, NextGenerationEU). Tagging of common dolphinfish was funded by the CORYTRACK project (CTA070.003, MAVA Grants, Marine Stewardship Council). The Cíes Archipelago acoustic telemetry array and the tagging of the undulate skate were supported by the ATLAZUL project (0755_ATLAZUL_6_E) co-funded by the European Regional Development Fund (ERDF) through the Interreg V-A Spain–Portugal Program (POCTEP) 2014–2020. This work was also developed with the support of the Program of Marine Sciences of Galicia as part of the Complementary Plans of Science of the Spanish Ministry of Science and Innovation included in the Recovery Plan of Transformation and Resilience (PRTRC17.I1), funded by the Xunta de Galicia through the NextGenerationEU and the European Maritime, Fisheries and Aquaculture Fund (EMFAF). Eneko Aspillaga was supported by a Vicenç Mut postdoctoral grant (PD/041/2021) funded by the Government of the Balearic Islands. David Villegas-Ríos was supported by a Ramón y Cajal Contract (RYC2021-032594-I) funded by the Spanish Ministry of Science, Innovation and Universities MCIN/AEI/10.13039/501100011033 and the European Union NextGeneration EU/PRTR. Josep Alós received funding from the METARAOR Project (PID2022-139349OB-I00) funded by MCIN/AEI/10.13039/501100011033/FEDER, UE. Vicenç Moltó was supported by a Horizon Europe Marie Skłodowska Curie Action (Postdoctoral Fellowship, project number 101153501), funded by the European Union. IMEDEA is an accredited ‘María de Maeztu Unit of Excellence’ (Grant CEX2021-001198, funded by MICIU/AEI/10.13039/501100011033), Peer reviewed

Marine heatwaves (MHWs) are defined as discrete periods of anomalous ocean warming. In the most commonly used MHW determination method, the threshold over which a certain temperature is considered to be an MHW is calculated using a fixed baseline constructed from a common climatology (1982–2011). By this definition, these phenomena have been increasing in frequency and intensity due to global warming, and this is expected to ultimately lead to a saturation point. Significant efforts have been directed towards developing new ways of defining marine heatwaves, motivated by the need to differentiate between long-term temperature trends and extreme events. The Mediterranean Sea serves as an ideal backdrop for comparing different MHW detection methods due to its rapid response to climate change, with higher warming trends than the global ocean. In this work, we evaluate sea surface temperature trends in the Balearic Sea, a subregion of the western Mediterranean, and compare the fixed-baseline MHW detection method with two recently developed alternative methodologies. The first alternative employs a moving climatology to adjust the baseline, while the second method involves detrending the temperature data before detecting MHWs with a fixed baseline. For the period between 1982 and 2023, our analysis reveals a statistically significant warming trend of 0.036 ± 0.001 °C per year, which represents an increase of ∼ 10 % compared to previous studies in the same region due to the inclusion of two particularly warm recent years, 2022 and 2023. Regarding MHWs, all three methods identify major events in 2003 and 2022. However, the fixed-baseline method indicates an increase in MHW frequency and duration over time, a tendency not detected by the other methodologies, since we isolate the extreme events from the long-term warming trend. This study underscores the importance of selecting an appropriate MHW detection method that aligns with the intended impact assessments. Studies performed with a moving baseline or detrended data could be more appropriate to analyse species with higher adaptability, while a fixed baseline could be a better option to study species that are less adaptable and more sensitive to exceeding a critical temperature threshold., This study is contribution number 14 to the project ObsSea4Clim (“Ocean observations and indicators for climate and assessments”) funded by the European Union (grant no. 101136548). Blanca Fernández-Álvarez received support first through a JAE-Intro scholarship granted by the Spanish National Research Council (CSIC) (grant no. JAEINT_23_01447) and later by a FPU grant by the Spanish Ministry of Science, Innovation and Universities (grant no. FPU23/01280). Bàrbara Barceló-Llull is funded by the Balearic Government Vicenç Mut programme (grant no. PD/008/2022) and received support from the METARAOR Project (grant no. PID2022-139349OB-I00) funded by MCIN/AEI/10.13039/501100011033/FEDER, UE. We also acknowledge the support of contract no. C3S2_520_CSIC/SC2 funded by the European Copernicus Climate Change Service (C3S) implemented by the European Centre for Medium-Range Weather Forecasts (ECMWF)., The article processing charges for this open-access publication were covered by the CSIC Open Access Publication Support Initiative through its Unit of Information Resources for Research (URICI)., Peer reviewed

METARAOR Project (Grant num. PID2022-139349OB-I00) funded by MCIN/AEI/10.13039/501100011033/FEDER, EU Vicenç Mut - CAIB postdoctoral grant (to MBS) FSE+ EU funds, project number PD-050-2023, Peer reviewed

Monitoring recreational fisheries is difficult: anglers are widely dispersed, gear and practices vary, and many species are involved, which leads to fragmented and scarce data. To address these issues, we developed an Artificial Intelligence (AI) pipeline that turns angler-reported photos into standardised records of catch composition and individual body lengths. The workflow consists of four steps: (i) automatic fish detection, (ii) pixel-accurate segmentation, (iii) species classification trained with few labelled images and (iv) length estimation calibrated with a measurement board carrying fiducial markers (machine-readable reference tags). We validated the system on smartphone images from a mixed-species fishery in the western Mediterranean under realistic conditions (variable lighting, occlusions, mixed catches). The detection–segmentation stage achieved F1≈0.93. The classifier reached 85% accuracy across 38 species using only 12 training images per species, showing strong data efficiency. Length estimates were robust, with centimetre-level error suitable for size-class analyses. Leveraging large, pre-trained foundation models, only a lightweight adapter requires training, keeping data and compute demands low and enabling rapid extension across regions, gear types and species lists. When integrated with existing catch-reporting smartphone applications and agency workflows, the pipeline delivers instant angler feedback and streams standardised, analysis-ready records to managers. In practice, this unlocks operational monitoring: near-real-time indicators of catch composition and length structure, automated size-limit compliance checks and cost-efficient inputs to stock assessment and adaptive management., This work was supported by Ministerio de Ciencia e Innovación, PID2022-139349OB-I00, MEPRO 5220/2023, CEX2021-001198, PRE2020-095580. Agence Nationale de la Recherche, ANR-21-CE46-0011-01. Conseil Régional de Bretagne, 22006858. Finistère Department. European Social Fund. European Regional Development Fund, PID2022-139349OB-I00., With funding from the Spanish government through the "Maria de Maeztu Centre of Excellence" accreditation (CEX2021-001198)., Peer reviewed

Understanding between-individual variability in energy acquisition is essential for elucidating many ecological processes in wild fish populations and for enhancing the efficiency of aquaculture production. This study explores whether individual variations in feed ingestion rates among group-reared fish can arise from intrinsic fish-specific, size-independent factors. Specifically, we quantify the residual variability in ingestion rate (i.e., the variability beyond body size effects and extrinsic influences) to assess the role of context-independent, stable, intrinsic behavioural differences that may lead to feeding hierarchies. We monitored the individual feeding behaviour of 48 European seabass adult females (Dicentrarchus labrax) externally tagged reared in sea cages (6 cages housing 8 fish each) under three feeding levels (two cages per level) over four months. Across 8 repeated feeding trials per cage, fish were offered feed pellets one at a time using an automated feeder, and their individual pellet consumption were video recorded. Using a Bayesian statistical model, we evaluated the fish-specific probability of pellet consumption as a function of body size, temperature, anthropogenic stress and feeding level, while accounting for variation across individuals and feeding trials. Our results showed: i) a substantial and consistent between-individual variability in ingestion rates across feeding trials, and ii) a relevant negative effect of anthropogenic stress on feeding activity. Notably, individual-specific effects, independent of body size and external variables, accounted for over 70% of the variance in ingestion rate, suggesting that intrinsic and stable behavioural differences, indicative of fish behavioural types, may play a central role in shaping feeding hierarchies., JTF and IMM were supported by a Ph.D. fellowship (FPI) from the Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA) (FPI-INIA-2019 PRE2019-091411 and FPI-INIA-2020 PRE2020-093901, respectively). This is a contribution of the Joint Research Unit IMEDEA-LIMIA. Funding was provided by the METARAOR Project (Grant num. PID2022-139349OB-I00) funded by MCIN/AEI/10.13039/501100011033/FEDER, UE; and the PREFISHFARM Project (Grant num. CPP2023-010949) funded by MICIU/AEI/10.13039/501100011033., Peer reviewed

[eng] Background: The lack of compatibility between acoustic telemetry equipment from different manufacturers has been a major obstacle to consolidating large collaborative tracking networks. Undisclosed encrypted signal coding protocols limit the use of acoustic telemetry to study animal movements over large spatial scales, reduce competition between manufacturers, and stifle innovation. The European Tracking Network, in collaboration with several acoustic telemetry manufacturers, has worked to develop new transparent protocols for acoustic tracking. The results are energy-efficient transmission protocols accessible to all researchers and manufacturers. Today, the Open Protocols (OP) are already available to manufacturers and developers, and the first transmitters and receivers to implement them are already in the water. Results: The main objective of this study was to confirm the compatibility between devices from different manufacturers using OP, characterise the acoustic range of each transmitter–receiver manufacturer combination, compare the detection efficiency to the standard protocols used at present (R64K and encrypted protocols), and assess its robustness against spurious detections. An international collaborative effort was made to conduct acoustic range tests in four main aquatic habitats: a river, a coastal lagoon, a coastal habitat, and the open sea. Receivers and transmitters from different manufacturers were deployed at increasing distances from each other using the same experimental design at each location. The decay of detection probability with distance was modelled for each transmitter–receiver manufacturer combination by applying logistic regression using a Bayesian approach. Furthermore, to thoroughly assess performance differences in an applied research context, we conducted a direct field comparison between groups of smolts tagged with OP and R64K tags, tracking their migration to the sea. Conclusions: Our results confirm full compatibility between the tested devices, with negligible differences in the measured acoustic ranges between OP manufacturers and when compared to encrypted protocols. The OP was also robust against spurious detections, and the field comparison between OP and R64K showed equal performance. We hope these novel insights will encourage international research groups to promote OP-based studies to ensure compatibility and maximise the benefits of acoustic telemetry networks.

[eng] Ocean mesoscale variability, including meanders and eddies, is a crucial component of the global ocean circulation. The Eddy Kinetic Energy (EKE) of these features accounts for about 90% of the ocean’s total kinetic energy. This study investigates if the global ocean mesoscale variability is becoming more
energetic by analyzing 30 years of satellite altimetric observations. We use two observational products: one constructed from a consistent pair of altimeters and another including all available missions. Our results reveal a significant global EKE strengthening of 1–3% per decade. The intensification
is concentrated in energetic regions, particularly in the Kuroshio Extension and the Gulf Stream, which show EKE increases of~50% and~20%, respectively, over the last decade. These observations raise new questions about the impact of the Gulf Stream strengthening on the Atlantic meridional
overturning circulation (AMOC) and challenge existing climate models, emphasizing the need for improved representation of small-scale ocean processes.

[eng] To effectively manage and conserve coastal ecosystems, accurate spatial data on marine recreational activities are crucial. This study introduces a deep-learning-based system designed for real-time detection and tracking of recreational vessels in coastal environments using cameras. We fine-tuned and evaluated two object detection and classification algorithms, YOLOv5 and YOLOv7, for automated, real-time vessel detection, classification and positioning within Marine Protected Areas (MPAs). Additionally, we optimized two multiple object tracking algorithms, StrongSORT and ByteTrack, for tracking the movements of the detected vessels in sequential timeframes. We implemented the best combination (YOLOv5 and ByteTrack) on an NVIDIA Jetson platform, an edge computing device specifically designed for AI applications, conducting thorough benchmarking across various simulated hardware configurations to determine its minimal computational and power needs. Then, we conducted field tests by positioning the system on a coastal cliff overlooking a recreational fishery located in a partial MPA. These tests aimed to validate the system's real-time operational viability and to acquire precise vessel trajectories. The results confirmed the system's efficacy and its data collection capabilities within a real marine environment. Finally, we evaluated two camera calibration techniques for converting image trajectories to geographic coordinates: a projective transformation with homography for accurate perspective adjustment, and an innovative neural network-based approach. The system we have developed could markedly enhance the monitoring and surveillance capabilities within MPAs, generating spatial-temporal data of recreational fishing effort that can be easily transferred to other case studies.

[eng] 1. Acoustic telemetry has become an essential tool for studying activity patterns of animals in aquatic environments. Activity is typically recorded using transmitters with integrated sensors or dense receiver arrays for positional tracking. While effective, these approaches are financially and logistically expensive due to the need for advanced transmitters or a large number of acoustic receivers. 2. This study presents a novel methodology to quantify activity patterns from single-receiver acoustic telemetry setups. Our method extracts the time of arrival (TOA) of acoustic signals and estimates the relative distance between the individual and the receiver. By examining variations in TOA-based distances, movement parameters such as step lengths can be calculated, which can then be used to classify behavioural states through hidden Markov models or other statistical approaches. 3. We validated our approach through a positioning test and demonstrated its effectiveness in inferring behavioural states across multiple species by analysing six acoustic telemetry datasets. The validation also included a comparison between TOA-based distances in multiple receivers and a positioned telemetry dataset. 4. Our method proved to be effective in estimating the distance between transmitters and single receivers, as well as characterising the activity patterns of the analysed species. It is particularly effective for species with certain site fidelity, where movement relative to a fixed receiver can provide significant insights into activity patterns. The method can also be applied in analysis workflows to check post-tagging or natural mortality by identifying stationary transmitters. By providing a cost-efficient method, this approach will enable detailed behavioural studies in a wide range of species and contexts, leveraging minimum equipment availability.