Fisheries bycatch is an important source of direct human-induced mortality for marine mammals worldwide. Despite its significance, monitoring and quantifying bycatch mortality remains challenging. The examination of stranded animals can provide key information to assess the importance of bycatch mortality, contributing to understanding its impact on populations, and identifying the fisheries responsible. However, the utility of data from strandings remains underexplored. Based on an expert consultation using a questionnaire carried out under the auspices of the International Council for the Exploration of the Sea Working Group on Marine Mammal Ecology, this study assessed the potential of stranding networks in Western Europe to support the assessment of marine mammal population status and impacts of stressors. The present paper (the second of two) focuses on information on bycatch collected from strandings, and its utility for monitoring and assessing bycatch mortality. Responses from 45 organizations in 19 countries indicated that extensive information on marine mammal bycatch mortality is collected and can sometimes be used to identify the species or populations most affected by bycatch, reveal spatio-temporal trends in bycatch mortality, and determine the fisheries and/or fishing gear involved. However, the survey identified several limitations that hinder the contribution of stranding data to bycatch impact monitoring and assessment. There is a need to strengthen data collection and reporting, especially for certain taxa and regions, and for wider adoption and harmonization of best practise protocols for diagnosing causes of mortality and understanding its context, e.g. by determining health status, estimating demographic parameters, helping to identify the fishing gears responsible for bycatch mortality, and appropriately communicating the degree of uncertainty associated with interpretations. Carcass drift models could enable stranding data to be used to estimate total bycatch mortality and contribute to assessing the impact on populations. The need for adequate baseline funding for stranding networks to carry out their activities and for streamlined data reporting was widely recognized. Achieving coordinated, harmonized, large-scale and long-term data and samples collection following best practices will be essential to ensure that data from strandings on bycatch mortality can be integrated into bycatch impact assessments to inform management.

Large-scale data synthesis is a foundation pillar of modern macroecology, necessary for transitioning fragmented regional data into scalable biosecurity frameworks. This study presents the outcomes of a coordinated nationwide effort to analyze marine Non-Indigenous Species (NIS) records across mainland Portugal, the Azores and Madeira archipelagos using a dual-framework design. Our goals were to update the morphologically confirmed NIS inventory, identify primary introduction pathways, examine temporal and spatial trends, and evaluate genetic database coverage. We delivered an updated checklist comprising 231 morphologically confirmed marine NIS, including five new regional records. Spatial analysis reveals distinct biogeographical divergence: mainland NIS predominantly originate from the temperate North Pacific, probably due to shipping and aquaculture vectors, whereas archipelago NIS originate from the North Atlantic. This pronounced regional variability in pathway dynamics underscores the need for spatially specific management rather than uniform national policies. Also, a systematic genetic gap analysis showed that 71% of these species are cataloged in global repositories, whereas only 12.5% feature locally sourced sequences. To bridge this gap, the second framework introduces a precautionary molecular watchlist of 22 species detected exclusively via DNA-based methods awaiting morphological confirmation. Ultimately, this dual-framework structure demonstrates how integrating taxonomy with provisional molecular data provides a reliable, data-driven baseline, while moving beyond a localized dataset update to offer a scalable reference frame capable of informing regional and global marine biosecurity frameworks.

Fishers and consumers recognise that there is important variation in the morphology and quality of the stalked barnacle Pollicipes pollicipes. Two extreme phenotypes can be identified: thick/short barnacles associated with a high commercial quality; and thin/long barnacles associated with low commercial quality. This work describes morphological/biochemical differences between the two extreme phenotypes, and investigate the main drivers causing these differences. The perception of the variation in quality and morphology of P. pollicipes by scientists and fishers was similar. The ratio of the width of the capitulum base to its total length (CB/TH) was used and validated as a good proxy variable for evaluating quality. There were no significant differences in the individual biomass of high and low quality barnacles. The biochemical composition of the edible part of P. pollicipes of high commercial quality barnacles presented a higher protein, energetic value and fat, and low commercial quality barnacles presented a higher water content. Regional differences were also detected in the biochemical composition of P. pollicipes. On the SW coast of Portugal (SW), barnacles presented a higher ash, protein and water content, and a lower glucose and energetic value, than in two regions of the centre coast. The influence of potential drivers of variation in morphology/quality of P. pollicipes was tested through a manipulative experiment. The results suggest that the elongation of P. pollicipes is related to the greater density of the barnacles on a group scale. Furthermore, the shortening of P. pollicipes may be related to the lower density of the barnacles at the group scale and to specific microhabitat environmental conditions, such as hydrodynamics. The variation in the quality/morphology of P. pollicipes that was recognized by fishers and scientists, was associated with a different biochemical composition. Density and specific local conditions were identified as drivers of this variation.

The study of stranded animals is a valuable aid to monitoring marine mammals globally. However, the utility of strandings data depends on their quality and representativeness, which is affected by various biological, physical, social and economic factors. An analysis of how stranding networks work could help understand limitations in the data collected and facilitate correcting for or even eliminating them. In 2021, the International Council for the Exploration of the Sea's Working Group on Marine Mammal Ecology carried out an expert consultation using a questionnaire to provide insight into the contribution of European stranding networks as a monitoring tool in European countries with Northeast Atlantic and adjacent coasts (hence also including some networks operating along the Mediterranean coast). A key aim was to identify ways to improve data on mortality of marine mammals due to fishery bycatch. The present paper is the first of a two-part series based on the responses to the questionnaire by 45 organisations from 19 countries, and focuses on characterising the activities and capacities of the stranding networks surveyed, identifying differences within and between countries, highlighting strengths and weaknesses, and providing recommendations to enhance the value and credibility of the information collected. The second paper will focus on the information specifically related to mortality due to fishery bycatch. Stranding networks provide extensive spatio-temporal coverage of European coastlines, but their activities may be constrained by limited resources as well as limitations imposed by the stranding process. There is a need for better coordination and standardisation of the collection and analysis of data and samples and increased spatial coverage to fill gaps. To improve data quality, in particular to support assessment of impacts of threats such as bycatch, more necropsies and associated sample analysis are needed. It would also be advantageous to collect more information from less fresh animals, record search effort, and give greater attention to pinnipeds and non-marine mammal taxa. We also highlight the need to make information available and the potential value of a common database. Streamlining the reporting of results at the European level and providing systematic funding to stranding networks in accordance with their needs are necessary steps to optimise their role as a tool for the long-term monitoring of marine mammals and other marine megafauna in Europe.

We have followed the recovery of gaps produced either by harvesters or by scientists in stands of stalked barnacle (Pollicipes pollicipes) during two years in four regions of Europe (SW Portugal, Galicia and Asturias in Spain and Brittany in France; n = 423 gaps), which was extended to four years in Asturias (n = 252 gaps). The presence of adult conspecifics in the margins of the gaps increased by at least four times the probability of initiation of their recovery. After two years of follow-up in the four regions, 90

In the framework of stock enhancement, field experiments were conducted between March and July 2021 in rocky shores of Central Portugal to test the usefulness of refuges and calcein marking for juvenile sea urchins releases. Individuals with 10–20 mm in test diameter were captured in nature and tagged through immersion in a calcein bath with a concentration of 150 mg L−1, during 48 hr. Artificial shelters were used to provide refuge and an acclimatization structure for the released sea urchins, and in situ monitoring was carried out by counting the marked specimens over three months. Results point out to the importance of using shelters to provide protection to sea urchins, and validated the efficiency of the calcein tagging protocol for in situ monitoring. Sea urchins' test diameter growth during the experiment was estimated to be 0.470 mm month−1 (SD = 0.181).

Paracentrotus lividus is a sea urchin widely distributed throughout Mediterranean basin and Atlantic coast, highly appreciated for its gonads. It is broadly distributed along the Portuguese coast and its exploitation has potential to grow. Nevertheless, fluctuations on nutritional composition and sensory traits of P. lividus according to each habitat and seasonality are still little understood. Stable isotopes analysis has been recognised as a powerful tool for exploring environmental-ecological-biological processes in aquatic systems. It is also useful to give indications on how to improve available diets for the aquaculture of this species, contributing to a sustainable rearing. Herein, such technique was used to assess temporal and spatial differences in isotopic composition of P. lividus' gonads and intestines and to evaluate its application as a management tool for the identification of the most suitable locations and periods of the year to collect organisms with high quality gonads. Sampling campaigns were carried out between 2019 and 2020 in five rocky shores along the Portuguese coast (Viana do Castelo, Figueira da Foz, Peniche, Sines and Guia). Three rock pools were selected in each shore, and five specimens were collected per pool. The gonadosomatic index (GSI, %) was calculated and carbon and nitrogen elemental and isotopic composition were determined in gonads and intestine using isotope ratio mass spectrometry. Significant spatial and temporal fluctuations were registered among urchins collected along Portuguese coast. Such variations may be associated with latitudinal gradients along the coast and variations of environmental and ecological conditions within each area, especially those affecting algal biomass, on which urchins primarily feed. More research must be pursued to maximise the use of stable isotopes analysis as a management tool for supporting sustainable exploitation of natural stocks or even to contribute to nutritional studies with new diets for sea urchin production that consider the feeding of these animals in the wild.

This dataset is based on the Project "Marine biodiversity information and monitoring systems in the Southwest Alentejo and Costa Vicentina Classified Areas (MARSW)". It presents occurrence data (5120 records) of the marine organisms observed in different location of the Southwest Alentejo and Costa Vicentina Natural Park from October 2018 to September 2020.

Understanding large-scale spatial and temporal patterns of marine populations is a central goal in ecology, which has received renewed attention under climate change. However, few studies explore the large-scale dynamics of populations using standardized protocols and during the same time frames. We studied the phenology and intensity of reproduction and recruitment for the intertidal stalked barnacle Pollicipes pollicipes over an European scale and described their potential linkages with environmental variables. This species supports profitable fisheries in the Iberian Peninsula (Spain and Portugal). In Brittany (France), we had observed a significant lower reproductive effort (long non-breeding season, short breeding period in summer) and low values of recruitment intensity. This pattern may be related to the fact that Brittany corresponds to the northern limit of the distribution of this species in continental Europe. On the Iberian Peninsula, the most different region was Galicia (Spain), with Asturias (Spain) and SW Portugal being more similar. In Galicia, we have observed a contradictory pattern characterized by the absence of a non-breeding period and by a shorter recruitment season than observed in other Iberian regions. Our results suggest that air temperature, SST and chlorophyll-a might be related to the variability in reproduction and recruitment patterns of P. pollicipes . Moreover, spring and early summer upwelling in SW Portugal and Galicia might be inhibiting recruitment in this period. At the northern limit, the expected increase in performance under climate change might facilitate the recovery of populations after exploitation, increasing the resilience of the resource to fishing pressure.

The stalked barnacle Pollicipes pollicipes is an abundant species on the very exposed rocky shore habitats of the Spanish and Portuguese coasts, constituting also an important economical resource, as a seafood item with high commercial value. Twenty-four elements were measured by untargeted total reflection X-ray fluorescence spectroscopy (TXRF) in the edible peduncle of stalked barnacles sampled in six sites along the Portuguese western coast, comprising a total of 90 individuals. The elemental profile of 90 individuals originated from several geographical sites (N = 15 per site), were analysed using several chemometric multivariate approaches (variable in importance partial least square discriminant analysis (VIP-PLS-DA), stepwise linear discriminant analysis (S-LDA), linear discriminant analysis (LDA), random forests (RF) and canonical analysis of principal components (CAP)), to evaluate the ability of each approach to trace the geographical origin of the animals collected. As a suspension feeder, this species introduces a high degree of background noise, leading to a comparatively lower classification of the chemometric approaches based on the complete elemental profile of the peduncle (canonical analysis of principal components and linear discriminant analysis). The application of variable selection approaches such as the VIP-PLS-DA and S-LDA significantly increased the classification accuracy (77.8% and 84.4%, respectively) of the samples according to their harvesting area, while reducing the number of elements needed for this classification, and thus the background noise. Moreover, the selected elements are similar to those selected by other random and non-random approaches, reinforcing the reliability of this selection. This untargeted analytical procedure also allowed to depict the degree of risk, in terms of human consumption of these animals, highlighting the geographical areas where these delicacies presented lower values for critical elements compared to the standard thresholds for human consumption.

The sea urchin Paracentrotus lividus (Lamarck, 1816) (Echinodermata: Echinoidea) is an important economic resource in Europe, but intense harvesting has led to the collapse of several natural populations. Echinoculture, associated with restocking and stock enhancement practices, is an alternative to this problem. In these procedures, reliable individual identification through tagging is a valuable source of information. However, very few studies address the effect of tagging methods on P. lividus and the tagging of marine invertebrates still presents several challenges: decreased growth, high mortality rates and low tag retention rates. Under laboratory conditions, the present study evaluated the effectiveness of three tagging methods (passive integrated transponders [PIT-tags], coded wire tags [CWTs] and calcein) on wild P. lividus for 60 days in terms of total wet weight, total weight gain (mg ind.−1 day−1), survival and tag retention. The final total wet weight was significantly higher in the untagged (control) group than in the PIT-tagged group. Survival rate was 100% for the PIT-tag, calcein and control groups, and 97% for the CWT group. Tag retention differed significantly according to the tagging method: 100% in the calcein group, 76.7% in the PIT-tag group and 38.0% in the CWT group.

Sea urchin gonads are an economically valuable seafood item, considered a delicacy in many parts of the world. However, its consumption can either pose a food safety threat, as they accumulate potentially toxic elements from contaminated environments or promote the depletion of natural stocks due to the high demand. Knowing their harvesting location is therefore paramount to guarantee food safety and the conservation of natural stocks. In this study, the elemental fingerprints of sea urchin (Paracentrotus lividus) gonads collected in several locations along the Portuguese coast, in 2020 and 2021, were used to assess the levels of some potentially toxic elements (i.e., As, Cu, Pb and Zn) and to trace the harvesting location of this marine resource. P. lividus gonads presented mean levels of As, Cu, Pb and Zn above the thresholds recommended for human consumption (considering mollusks due to the absence of safety thresholds for echinoderms), in at least one of the sampling locations. The elemental fingerprints of gonads hold the potential to trace the harvesting location of P. lividus, even when it was used elemental fingerprints of different years to train and test the models.

In January 2020, a stakeholder workshop was organized as a knowledge sharing strategy among European stalked barnacle fisheries. Management of this fishery differs greatly among regions and ranges from less organized and governed at large scales (>100 km, coasts of SW Portugal and Brittany in France) to highly participatory systems which are co-managed at small spatial scales (10's km and less, Galicia and Asturias). Discussions revealed that poaching is ubiquitous, hard to eradicate, and adapts to all types of management. The stakeholders identified some key management initiatives in the fight against poaching: granting professional harvesters with exclusive access to the resource, increasing social capital among harvesters through tenure systems (e.g. Territorial Use Rights in Fisheries) that empower them as stewards of their resource and intensification of surveillance with the active participation of the harvesters. Furthermore, increased cooperation between fishers associations and regional fisheries authorities, improved legal frameworks, adoption of new technologies and the implementation of market-based solutions can also help coping with this systemic problem.

Numerical biophysical models are a standard methodology used to provide estimates of larval dispersal and population connectivity for marine species with a bi-phasic life cycle. However, confidence on biophysical models, tested by confronting model estimates with empirical evidence, is seldomly assessed. We compared time-series estimates of larval supply of the stalked barnaclePollicipes pollicipesto rocky shores in 3 regions around the Iberian Peninsula (Asturias, Galicia, SW Portugal) with recruitment observations made at monthly intervals for 2 yr. Supply estimates were made with the Regional Ocean Modelling system using several larval behaviour scenarios, while the number of recruits on the stalks of adult barnacles was used as a measure of recruitment intensity. Cross-correlation analysis showed that passive, surface-dwelling and ontogenetically migrating larval scenarios generally produced significant positive correlations at time lags of 0 to +2 mo at the regional level but not at sub-regional or site levels. None of the scenarios produced a substantially better fit than the others, and all 3 produced estimates of average realized dispersal (-73 to +63 km in the S/W and N/E directions) and larval retention (2.0 to 2.4%) that were numerically very similar. These estimates indicate high levels of connectivity, either during larval life or via steppingstone processes, within and between the 3 regions. Based on these estimates, we advocate that the management of theP. pollicipesfishery requires an interactive, polycentric governance system at transregional, regional and local scales, which will give the resource a higher possibility of persistence by diversifying the fishery’s management portfolio.

No litoral rochoso do Alentejo pode-se encontrar uma grande abundância e diversidade de organismos vivos. Algumas espécies que aí vivem são popularmente conhecidas e utilizadas para consumo humano, como é o caso do polvo, mexilhão, percebe e ouriço-do-mar, e de várias espécies de lapas, búzios e caranguejos. Outras, como as cracas ou diversas espécies de algas ou de anémonas-do-mar, não são normalmente consumidas desta forma na costa alentejana e são menos conhecidas, embora algumas sejam apreciadas como alimento noutros países ou regiões.

Understanding recruitment patterns of an exploited species is essential to predict changes in population dynamics and to improve its management and conservation. Temporal variability in recruitment of the edible stalked barnacle Pollicipes pollicipes was analyzed over a decade (consecutive annual recruitment seasons from 2007 to 2016) at a cape area located in the Canary-Iberia Current Upwelling System (Cape of Sines, Southwestern Portugal), in terms of (1) the timing and length of the main recruitment season and (2) the variation in monthly and annual recruitment intensity and its relationship with several oceanographic variables. A longer recruitment season was detected, corresponding to approximately 9-10 months (June through either March or April of the following year, as in 2012, 2015, and 2016) in recent years, while a shorter recruitment season was detected between 2007 and 2010 (< 5 months, September-January in 2007 and July-December in 2010). Mean annual recruitment from 2012 to 2016 was about four times higher (ca. 43 recruits adult(-1)) than in the first 5 yr of the 10-yr period (ca. 12 recruits adult(-1)). Correlation analyses between monthly recruitment and oceanographic variables revealed a significant positive correlation with sea surface temperature and a negative correlation with upwelling index. Results indicate a trend toward a longer recruitment season and a higher recruitment intensity in recent years (2012-2016), and a clear association between recruitment of P. pollicipes and both relaxation of upwelling and seawater warming.

The engagement of the fishers and other stakeholders in the management of the resources is considered the key ingredient for a good fishery governance. The stalked barnacle Pollicipes pollicipes can be considered the most important economic resource on rocky shores of northern Spain and continental Portugal. This species is highly prized as food and it is heavily exploited. The main objective of the present study was to evaluate the temporal variation in the perception of P. pollicipes fishers at Berlengas Nature Reserve (RNB, the first area in Portugal to be managed for this fishery, since 2000) regarding the state of the fishery and the state of the management, and the implementation of a co-management system applied to the harvesting of this resource at RNB. The fishers' perception was evaluated by individual and direct interviews to professional P. pollicipes fishers with license to harvest at RNB, performed in 2005, 2013 (past studies) and 2018 (present study). The perception of the fishers about the state of P. pollicipes revealed an overall negative tendency of this resource at RNB, as they considered that the amount and size of the barnacles had decreased over time, and the quality remained the same. Most fishers also considered that P. pollicipes are being overexploited at RNB. The state of the management was defined as acceptable, as a large majority of the fishers agreed with most of the management measures, except for the spatial closures. However, their sense of nonfulfillment was high regarding most management measures in practice. Finally, an increasing percentage of the fishers agreed with the implementation of a co-management system applied to barnacle harvesting at RNB. This management shift might bring benefits perceived by the fishers as a better state of the resource, a more sustainable fishery management and an increase of the economic value of the resource. (C) 2020 Elsevier B.V. All rights reserved.

27 Partitioning the effects of herbivory on the different life stages of primary producers is 28 key to understanding the population-wide consequences of herbivory. We assessed the 29 performance of microscopic (MiS<1 mm) juveniles, macroscopic (MaS) juveniles and 30 adult kelp (Laminaria ochroleuca) under contrasting herbivory regimes through a 31 herbivore exclusion field experiment. The abundance of MiS and the survival of MaS 32 decreased by 67% and 63%, respectively, when herbivorous fishes and sea urchins were 33 present. Blade growth (linear and area) of adult kelp displayed contrasting patterns 34 under herbivore pressure: a 60% increase and a 46% decrease, respectively. These 35 results indicate that while herbivory severely reduces juvenile survival, it induces 36 compensatory growth (measured as linear growth) in adult kelp. In summary, we have 37 here demonstrated how herbivory affects all sporophyte life stages of the kelp L. 38 ochroleuca. This is likely to have important implications for all situations where 39 historical patterns of herbivore presence and herbivory are changing, such as in many 40 temperate to tropical transition zones around the world. 41 42