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The deep-sea Caribbean lobster (Metanephrops binghami) and the Norway lobster (Nephrops norvegicus) are Nephropidae species of high commercial interest. Although the first one still remains unexploited, the second is overexploited in the Mediterranean Sea. For effective fisheries management, size at sexual maturity is an essential indicator to protect immature individuals from exploitation. The estimation of this indicator can, however, be biased due to the difficulty of differentiating juveniles from adults by their size structure due to the natural process of molting. This study aims to estimate the size at sexual maturity of M. binghami and N. norvegicus females by comparing the effectiveness of the morphometric method versus the macroscopic evaluation of gonad maturity. Samples of M. binghami were collected from the Colombian Caribbean Sea in August and December 2009, March and May 2010, and August 2020 to May 2021. Samples of N. norvegicus were collected from the northwestern Mediterranean Sea from 2019 to 2022. Similar sizes at sexual maturity were found for M. binghami between the morphometric approach (ranging from 28.6 to 33.9 mm cephalothorax length, CL) and the gonadal staging approach (31.4 mm CL). Conversely, for N. norvegicus, the morphometric approach yielded higher measurements (between 27.2 and 30.4 mm CL) than the gonadal approach (26.0 mm CL). This discrepancy might stem from the intense fishing overexploitation conditions of N. norvergicus, leading to a physiological adaptation that enables earlier gonadal maturation at faster rates than morphometric adaptation. Further research is required to elucidate these discrepancies and the effect of overexploitation on physiological (i.e., mature gonads) and functional maturity (i.e., capacity to brood eggs at a larger size)

The deep-water rose shrimp is a main resource for the GSA 6 bottom trawling fleet. In the last decade, landings have increased without a clear understanding of the causes. This study aims to analyze this trend, potentially related to changes in environmental conditions. Results showed an increase in the species' landings, which spread northwards along the GSA 6. GAM models detected a significant effect of location, time, and depth on the distribution of the deep-water rose shrimp, as did for temperature and salinity. Similar values between landings and LPUE were found throughout, suggesting no effects of fishing effort in time. ANOVA tests showed a significant increase of sea bottom temperature and salinity in time, which were correlated with increasing LPUE values. Then, the trend seems to be related to environmental changes rather than changes in fishing effort. Further research is needed to implement management plans that ensure the resource sustainability

The Norway lobster, Nephrops norvegicus, is one of the most valuable fishery resources in many coastal countries of the Mediterranean Sea and the northeastern Atlantic Ocean. In the Mediterranean Sea, several stocks are being overexploited, with ecological, economic, and social consequences. To perform an adequate stock assessment and provide guidance on maximum sustainable yield, reliable biological parameters of the species are required. Considering that biological parameters may change over time in overexploited populations, in the present study, we updated key biological parameters for the N. norvegicus stock of the northwestern Mediterranean Sea: size at which 50% (L50) of females were in reproductive condition, length–weight relationship, and individual size structure. Moreover, daily landings were combined with the spatial position of the vessels tracked by their Vessel Monitoring System (VMS), to obtain information on the geographical distribution and time series of Landings Per Unit Effort (LPUE), as well as total landings from 2008 to 2021. Our results suggest overexploitation of the resource, revealing a severe reduction in size at 50% maturity, an earlier spawning and brooding period, and a clear decrease of LPUE over time

To assess conservation efforts and follow the effects of anthropogenic pressures, it is crucial to monitor the ecological status of benthic habitats. Monitoring requires measurements that are made on-site, reproduced over a vast region, and capable of capturing their spatial evolution over time. This calls for the expensively efficient development of tools and protocols that deliver reliable, high-quality data. This article introduces the PLOME multiparametric benthic landers, a new tool and protocol for non-extractively assessing the status of fishes and benthic habitats. By combining independent and wirelessly connected benthic stations, AUVs, and USVs, PLOME creates a spatially adjustable, non-invasive, modular platform. Lander stations will be able to continuously deliver high-rate data while AUVs can provide comprehensive spatial measurements

N. norvegicus supports one of the most commercially-important fisheries in the Mediterranean, and there is considerable interest in developing non-invasive sampling stock assessment methods. Currently, stock assessments are conducted via trawling or by UnderWater TeleVision (UWTV) surveys with limited capacity to provide direct population data due to the burrowing behavior of the species. Here, we used acoustic telemetry to characterize the burrow emergence and movement patterns of N. norvegicus in relation to internal tides and inertial currents in deep-sea habitats of the northwestern Mediterranean. We deployed acoustic tags on 25 adults between May and June 2019, and collected up to 4 months of detection data from each tag. Tagged lobsters spent approximately 12% of their time in door-keeping (i.e., detections at burrow entrance with no displacements) but differences existed among the different behavioral rhythms identified. We observed that mixed day-night, tidal and inertial rhythms in field settings were similar to those observed in laboratory tests. The presence of mixed day-night and tidal periodicity poses the question of why N. norvegicus exhibits flexible responses to environmental cues other than photoperiod. It is possible that tidal regulation of locomotor activity could reduce energy expenditure in relation to hydrodynamic drag. Inertial periodicity occurs in animals with no clear burrowing-oriented activity (always present on the seabed). Possibly, inertial-related movements are the result of a disruption of the biological clock. Our results are discussed in the context of how burrow emergence rhythms may bias UWTV surveys and how novel in situ monitoring approaches address these biases

In the context of marine conservation, trawl fishing activity is the most important ecosystem stressor in demersal Mediterranean waters. Limited management measures in bottom trawling have caused deep-sea stocks of the iconic Norway lobster Nephrops norvegicus to decrease over the last decade. This crustacean acts as an umbrella species for co-existing megafauna. Here, we used non-invasive Remote Operated Vehicle (ROV) video-surveys to investigate the status of a pilot deep-sea no-take reserve implemented in the northwestern Mediterranean by quantifying demographic indicators of Norway lobsters and the co-existing benthic community, seafloor restoration, and the presence of marine litter. The results revealed that in the no-take reserve the Norway lobster stock showed higher abundance and biomass, and slightly larger body sizes than in the control area without fishing prohibition. Some taxa, such as the fishes Helicolenus dactylopterus and Trigla lyra and anemones of the family Cerianthidae, increased in abundance. We also observed that all trawling marks were smoothed and most of the seafloor was intact, clear indicators of the recovery of the muddy seafloor. The accumulation of marine debris and terrestrial vegetation was similar in the no-take reserve and the fished area. On the basis of the results of this study, we suggest that the use of no-take reserves might be an effective measure for recovering the Norway lobster stock, its co-existing megafauna community, and the surrounding demersal habitat. We also suggest that ROV video-survey might be a useful, and non-invasive method to monitor megafauna and seafloor status in protected deep-sea environments

La mayor parte de los stocks pesqueros demersales del mar Mediterráneo se encuentran en niveles de sobreexplotación (FAO, 2020; Osio et al., 2015) y presentan altos niveles de descartes (Blanco et al., 2022). [...]

One of the main drivers of marine ecosystem change is fishing activity, bottom trawling being the most intensive fishing practice affecting benthic ecosystems worldwide. In the western Mediterranean Sea, Norway lobster stocks present signs of overexploitation due to trawling pressure, as their biomass and abundance have decreased abruptly during the last few years. No-take fishery reserves, a type of marine protected area where fishing is prohibited, could be efficient management measures to recover Norway lobster overexploited populations and coexisting demersal megafauna. Adopting a BACI (before–after control–impact) approach, we performed experimental fishing surveys before and after 4 years of the implementation of a deep-sea no-take reserve in the northwestern Mediterranean. After 4 years of closure, the Norway lobster population increased in abundance, biomass, body size, and trophic level in the no-take reserve. Our approach also revealed an increase in Norway lobster biomass beyond its boundaries, suggesting a spillover effect. Other demersal fish species also increased in biomass and abundance in the no-take reserve. Based on the results of this study, we suggest that no-take reserves might be an effective measure for recovering the Norway lobster stock and some species present in the same habitat

The burrowing crustacean decapod Nephrops norvegicus is a significant species in European Atlantic and Mediterranean fisheries. Research over the decades has mainly focused on behavioral and physiological aspects related to the burrowing lifestyle, since animals can only be captured by trawls when engaged in emergence on the seabed. Here, we performed a global bibliographic survey of all the scientific literature retrieved in SCOPUS since 1965, and terminology maps were produced with the VOSviewer software to reveal established and emerging research areas. We produced three term-map plots: term clustering, term citation, and term year. The term clustering network showed three clusters: fishery performance, assessment, and management; biological cycles in growth, reproduction, and behavior; and finally, physiology and ecotoxicology, including food products. The term citation map showed that intense research is developed on ecotoxicology and fishery management. Finally, the term year map showed that the species was first studied in its morphological and physiological aspects and more recently in relation to fishery and as a food resource. Taken together, the results indicate scarce knowledge on how burrowing behavior and its environmental control can alter stock assessment, because of the poor use of current and advanced monitoring technologies

In the last decades, stock assessment surveys targeting the Norway lobster Nephrops norvegicus have been gradually moving from physical/extracting sampling (e.g., trawling surveys) towards video/imaging-based solutions such as UnderWater TeleVision (UWTV) surveys with towed sledges. However, both approaches still face operational challenges which may introduce bias when translating the basic data (individuals captured by trawling or burrow systems filmed by UWTV) to accurate densities. In the future, an ecosystem-based monitoring and assessment plan should: improve the currently used equation “1 burrow system ≈ 1 animal”; include activity rhythms in sampling; derive other ecological indicators (e.g., biodiversity); and increase automa-tion in image/data processing. This requires deploying intelligent monitoring networks consist-ing of stationary and mobile platforms with distinct focus and capabilities, while integrating novel sampling methodologies (i.e., eDNA/eRNA; opto-acoustic mapping, etc.). In parallel, pow-erful Artificial Intelligence algorithms should be integrated to streamline data analysis and assist the extraction of ecological information in the form of hierarchically computed indicators, from animal counts and size all the way to ecosystem functioning. This rationale was detailed in a 2022 publication led by ICM-CSIC (Aguzzi et al., 2022), with the participation of several WGNEPS members

Deep-sea fishing has been carried out on an industrial scale since the 1950s, and this has had a variety of effects on the environment and its biota. Most benthic species experience a decline in abundance or a constant decline in abundance as a result of direct disturbance of the seafloor, such as its plowing and scraping by hauled nets, with overall impacts on regional biodiversity [1]. Sediment has lost some of its biogenic habitat complexity, and sessile epifauna-provided microhabitat has been destroyed or disrupted [2] and marine protected areas (MPAs) have been widely implemented to address this decline. Marine fish mobility, which is crucial for ecosystem function and is increasingly being researched with acoustic telemetry, has an impact on how well no-take MPAs (i.e., marine reserves) work in terms of protecting and repopulating fish populations [3], [4] Therefore, it is necessary to continuously monitor periodic changes in commercially exploited deep-sea ecosystems in order to gather baseline information, give accurate environmental impact assessments, and derive sound biological indicators for restoration. Using a fixed acoustic ultra-short baseline (USBL) receiver on benthic lander and miniature bidirectional acoustic tags [5], we address three key questions: How far can fish move? Does connectivity exist between adjacent MPAs? Does existing MPA size match the spatial scale of fish movements?

The dynamics of phytoplankton biomass and community composition is important for the functioning of marine ecosystems and ocean biogeochemical cycles. However, there is a shortage of studies addressing the interannual seasonal patterns of phytoplankton community assembly due to sampling limitations. Here we study the seasonal dynamics of eight major phytoplankton groups over a 12 year period (2006 to 2018) using a time-series of taxonomic composition from the Blanes Bay Microbial Observatory (BBMO) in the North Western Mediterranean Sea: dinoflagellates, diatoms, coccolithophores, Prochlorococcus, Synechococcus, picoeukaryotes, nanoeukaryotes, and photosynthetic nanoflagellates. We combine the analysis of biotic factors (primary production, phytoplankton taxa, cell abundance, cell size, chlorophyll-a concentration, and phytoplankton biomass) and abiotic factors (nutrients, temperature, and irradiance) to provide a coherent picture of the observed seasonal patterns of phytoplankton community assembly. The BBMO ecosystem is seasonally heterogeneous in community composition, displaying large fluctuating alternations in phytoplankton group dominance throughout the year. The seasonal succession of phytoplankton groups tends to repeat itself every year in a regular fashion, being the seasonal variability of the phytoplankton groups larger than their interannual variability. We compute -diversity, a measure of the effective richness of phytoplankton groups. The seasonality of -diversity shows that it is lowest during winter and highest during summer. We compute temporal -diversity, a measure of compositional heterogeneity of the phytoplankton community. The data show a sinusoidal behavior of -diversity as a function of the temporal distance between samples, with a period of one year. We use the mirror index (1 - -diversity) at a temporal distance of one month to compute the phytoplankton group turnover. The seasonality of turnover shows that it is highest during spring and

The Norway lobster, Nephrops norvegicus, supports a key European fishery. Stock assessments for this species are mostly based on trawling and UnderWater TeleVision (UWTV) surveys. However, N. norvegicus are burrowing organisms and these survey methods are unable to sample or observe individuals in their burrows. To account for this, UWTV surveys generally assume that “1 burrow system = 1 animal”, due to the territorial behavior of N. norvegicus. Nevertheless, this assumption still requires in-situ validation. Here, we outline how to improve the accuracy of current stock assessments for N. norvegicus with novel ecological monitoring technologies, including: robotic fixed and mobile camera-platforms, telemetry, environmental DNA (eDNA), and Artificial Intelligence (AI). First, we outline the present status and threat for overexploitation in N. norvegicus stocks. Then, we discuss how the burrowing behavior of N. norvegicus biases current stock assessment methods. We propose that state-of-the-art stationary and mobile robotic platforms endowed with innovative sensors and complemented with AI tools could be used to count both animals and burrows systems in-situ, as well as to provide key insights into burrowing behavior. Next, we illustrate how multiparametric monitoring can be incorporated into assessments of physiology and burrowing behavior. Finally, we develop a flowchart for the appropriate treatment of multiparametric biological and environmental data required to improve current stock assessment methods.

Our understanding of marine ecosystem functioning and processes relies on adequate spatio-temporal multiparametric monitoring procedures. Over the next 3 years, the Project PLOME (Platforms for Long-lasting Observation of Marine Ecosystems) will implement a spatially adaptive and autonomous network of easy-to-use benthic landers with dockable Autonomous Underwater Vehicles (AUVs)ñ This network will be used to intelligently video-monitor and map marine ecosystems and their environment from coastal to deep-sea areas. All platforms will be connected via acoustic or optical communication and will operate over periods of weeks to months with real-time supervision. Stations will provide continuous and intensive temporal observations, while dockable AUVs (with battery recharge and data downloading capability) will provide intensive measurements at various spatial scales, using intelligent and adaptive trajectories to explore surrounding areas. Biological, geochemical and oceanographic data will be generated by an array of sensors including acoustic receivers and cameras. Images will be processed in real-time for species classification and tracking, using advanced data analysis and Deep Learning techniques. Metadata will be communicated between landers and AUVs and transmitted opportunistically whenever an Unmanned Surface Vehicle (USV) connects the platform via aerial communications (i.e. GSM and satellite communications, depending on form distance to shore). The unattended operation will also be possible with an innovation of pop-up buoys that will allow data transfer to the surface from landers and UAVs to be relayed once the pop-up buoys reach the surface. Complex ecological indicators for ecosystem management will be computed from the collected data, by applying advanced computer vision techniques to classify, count and size individuals in video images and to generate multimodal maps of the seabed. A pipeline for automated data treatment will be tailored for multiparam

The Norway lobster, Nephrops norvegicus, supports a key European fishery. Stock assessments for this species are mostly based on trawling and UnderWater TeleVision (UWTV) surveys. However, N. norvegicus are burrowing organisms and these survey methods are unable to sample or observe individuals in their burrows. To account for this, UWTV surveys generally assume that “1 burrow system = 1 animal”, due to the territorial behavior of N. norvegicus. Nevertheless, this assumption still requires in-situ validation. Here, we outline how to improve the accuracy of current stock assessments for N. norvegicus with novel ecological monitoring technologies, including: robotic fixed and mobile camera-platforms, telemetry, environmental DNA (eDNA), and Artificial Intelligence (AI). First, we outline the present status and threat for overexploitation in N. norvegicus stocks. Then, we discuss how the burrowing behavior of N. norvegicus biases current stock assessment methods. We propose that state-of-the-art stationary and mobile robotic platforms endowed with innovative sensors and complemented with AI tools could be used to count both animals and burrows systems in-situ, as well as to provide key insights into burrowing behavior. Next, we illustrate how multiparametric monitoring can be incorporated into assessments of physiology and burrowing behavior. Finally, we develop a flowchart for the appropriate treatment of multiparametric biological and environmental data required to improve current stock assessment methods

The trawling fishing activity constitutes today half of all EU fisheries and its use is one of the main drivers of ecosystem degradation of demersal ecosystems (Puig et al., 2012). Trawling removes the sediments and endangers demersal fragile sessile organisms, being long-lived species replaced by short-lived ones. In the Mediterranean, many demersal stocks are overexploited, reducing the economic benefits of fisheries and the ecosystem services associated with cultural aspects of iconic species. Given this situation, ecological networks of Marine Protected Areas (MPAs) as no-take reserves, are being created to preserve Nephrops norvegicus stocks, according to the principles of habitat connectivity, with appropriate scales of geographic proximity for larval dispersal (Vigo et al. 2021). Although the primary aim of MPAs is the conservation of Nephrops stocks, they also allow the recovering of the associated sessile fauna, that trapping the sediment accelerates the whole habitat restoration process. The repopulation of soft bodied cold water corals by badminton technique is the main goal of the LIFE-ECOREST Project. [...]

Decapod crustaceans are a diverse group englobing several species of commercial and ecological interest. In the Mediterranean Sea, decapod crustacean fisheries are among the most profitable, although in many cases their early life stages are poorly known. In this study, we tackle the composition and diversity patterns of the decapod larval communities along the eastern Spanish Mediterranean coast. Zooplankton sampling was carried out in surface waters at 101 stations from July 20th to August 31st 2016, over bottom depths between 90 and 1840 m. All shrimp larvae were identified to the lowest possible taxonomical level, and larvae from Anomura, Achelata and Brachyura were left at infraorder level. No larvae of Astacidea or Polychelida were found. The total zooplankton volume was estimated. A total of 20,022 decapod crustacean larvae were identified, focusing on shrimp taxa (suborder Dendrobranchiata and infraorder Caridea). Both zooplankton volume and decapod larval density values were higher in the northern part of the studied area, cut by deep submarine canyons. After assessing the diversity parameters of the decapod larval community, we present the summer mesoscale larval distribution of several species of commercial interest such as the caramote prawn (Penaeus kerathurus) or the deep-water rose shrimp (Parapenaeus longirostris). The northern submarine canyons are dominated by the presence of Penaeoidea, being the deep-sea shrimp Aristeus antennatus the dominant species in the community in this area, while the Sergestoidea are more abundant in the southern zone. This is the largest-scale study on decapod larvae mesoscale distribution in the Mediterranean Sea

[EN] The oceans cover about 71% of the Earth’s surface and contain about 97% of the living space on the planet and somewhere between 500000 and 10 million different species. Oceans provide humans with natural benefits such as seafood provisioning, carbon storage and climate regulation –the so-called ecosystems services. However, despite their paramount importance for the maintenance of life and human wellbeing, oceanic systems are among the most complex, poorly understood and impacted biomes. […], [ES] Los océanos cubren aproximadamente el 71% de la superficie de la Tierra, representan el 97% del espacio habitable del planeta, y alojan entre 500.000 y 10 millones de especies marinas. Los océanos son también una incalculable fuente de beneficios para los humanos, ofreciéndonos múltiples servicios ecosistémicos: constituyen una de las principales fuentes de alimentos y juegan un papel fundamental en el ciclo del carbono y en la regulación del clima. A pesar de su importancia en el mantenimiento de la vida y el bienestar humano, los océanos se encuentran entre los biomas de la Tierra más complejos, desconocidos e impactados por la presión del clima y las actividades humanas. […], [CAT] Els oceans cobreixen aproximadament el 71% de la superfície de la Terra, representen el 97% de l’espai habitable del planeta, i allotgen entre 500.000 i 10 milions d’espècies marines. Els oceans són també una incalculable font de beneficis per als humans, oferint-nos múltiples serveis ecosistèmics: constitueixen una de les principals fonts d’aliments i juguen un paper fonamental en el cicle del carboni i en la regulació del clima. Malgrat la seva importància en el manteniment de la vida i el benestar humà, els oceans es troben entre els biomes de la Terra més complexos, desconeguts i impactats per la pressió del clima i les activitats humanes. […]

[EN] The oceans provide important ecosystem services, and protein provisioning is one of the main benefits for humanity. The millenarian Mediterranean fishing activity today accounts for almost half of all the fisheries in the EU, and the use of high-impact fishing methods has made this human activity one of the main drivers of ecosystem degradation, especially in demersal and benthic environments (Puig et al. 2012). Bottom otter gear (hereafter trawling) causes the removal of sediments and endangers demersal living resources and their ecosystems, with fragile epi-faunal species being replaced by mobile scavengers or predators and long-lived species being replaced by short-lived species. In the Mediterranean Sea, many commercial demersal populations are being overexploited, reducing the economic benefits of fisheries and the ecosystem services associated with cultural aspects of iconic species. […], [ES] Los océanos proporcionan importantes servicios ecosistémicos, siendo el suministro de proteínas uno de los principales beneficios para la humanidad. La actividad pesquera del Mediterráneo constituye hoy en día casi la mitad de todas las pesquerías de la UE y el uso de métodos de pesca de alto impacto ha convertido a esta actividad en una de las principales impulsoras de la degradación de los ecosistemas de aguas profundas (Puig et al. 2012). El arte de pesca de arrastre provoca la eliminación de sedimentos y pone en peligro los recursos vivos demersales y sus ecosistemas, y las especies de epi-fauna frágiles son reemplazadas por especies carroñeras o depredadoras y las especies longevas son reemplazadas por especies de vida corta. En el mar Mediterráneo, muchas poblaciones de especies comerciales que habitan hábitats demersales están siendo sobreexplotadas, lo que reduce los beneficios económicos de la pesca y los servicios ecosistémicos asociados a los aspectos culturales de algunas especies consideradas icónicas. […], [CAT] Els oceans proporcionen importants serveis ecosistèmics, i és el subministrament de proteïnes un dels principals beneficis per a la humanitat. L’activitat pesquera mil·lenària del Mediterrani constitueix avui en dia gairebé la meitat de totes les pesqueres de la UE i la utilització de mètodes de pesca d’alt impacte ha convertit aquesta activitat humana en un dels principals impulsors de la degradació dels ecosistemes, especialment en entorns bentònics (Puig et al. 2012). L’art de pesca d’arrossegament provoca l’eliminació de sediments i posa en perill els recursos vius demersals i els seus ecosistemes, i les espècies d’epi-fauna fràgils són substituïdes per carronyaires o depredadors mòbils i les espècies de llarga vida són substituïdes per espècies de vida curta. A la mar Mediterrània, moltes poblacions demersals comercials estan essent sobreexplotades, el que redueix per a les espècies icòniques, els beneficis econòmics de la pesca i els serveis ecosistèmics associats amb els aspectes culturals. […]