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More than half of the Mediterranean sharks and rays are threatened by fishing exploitation. However, population assessments are limited by the scarcity of specific data on fishing catches. In this study, we assessed temporal trends of the indicators developed within the European Marine Strategy Framework Directive over the last two decades in order to assess the conservation status of demersal sharks and batoids in the Balearic Islands, which represent an important fraction of the bycatch of bottom trawling in this area. On the basis of a georeferenced, fishery-independent dataset of 19 species of elasmobranchs, we analyzed 20 year time series (2002–2021) of nine indicators regarding area distribution, population size, population status, and community structure. Between 30% and 50% of the elasmobranch species and functional groups showed increasing trends in distribution area and population size. This was especially true for batoids, whereas the distribution area and population size of most sharks remained stable over the study period. The remaining indicators showed stability or, in some cases, variable trends. Only in one case did we find a negative trend sustained all along the time series (i.e., the proportion of R. radula large individuals in relation to the reference period). Overall, our results suggest that the populations of elasmobranchs from the Balearic Islands show stable or recovery trends, mainly in terms of distribution area and density. However, it remains elusive whether this community can recover to the levels of more than half a century ago, before the development of the bottom trawl fishery, or whether this apparent current steady state should be interpreted as a new equilibrium.

Fisheries management requires the best scientific knowledge on the exploitation and conservation status of stocks. This is challenging for by-catch species, for which necessary data for their assessment is more limited than for target ones. That is the case for the thornback ray, Raja clavata, in the Balearic Islands (western Mediterranean), whose exploitation and conservation status are addressed here for the first time, in an integrative approach, by using innovative assessment methods and genetic diversity analysis. The time series of fishing landings from 1964 and MEDITS trawl survey data from 2004 were used to apply CMSY++ and Bayesian state-space Schaefer production models. We also estimated the genetic diversity of the Cytochrome C Oxidase subunit I mitochondrial gene from 31 individuals collected during MEDITS surveys. The species showed overexploitation with a current fishing mortality (F) below that producing maximum sustainable yield (FMSY), but with a current stock biomass (B) lower than BMSY. Despite the fact that the exploitation status is stable or even has improved in the last decades, the overexploitation period since the late 1970s seems to have reduced levels of genetic diversity, below those of related species and other populations of R. clavata. This low genetic diversity may entail the loss of adaptive potential, making the species more vulnerable to fishing and the current climate change., This study has been cofunded by the EU through the European Maritime and Fisheries Fund (EMFF) within the Data Collection National Program, management and use of data from fisheries sector; also by the Ministry of European Funds, University and Culture of the Baleric Islands through the grants for the training of research personnel 2021 (F. Ferragut-Perelló) and the Post-doctoral contract (S. Ramírez-Amaro) of the Vicenç Mut Estabilitat program co-financed by the Government of the Balearic Islands and the European Social Fund. N. Petit-Marty is supported by MSCA-PF FishAdapt 101066785. This research was partly funded by the European Union’s Horizon 2020 Research and Innovation Program (H2020-BG-10-2020-2), grant number No. 101000302—EcoScope (Ecocentric management for sustainable fisheries and healthy marine ecosystems). The funders had no role in study design, data collection and analysis, decision to publish or preparation of the manuscript.

The poorly known sponge species Axinella vellerea (Topsent, 1904), Acarnus levii (Vacelet, 1960) and Haliclona poecillastroides (Vacelet, 1969) are reported from bottom-trawl samples off the Balearic Islands, Western Mediterranean. A re-description is provided for all three species and the Folmer fragment of cytochrome oxidase subunit I (COI) obtained for A. levii and H. poecillastroides. This is the second report of A. vellerea in the Mediterranean, the first time that A. levii is reported outside Corsica and the first time that H. poecillastroides is documented outside the Gulf of Lion, France. The systematic allocation of A. levii and H. poecillastroides is discussed based on a COI phylogenetic analysis and morphology. The poorly understood phylogeny of the Haplosclerida does not permit us to find a proper allocation for H. poecillastroides, although its current position in the genus Haliclona or the family Chalinidae is not defensible. On the other hand, A. levii currently fits best in the family Microcionidae, and seems related to some Clathria species with mixed features between Clathria and Acarnus. Considering that the species of the genus Acarnus shares a strong synapomorphy (the possession of Cladotylotes), it is plausible for all Acarnus species to be Microcionids. We conclude that H. poecillastroides needs to be reallocated to a new genus: Xestospongia poecillastroides comb. nov. (Petrosiidae). However, a reallocation of A. levii is not advisable for the moment, as this would imply major systematic changes such as the reallocation of the whole genus Acarnus to Microcionidae, and the redescription of Microcionidae and Acarnidae., Sí

Mackerel is an important commercial pelagic species present in the western and eastern North Atlantic. The Northeast Atlantic Mackerel (NEAM) stock has its southernmost spawning area mainly located western Iberian Peninsula and southern Biscay. This species performs extensive annual migrations. The present study is focused on the distribution of this species along the Cantabrian Sea, an essential area of the South Spawning Component (SSC), and the environmental drivers that can affect its migration phenology. We have used data from Vessel Monitoring System and Logbooks of the hand line fishery to estimate the catch per unit of effort (CPUE) as a proxy of its distribution and abundance. CPUEs data of fisheries targeting NEAM provided us with a tool to discriminate the most important predictors for both its prespawning and the postspawning behavior. Among the drivers that can affect mackerel migration, we have analyzed wind speed and direction, temperature at surface (SST) and at 200 m depth, chlorophyll a, mixed layer depth, upwelling intensity, and the most representative geographical variables: depth, slope of the seafloor, and distance to coast. We used generalize additive models to highlight the predictors most closely related to the phenology of the species and to shape the spatial–temporal abundance of NEAM in the southern Bay of Biscay waters. Temperature and wind speed and direction are the most important factors that affect prespawning and postspawning migration of NEAM SSC and shape its niche tracking leading to a gradual advance of the spawning season. Postprint 2,044

A new approach to recruitment overfishing diagnosis is presented. We hypothesize that condition of recruits should increase when recruitment failures are caused by fishing activity. This would be a consequence of the increase in trophic resource availability, because the population is smaller than that which the ecosystem could support. Temporal series of hake recruit condition were calculated from MEDITS survey data collected in Mediterranean geographical sub-areas (GSAs) 1, 6, 17 and 19 from 1994 to 2015. Multiple linear regressions were used to analyse the relationship between mean annual condition and abundance of recruits and climatic indices in each GSA. Significant correlations were only detected in GSA 6, where 69% of condition variability was explained by the negative correlation with recruit abundance, and with two climatic indices, the Western Mediterranean Oscillation and the standardized air temperature anomaly at surface from the Gulf of Lions. Despite the differences in recruit abundance among GSAs, their mean annual condition oscillated around the same basal value during most of the time series, pointing to density-dependent mortality rates as an important mechanism stabilizing hake recruitment to levels close to the carrying capacity when populations do not suffer recruitment overfishing. This pattern changed when the decreasing recruit abundance trend drove GSA 6 condition values persistently above those of the rest of the GSAs. According to our hypothesis, hake in GSA 6 is in recruitment overfishing., Este trabajo presenta una nueva aproximación al diagnóstico de la sobrepesca de reclutamiento. Nuestra hipótesis consiste en que la condición de los reclutas debe aumentar cuando suceden fallos en el reclutamiento debidos a la actividad pesquera. Esto sería una consecuencia del incremento en la disponibilidad de recursos tróficos debido a que la población es más reducida que la que el ecosistema podría soportar. Se calcularon series temporales de condición de reclutas de merluza a partir de datos recogidos en las campañas MEDITS en las sub-áreas geográficas (GSAs) 1, 6, 17 y 19 entre los años 1994 y 2015. Se utilizó la regresión lineal múltiple para analizar la relación entre la condición media anual y la abundancia de reclutas e índices climáticos en cada GSA. Solo se detectaron correlaciones significativas en la GSA 6, dónde el 69% de la variabilidad en la condición se explica por la correlación negativa con la abundancia de reclutas, y con dos índices climáticos, la Oscilación del Mediterráneo Occidental y la anomalía estandarizada de la temperatura del aire en superficie en el Golfo de León. A pesar de las diferencias en la abundancia de reclutas entre GSAs, su condición anual media osciló alrededor de un mismo valor basal durante la mayor parte de la serie temporal, sugiriendo que las tasas de mortalidad denso-dependiente son un mecanismo importante para la estabilización del reclutamiento de merluza en niveles próximos a la capacidad de carga cuando las poblaciones no sufren sobrepesca de reclutamiento. Este patrón cambió cuando la tendencia decreciente de la abundancia de reclutas elevó los valores de condición en la GSA 6 por encima de los del resto de GSAs de forma persistente. De acuerdo con nuestra hipótesis, la merluza de la GSA 6 se encuentra en sobrepesca de reclutamiento.

The MEDITS programme started in 1994 in the Mediterranean with the cooperation among research institutes from four countries: France, Greece, Italy and Spain. Over the years, until the advent of the European framework for the collection and management of fisheries data (the Data Collection Framework, DCF), new partners from Slovenia, Croatia, Albania, Montenegro, Malta and Cyprus joined MEDITS. The FAO regional projects facilitated the cooperation with non-European countries. MEDITS applies a common sampling protocol and methodology for sample collection, data storage and data quality checks (RoME routines). For many years, MEDITS represented the most important data source supporting the evaluation of demersal resources by means of population and community indicators, assessment and simulation models based on fishery-independent data. With the consolidation of the DCF, MEDITS routinely provides abundance indices of target species for tuning stock assessment models of intermediate complexity. Over the years, the survey scope has broadened from the population of demersal species to their fish community and ecosystems, and it has faced new challenges, such as the identification of essential fish habitats, providing new scientific insights linked to the Marine Strategy Framework Directive (e.g. biodiversity, trophic webs, allochthonous species and marine macro-litter evaluations) and to the ecosystem approach to fishery and marine spatial planning. El programa MEDITS comenzó en 1994 en el Mediterráneo, con la cooperación entre institutos de investigación de cuatro países: Francia, Grecia, Italia, España. A lo largo del tiempo, y con la puesta en marcha del programa europeo para la recopilación y gestión de datos pesqueros (Data Collection Framework, DCF), se unieron nuevos socios como Eslovenia, Croacia, Albania, Montenegro, Malta y Chipre. Los proyectos regionales de FAO han facilitado la cooperación con países no europeos. MEDITS aplica un protocolo y una metodología de muestreo comunes, que abarca desde la recolección de muestras hasta el almacenamiento de datos y los controles de calidad de los mismos (programa RoME). Durante muchos años, MEDITS ha sido la fuente de datos más importante para la evaluación de los recursos demersales, mediante indicadores de población y comunidad y modelos de evaluación y simulación, basados en datos independientes de la pesca. Con la consolidación del DCF, MEDITS proporciona rutinariamente índices de abundancia de especies objetivo, que se usan para ajustar modelos de evaluación de stocks. A lo largo del tiempo, los objetivos de las campañas se han ampliado desde las poblaciones demersales a sus comunidades y ecosistemas, afrontando nuevos desafíos, como la identificación de hábitats esenciales para los peces, y proporcionando nuevos planteamientos científicos vinculados a la Directiva Marco sobre la Estrategia Marina (p.ej. biodiversidad, redes tróficas, especies alóctonas y evaluaciones de basura marina), así como la aproximación ecosistémica a las pesquerías y la Planificación Espacial Marina.

The first record of the ophiuroid family Ophiohelidae from the Mediterranean Sea is reported. It consists of the description of the new record of Ophiomyces grandis from the Mallorca Channel seamounts in the Balearic Islands, western Mediterranean, where it shows high abundances. We present both the morphological description of the individuals collected and, for the first time, the cytochrome oxidase subunit I (COI) sequence of this species. The morphological traits of our specimens match the available descriptions of O. grandis. On the other hand, molecular analyses show a large genetic distance between O. grandis and Ophiomyces delata, the two species being very similar morphologically. Despite the high abundances of O. grandis reported here, previous surveys in the Mallorca Channel seamounts using ROV did not detect it, emphasizing the importance of beam trawl sampling to improving the biodiversity description of these geomorphological sea bottom features., Sí

In marine ecosystems, where variability in the type and availability of food resources is a common property, species must adjust their feeding behaviour in order to fulfil their energetic needs within the requirements of ontogeny. These variations in the quality and quantity of food supply are crucial for the nutritional status of individuals. We have approached these relationships by analyzing the isotopic composition and somatic body condition of European hake within three areas in the western Mediterranean: the waters off the Ebro river Delta and the north-eastern coast of the Iberian Peninsula, both in the Spanish mainland, and the Balearic Islands. These locations have contrasting oceanographic conditions and degrees of productivity. Results reveal important ontogenetic and spatial differences in the isotopic composition and body condition of recruits and juveniles, as well as a distinct trophic structure and pathways between areas. Isotopic signatures revealed differences between the waters off the mainland and the Balearic Islands, with an overlap in the isotopic niche of recruits and juveniles in the mainland waters that contrasted with a clear separation in the Islands. The linkage between trophic ecology and somatic body condition revealed that this relationship cannot be as straightforward as expected, highlighting the importance of ecological processes such as competition for food resources. This study reveals the short scale spatial complexity in the trophic ecology of European hake and its relationship with the nutritional status. Acknowledging such complexity is of high importance towards the implementation of integrative management approaches of marine living resources.

Since the 1990s, most currently assessed Mediterranean nekto‐benthic stocks have been exploited above maximum sustainable yield and have declined. This study explores the co‐occurrence of essential fish habitats for the most important nekto‐benthic resources exploited by bottom‐trawl fisheries in the western Mediterranean and areas of importance for nekto‐benthic communities. Fishery‐independent data obtained from Mediterranean scientific bottom‐trawl surveys were used to identify persistent hotspots of recruitment for the most important nekto‐benthic species around the Iberian Peninsula and the Balearic Islands between 2002 and 2016, as an indicator of their essential fish habitats. Likewise, hotspots of nekto‐benthic community diversity and density were also determined, as an estimate of key areas for nekto‐benthic communities. Areas of overlap of persistent hotspots of recruitment and of community species richness and density were mainly found on the deep shelf and the upper slope (100–200 m and 200–500 m deep respectively). These overlapping areas could be of particular interest in the development of fishery management plans aiming to implement an ecosystem approach to fisheries. Protection, through temporary or permanent closures, of the overlapping areas identified would contribute to improving both the sustainable exploitation of the main target species of bottom‐trawl fisheries and the conservation of nekto‐benthic communities.

The high discards rates of non-commercial benthic species is one of the main problems of the Mediterranean bottom trawl fishery developed on the continental shelf. The present work analyzes data from 22 bottom trawls, carried out in parallel by two commercial trawlers between 70 and 90 m depth on maërl beds off eastern Menorca (Balearic Islands). One vessel used an experimental trawl gear (EXP) equipped with a lighter and smaller groundrope in the mouth of the net, leaving a gap without net between the main groundrope and the secondary one. The other vessel used a trawl gear traditionally used by the fleet operating in the area (TRA), without that modification. Catches, discards and commercial yields between both gears were compared. Discarded biomass of non-commercial benthic species with EXP was reduced by half when compared to TRA, particularly for rhodoliths (54%) and ascidians (51%). The reduction of discarded rhodoliths is especially relevant in the Balearic Islands where sensitive habitats, such as maërl beds, are an important part of the benthic communities. The modification of the net, at the same time, does not imply a reduction of yields of commercial captures and can easily be implemented in any bottom trawl net. It is concluded that this could be an appropriate and plausible technical measure to improve the ecological efficiency and the sustainability of the Mediterranean bottom trawl, SI

Independence of science and best available science are fundamental pillars of the UN-FAO code of conduct for responsible fisheries and are also applied to the European Union (EU) Common Fishery Policy (CFP), with the overarching objective being the sustainable exploitation of the fisheries resources. CFP is developed by DG MARE, the department of the European Commission responsible for EU policy on maritime affairs and fisheries, which has the Scientific, Technical and Economic Committee for Fisheries (STECF) as consultant body. In the Mediterranean and Black Sea, the General Fisheries Commission for the Mediterranean (FAO-GFCM), with its own Scientific Advisory Committee on Fisheries (GFCM-SAC), plays a critical role in fisheries governance, having the authority to adopt binding recommendations for fisheries conservation and management. During the last years, advice on the status of the main stocks in the Mediterranean and Black Sea has been provided both by GFCM-SAC and EU-STECF, often without a clear coordination and a lack of shared rules and practices. This has led in the past to: i) duplications of the advice on the status of the stocks thus adding confusion in the management process and, ii) a continuous managers’ interference in the scientific process by DG MARE officials hindering its transparency and independence. Thus, it is imperative that this stalemate is rapidly resolved and that the free role of science in Mediterranean fisheries assessment and management is urgently restored to assure the sustainable exploitation of Mediterranean marine resources in the future., SI

The Alboran Sea and the Balearic Islands are two contrasting areas in terms of primary productivity. The former is among the most productive areas of the whole Mediterranean Sea, whereas the Balearic Islands is among the less productive ones in the western Mediterranean. The two areas also show different patterns in the bottom trawl fishing footprint. In the Alboran Sea, the fishing effort on the upper slope is much higher than in Balearic Islands. However, the opposite applies to the middle slope, the vast majority of it remaining unexploited in Alboran Sea, whereas a widespread fishery targeting blue and red shrimp Aristeus antennatus develops in Balearic Islands. Galeus melastomus is a small demersal shark species inhabiting slope bottoms, where adults and juveniles are segregated and concentrate in the middle and upper slope, respectively. It feeds intensively on mesopelagic preys which, in turn, feed on low trophic level organisms close to primary producers. In this work we aimed to study the effect of surface primary production on the condition of deep sea demersal communities. We compared the condition, diet and potential intra- and inter-species competition for feeding resources in the juveniles of G. melastomus between Alboran Sea and Balearic Islands. The comparisons of Le Cren’s relative condition factor, and hepatosomatic and digestivosomatic indices evidenced an opposite pattern to that a priori expectable: better condition in the less productive area. The analysis of stomach contents showed similar diets in both areas, but lower food ingestion in Alboran Sea than in Balearic Islands. Different abundances of potential intra- and inter-specific competitors for feeding resources in the two areas, apparently linked to the different fishing footprints, seems the most likely explanation for the better nourished individuals in Balearic Islands. Whereas juveniles of G. melastomus dominate the shark community in the Balearic Islands upper slope, where the presence of adults of this species is almost negligible, in Alboran Sea this stratum is dominated by adults and potential competitors of other small demersal shark species. All shark species together, including G. melastomus, showed abundances 38% higher in Alboran than in Balearic Islands. Our results show that condition of deep sea demersal fish is ruled by complex inter-relationships among different factors, needing the combination of biological, ecological and fisheries knowledge to understand its variability., SI

Overexploitation and climate change are increasingly causing unanticipated changes in marine ecosystems such as higher variability in fish recruitment or shifts in species dominance and distribution that alter the productivity of fish stocks. This study analyses how external and internal drivers influence population dynamics of hake (Merluccius merluccius), white anglerfish (Lophius piscatorius), four-spot megrim (Lepidorhombus boscii), and horse mackerel (Trachurus trachurus) of Iberian Peninsula waters of the Northeast Atlantic across different spatiotemporal scales. Available spawning stock biomass and recruitment have been used as biological data, whereas fishing mortality, demographic data as well as climatic and oceanographic data have been used as drivers. The obtained results indicate that population dynamics of these species are mainly driven by oceanographic variability at regional scale along with fishing pressure and demographic factors, while the impact of large-scale climate indices was minimal. The identified variables represent relevant oceanographic regional processes candidate to be potentially integrated into the stock assessment models and management procedures of these important fishery resources, Sí

Long fisheries time series allow the review of baselines and inform our knowledge of past events that have conditioned the recent history of the stocks. In this study, we investigated trends in fisheries landings data for the most representative Atlantic and Mediterranean demersal fisheries off the Spanish Iberian Peninsula and the Balearic Islands (1933–1986). The aim was to analyse the evolution of demersal species exploitation and detect changes in landings and fishing tactics. Ten species were selected, which included teleosts, crustaceans, and cephalopods. Results indicated a decrease in Landings Per Unit of Capacity (LPUC) in six of the species examined. While in the Atlantic the process of substitution or incorporation of new species to the fisheries occurs progressively, in the Mediterranean this incorporation occurs simultaneously for many of the species. Four main fishing tactics (landing pattern obtained from the classification analysis of landings per species) were identified. Geographically nearby and connected regions developed similar fishing tactics to each other, and also changed over time. While the fleets from isolated regions were more specialized, and only carrying out one fishing tactic during the study period. Improvements in LPUC with the implementation of new technology and legislative and management measures were not observed., SI

The high species richness, coupled with high proportion of endemism, makes the Mediterranean one of the world’s ‘biodiversity hotspots’. However, the continuous increase in fisheries in the last few decades has led to the overexploitation of their main commercial stocks. Using fishery-independent data collected under the framework of the MEDITS trawl surveys carried out over the last 20 years, we study the demersal fish diversity pattern in the Mediterranean at a large spatial and temporal scale to determine whether it is being affected by the general fishing overexploitation of the demersal resources. The detected diversity trends are compared with the spatio-temporal variation in bottom trawl fishing effort in the Mediterranean. Our results show a stability and even recovery of demersal fish diversity in the Mediterranean together with higher diversity values on the continental shelves of the Balearic Islands, Sardinia, Sicily and the Aegean Sea. At large temporal and spatial scales, the high diversity of demersal assemblages in the Mediterranean is associated with a reduction in bottom trawl fishing effort. The inclusion of species other than target ones through diversity indices is important in the implementation of an ecosystem-based fisheries management., Sí

Nearly 75% of European fishing vessels belongs to small-scale fisheries (SSF). However, SSF have received little attention compared to industrial fisheries. In the Mediterranean Sea, where the SSF traditionally had a high socio-economic relevance, there is a widespread interest in securing its sustainable exploitation and viability. Here we analyze the SSF from Mallorca (Balearic Islands) using fishery statistics from the last 25 years (1990–2014). Although fleet size declined markedly (−55%), landings remained constant which might be related to different, not mutually exclusive explanations such as a decrease in unreported catches, stagnant and closed market or technological creeping. Multivariate analysis revealed eight different fishing tactics corresponding to the main target species. Aggregated, these eight species accounted for 52% and 71% of SSF landings weight and value, respectively. The fishery of these species is markedly seasonal and the landings of most of them showed important fluctuations but no clear trends. In contrast with the claims of SSF having lower impact on the natural resources than other fisheries, surplus production models revealed a generalized overexploitation of these target stocks, especially for the most high-valued species. Simulations with a bioeconomic model showed that fishing effort reductions of 38% would improve the health of fish stocks while increasing the economic profits to as much as 15% from current profits. If all stocks were kept below their MSY level, the reduction in fishing effort would have to be of 53% from current values. If the economic yield from the fishery was to be maximized (MEY), fishing effort would need to be reduced by 28%. Owing to important quantities of unreported catches in the most high-valued species, output values of the stock status indicators and the bioeconomic modelling should be taken with care beyond tracking trends in the fishery, SI

16 pages, 7 figures, 3 tables, 1 appendix supplementary material http://dx.doi.org/10.1016/j.pocean.2016.07.006, The morphological and functional traits of fishes are key factors defining the ecological and biological habits of species within ecosystems. However, little is known about how the depth gradient affects these factors. In the present study, several demersal fish assemblages from the Balearic Islands (western Mediterranean Sea) along a wide depth range (40–2200 m) were morphologically, functionally and ecologically described. The morphological characterization of communities was performed using geometric morphometric methods, while the functional structures were obtained by the functional categorization of species and the application of principal coordinates analysis (PCoA). The results revealed that morphospaces presented less richness of body forms as depth increases, although they showed a progressive spreading of species toward the periphery, with a proliferation of more extreme body traits, demonstrating lower morphological redundancy. In addition, a trend toward the elongation of body shape was also observed with depth. Moreover, functional diversity increased with bathymetry up to 1400 m, where it sharply decreased downwards. This decrease was parallel to a progressive fall of H′ (ecological diversity) up to 2200 m. Functional redundancy progressively decreased until the deepest assemblage (more constantly in the deeper levels), which was almost exclusively dominated by benthopelagic wandering species feeding on suprabenthos. Redundancy analysis (RDA) demonstrated that both morphological and functional spaces showed high variation along the bathymetric range. Mantel test indicated that the majority of species presented similar spatial distribution within the morphospace and functional space, although in the functional space the more abundant species were always located at the periphery. These results demonstrate that the assessment of the morpho-functional variation between marine communities helps to understand the processes that affect the structure and functioning of communities, such as resource partitioning, trophic interactions, or interspecific relationships within ecosystem such as coexistence and dominance, Data of this study was obtained and financed within the framework of the projects MEDER, funded by the Spanish Institute of Oceanography (IEO), and ANTROMARE (Ref. CTM2009-12214-C02-01-MAR). [...] Marc Farré Foix acknowledges a pre-doctoral grant and a tuition fee to third cycle grant from the Government of Andorra, ATC010-AND and AMTC010-AND/2014, academic years: 2013–2014 and 2014–2015

The present work examines the spatio-temporal biomass trends of Mullus barbatus and Mullus surmuletus in the Mediterranean Sea through the analysis of a time series of data coming from the Mediterranean International Trawl Surveys (MEDITS), accomplished annually from 1994 to 2015. The biomass of both species showed clear declining trends below 150 to 200 m depth, which were steeper in the case of M. barbatus. Increases in temporal biomass trends were observed for M. barbatus from 2008 onward in most geographic sub-areas (GSAs), while stability was mostly observed for M. surmuletus. For both species, dynamic factor analysis revealed similarities among neighbouring GSAs and the subsequent cluster analysis identified two major GSA groups corresponding to the eastern and western basins of the Mediterranean. Overall, the results suggested that the combined effects of fishing and environmental conditions determine species abundance variations, but the relative importance of each component may vary among areas, Este trabajo examina las tendencias espacio-temporales de la biomasa de Mullus barbatus y Mullus surmuletus en el mar Mediterráneo, a través del análisis de una serie temporal de datos procedentes de las campañas internacionales de arrastre MEDITS en el Mediterráneo, realizadas anualmente entre 1994 y 2015. La biomasa de ambas especies mostró tendencias claramente decrecientes por debajo de 150-200 m de profundidad, que fueron más pronunciadas en el caso de M. barbatus. En la mayoría de las Sub-áreas Geográficas (SAGs), se han observado incrementos en las tendencias temporales de la biomasa de M. barbatus a partir de 2008, mientras las series de datos de M. surmuletus mostraron estabilidad en la mayoría de los casos. Para ambas especies, el análisis factorial dinámico reveló similitudes entre las SAGs vecinas y el posterior análisis de conglomerados identificó dos grupos principales de SAGs, correspondientes a las cuencas oriental y occidental del Mediterráneo. En general, los resultados sugieren que los efectos combinados de la pesca y las condiciones ambientales determinan las variaciones en la abundancia de estas especies, pero la importancia relativa de cada componente puede variar entre las áreas.

The large-scale distribution pattern of megafauna communities along the Mediterranean middle slope was explored. The study was conducted between 500 and 800 m depth where deep-water fishery occurs. Although community studies carried out deeper than 500 m are partly available for some geographic areas, few large-scale comparative studies have been carried out. Within the framework of the MEDITS survey programme, we compared the megafauna community structure in ten geographical sub-areas (GSAs) along the Mediterranean coasts. Additionally, the spatial distribution of fishing was analysed using vessel monitoring by satellite information. Overall, the community showed a significant difference between sub-areas, with a decreasing eastward pattern in abundance and biomass. Longitude was the main factor explaining variation among sub-areas (by generalized additive models). However, we found a region which did not follow the general pattern. GSA 6 (northern Spain) showed significantly lower abundance and a different composition structure to the adjacent areas. The decrease in community descriptors (i.e. abundance and biomass) in this area is probably a symptom of population changes induced by intense fishery exploitation. Overall, a combination of environmental variables and human-induced impacts appears to influence the bentho-pelagic communities along the slope areas of the Mediterranean., En este estudio se describe la estructura y patrones de distribución de la comunidad de megafauna que habita en el margen continental medio a lo largo del Mediterráneo. El estudio se realizó entre los 500 y 800 m, coincidiendo espacialmente con las pesquerías de profundidad. A pesar de que se conoce parcialmente la estructura de las comunidades que habitan por debajo de 500 m, existe la necesidad de estudiar estas comunidades a una escala espacial más amplia. Dentro del marco del proyecto internacional MEDITS, se comparó la estructura de las comunidades en diez sub-áreas geográficas (GSAs) a lo largo de las costas mediterráneas. Además se analizó la distribución espacial del esfuerzo pesquero utilizando la información de los datos de seguimiento de buques. En general los resultados mostraron diferencias significativas entre subáreas mostrando un patrón decreciente en los valores de biomasa hacia el este, siendo la longitud el principal factor explicativo del modelo de distribución (GAMs). Sin embargo, encontramos una subárea que no seguía el patrón general, la GSA6 (norte de España). La GSA6 mostró una biomasa y estructura de la comunidad diferente a las áreas adyacentes. La disminución de la biomasa en esta área parece ser un síntoma de los cambios poblaciones causados por la elevada intensidad de pesca en la zona. Los resultados sugieren que la distribución y estructura de las comunidades bento-pelágicas parecen estar moduladas por la combinación de las variables ambientales y los impactos producidos por la actividad humana.

Microichthys coccoi Rüppell, 1852 was originally described based on a stranded individual collected in the Strait of Messina, Sicily, central Mediterranean. The distribution range of the species is poorly known, as very few individuals have been recorded from Italy, Greece, and Turkey in the Mediterranean, and from the Azores in the north eastern Atlantic. The aim of this study was to report the presence of M. coccoi from the Balearic Islands (western Mediterranean). The history of species’ known records is compiled and its presence in the Atlantic is discussed, SI

16 pages, 5 figures, 2 tables, In marine ecosystems, the most significant migration observed in terms of biomass distribution is the one connected with the vertical movements in the water column. In the present study, the vertical profiles of the mesopelagic shrimps Gennadas elegans, Eusergestes arcticus, Sergia robusta, and the epipelagic Parasergestes vigilax in the Balearic Sea (western Mediterranean), during the stratified (summer) and non-stratified (autumn) hydrographic conditions, were investigated through their ontogeny, from the larval to adult stages. The mesopelagic adults were observed to move down to the deeper layers during the night more than during the daylight hours. Most larvae aggregated within the limits of the upper water column. The P. vigilax larvae were collected only during the stratified period. The first two larval stages vertical distribution indicates that the mesopelagic crustacean spawning could occur at greater depths. During the non-stratified period, the larvae of the mesopelagic species tended to remain at about 500 m depth at night, rising towards the upper layers at sunrise. Vertical patterns are discussed, as strategies associated with predator–prey trade-offs. To our knowledge, the present study is the first such attempt to jointly analyze the vertical migrations of the developmental stages of the pelagic shrimps in the Mediterranean Sea, The research was performed within the framework of the IDEADOS (CTM2008-04489-C03-01) project, funded by the National Plan I + D+i. A. P. Torres and M. Hidalgo were funded by a pre-doctoral FPI Fellowship and a post-doctoral contract, respectively, bestowed by the regional government of the Balearic Islands, Conselleria d’Educació, Cultura i Universitats, and selected as part of an operational program co-financed by the European Social Fund

The present study analysed the effect of three different benthic habitats, the maerl, Peyssonnelia red algal beds and sandy bottoms, on the condition of two nekto-benthic fish species: Serranus cabrilla and Trigloporus lastoviza. Sampling was conducted during the MEDITS 2010 and 2011 surveys around the Balearic Islands. The condition of the spawning females of both species was determined by using i) biochemical measurements of proteins and lipids in the muscle, liver and gonads, and ii) weight at length relationships based on eviscerated, liver, and gonad weights. Moreover, based on the total weight at length relationship, the mean somatic condition (SC) of the sexually inactive individuals of S. cabrilla and males of T. lastoviza was calculated. Lipid reserves were higher in the livers of S. cabrilla and T. lastoviza from the maerl beds. Additionally, S. cabrilla showed higher lipid reserves in the gonads both in the maerl and Peyssonnelia beds. The mean weights of the liver and gonads at a given individual length revealed the same pattern as the lipids, whereas the mean eviscerated weight was higher in the maerl beds but only for S. cabrilla. A positive correlation was detected between the SC and the biomass of the algal species characterizing the maerl beds for both S. cabrilla and T. lastoviza. The high habitat quality of the red algal beds off the Balearic Islands increased the condition of nekto-benthic fish. In oligotrophic areas, such as the archipelago, these “oases” could help fish to maintain healthy populations.

The spotted catshark (Scyliorhinus canicula) and the blackmouth catshark (Galeus melastomus) are demersal sharks showing a distinct bathymetric distribution in the western Mediterranean. Together, both species represent more than 85% of the total abundance of demersal chondrichthyans in this Mediterranean basin. Our study provides a complete analysis of the genetic population structure, connectivity and demographic history of both species. Sampling was performed across four geographical subareas (GSAs) established by the General Fisheries Commission for the Mediterranean in the western Mediterranean: the northern Alboran Sea (GSA01), Alboran Island (GSA02), Balearic Islands (GSA05) and northern Spain (GSA06). Three mitochondrial fragments were analyzed for both species, and 12 microsatellite loci for S. canicula. We found contrasting patterns of population structure and connectivity in both species. Scyliorhinus canicula displayed significant genetic differences and low connectivity between some GSAs corresponding to different sub-basins (Alboran vs. Balearic). In contrast, G. melastomus showed absence of a population structure and high connectivity between GSAs. These findings are in accordance with the fact that both species exhibit different dispersal behaviors, which leads to distinct bathymetric distributions. Contrasting demographic histories were also identified: Scyliorhinus canicula revealed a recent stable population, with evidence of bottlenecks in the past, which may be related to Pleistocene glacial periods; whereas G. melastomus showed a recent population expansion. Altogether, our findings indicate a mismatch between fishery subareas and population structure for both sharks, which must be considered for fisheries management purposes.

The present study confirms the presence of the Norwegian skate Dipturus nidarosiensis (Storm, 1881) in the Mediterranean Sea, by means of morphological traits and molecular markers providing the first record of this species in the Alboran Sea. Cannas et al. (2010) reported D. nidarosiensis for the first time in the Mediterranean from specimens captured in the central western basin, but Ebert & Stehmann (2013) and Stehmann et al. (2015) considered these records "likely refer to the smaller morphotype, Dipturus sp.", a species not yet described. Eight specimens of the Dipturus genus (Rajiformes: Rajidae) were caught off the Alboran Island (western Mediterranean) in 2012, 2013 and 2016, between 620 and 819 m depth. These specimens showed morphometric diagnostic features corresponding to those of Norwegian skates from the Northeast Atlantic and the central western Mediterranean Sea. Moreover, the Alboran individuals were genetically compared to Northeast Atlantic specimens available in GenBank by means of two mitochondrial DNA fragments: cytochrome c oxidase subunit I (COI) and cytochrome b (Cytb). Analyses showed that the Northeast Atlantic Norwegian skate specimens and the Alboran Sea ones were genetically similar and shared haplotypes, corroborating the identification of the Alboran individuals as Dipturus nidarosiensis. However, they were different from other Dipturus species distributed throughout the Northeast Atlantic and the Mediterranean Sea. Our results confirm the occurrence of this deep-sea large skate species in the Mediterranean, although the IUCN Red List of Threatened Species does not consider it possible (Stehmann et al., 2015), SI

The serious overfishing of most Mediterranean stocks demands urgent reforms of the management measures aiming to guarantee the sustainability of resources, notably when compared with the improvement observed in other European areas. The new EU Common Fisheries Policy (CFP) constitutes an excellent opportunity to introduce the changes needed for such a reform. According to this CFP, all European fish stocks should be brought to a state where they can produce at MSY by 2020 at the latest. The CFP also establishes that the objective of sustainable exploitation should be achieved through multiannual plans (MAPs) adopted in consultation with relevant stakeholders having fisheries management interests such as fishermen, non-governmental organizations, and policy makers. Together with the MSY and MAP approaches, the new CFP contains several other measures, directed to guarantee the ecological and socio-economic sustainability of fisheries by means of the implementation of the ecosystem approach to fisheries management (EAFM). With this new perspective, the CFP wants to avoid past failures of fisheries management based on monospecific approaches. This study is a first step toward the application of the EAFM in the Balearic Islands by means of the development of a harvest strategy with defined objectives, targets, limits, and clear management control rules aimed at optimizing socioeconomic and ecological objectives in the framework of the new CFP. Different management scenarios designed to achieve that goal were modeled for the main demersal commercial fisheries from the study area, the bottom trawl, and small-scale fisheries. The work begins with a general description of those fisheries, their main fishing grounds, and assessments of the exploitation status of the main target stocks in order to establish the current situation. Secondly, alternative management scenarios to maximize catch and profits while considering societal objectives were evaluated by means of bio-economic models. Thirdly, management measures were provided based on the previous modeling and discussions with stakeholders. Finally, a monitoring scheme was outlined to assess the progresses of the proposed management actions. This work is intended to be a working example of co-management (fishers, policy-makers, and scientists) in the Mediterranean in the framework of the new EU CFP, SI

Measures of biodiversity change may be useful as indicators if they are responsive to manageable drivers of biodiversity loss. However, there are many candidate indicators that are considered to be robust to survey artifacts and sensitive to manageable impacts. Using extensive survey data on demersal fish assemblages around the Balearic Islands (western Mediterranean) we analyze relationships among ‘traditional’, taxonomic and functional diversity indices, to identify a minimum set of indices that provide a good representation of the different aspects of diversity. Secondly we model the responses of the demersal fish community diversity to bottom trawl fishing pressure. To do so, we used two different approaches: (i) considering fishing effort and depth as continuous explanatory variables; and (ii) grouping samples according to bathymetric sampling strata and contrasting levels of fishing effort. The results show that diversity can be described using different complementary aspects such as species richness, evenness, and the taxonomic and functional breadth of the species present in a given community, displaying different responses to fishing pressure. However, the changes in diversity in response to fishing may only be detectable in those communities where the levels of fishing pressure have remained relatively low. When communities have been exposed to high levels of fishing pressure for a long period, the relevant changes in diversity may have happened long before the onset of monitoring of the fishery, and hence it may be too late to detect differences between levels of fishing effort. This seems to be the case on the middle slope of the Balearic Islands, where vulnerable species have disappeared or are very infrequent, and have been replaced by species better-adapted to fishing impacts, SI

The objective of this study was to determine the population distribution and some biological aspects for fish stock assessment of the greater forkbeardPhycis blennoidesalong the Algerian basin. The distribution ofP. blennoides(3418 individuals) was studied using data collected between 170–779 m depth during two bottom trawl surveys developed on 2003 and 2004. Additionally, some biological parameters were obtained from 1050 individuals sampled from commercial fisheries in Algerian ports (i.e. Annaba, Azeffoun, Dellys, Cap Djinet, Zemmouri, Bouharoun, Algiers, La Madrague, Cherchell, Tenes and Mostaganem) during the period 2013–2017.P. blennoidessampled from bottom trawl surveys showed a depth related distribution with the largest individuals being found at 600–800 m depth and the smallest at shallower depths. Density and biomass varied with depth and density also with longitude, while biomass showed no pattern with longitude. Recruitment was recorded in the eastern sector of Algeria during winter, for individuals sampled by bottom trawl surveys. YoungP. blennoidesentered commercial fisheries in summer, with an overall sex ratio skewed towards males (1F:2.18M). The size at first maturity (L50) was 24.30 cm and 30.39 cm for males and females, respectively. The age at 50% maturity was 2–3 years for specimens collected by a bottom trawl survey in 2003 and commercial fisheries, but 3–4 years for the bottom trawl survey in 2004.

Decapod crustaceans are the main target species of deepwater bottomtrawl fisheries in the Balearic Sea but little is known about their larval stages. This work focuses on the species composition of the decapod larval community, describing the main spatio-temporal assemblages and assessing their vertical distribution. Mesozooplankton sampling was carried out using depth-stratified sampling devices at two stations located over the shelf break and themid slope, in the north-western and southern Mallorca in late autumn 2009 and summer 2010. Differences among decapod larvae communities, in terms of composition, adult's habitat such as pelagic or benthic, and distribution patternswere observed between seasons, areas and station. Results showed that for both seasonsmost species and developmental stages aggregatedwithin the upperwater column (above 75 mdepth) and showed higher biodiversity in summer compared to late autumn. Most abundant species were pelagic prawns (e.g., Sergestidae) occurring in both seasons and areas. The larval assemblages' distributions were different between seasonal hydrographic scenarios and during situations of stratified and non-stratified water column. The vertical distribution patterns of different larval developmental stages in respect to the adult's habitat were analyzed in relation to environmental variables. Fluorescence had the highest explanatory power. Four clearly different vertical patterns were identified: two corresponding to late autumn, which were common for all the main larval groups and other two in summer, one corresponding to larvae of coastal benthic and the second to pelagic species larvae., SI

This short-term study on commercial discards was carried out in fishing grounds around Gökçeada Island in the northeastern Aegean Sea, a geographic area where fisheries information is rather limited. A total of 28 bottom trawls were performed between 70 and 410 m depth from December 2009 to February 2010. All the samples were collected on board a commercial trawler under commercial fishing conditions. A total of 3143 kg of biomass was caught in 28 valid hauls. Landings accounted for about 67% of the total catch while the remaining 33% was discarded. Fish species comprised 85% of the total catch and their composition could be divided into four main groups related to depth: shallow shelf (70 to 88 m), deep shelf (155 to 180 m), shelf break (196 to 276 m), and upper slope (307 to 410 m). Fish dominated the abundance and biomass of both landings and discards in all bathymetric strata. Echinoderms also accounted for a large proportion of the discards. Mean total catches varied between 78.4 kg/h on the shallow shelf and 38.1 kg/h on the shelf break with no differences in the landing biomass between groups, but with slightly higher discards over the shallow shelf. Taking into account the preliminary nature of the findings, based on a short-term analysis, the minimum mesh size and minimum landing size currently applied in the Turkish bottom trawl fishery are not sufficient to reduce discards and to protect juveniles of commercially important species in the northeastern Aegean Sea. Este estudio a corto plazo sobre los descartes de la flota comercial de arrastre se llevó a cabo en las zonas de pesca alrededor de la isla Gökçeada en el noreste del mar Egeo, una zona geográfica en la que la información sobre las pesquerías es bastante limitada. Se realizaron un total de 28 pescas de arrastre de fondo entre 70 y 410 m de profundidad de diciembre 2009 a febrero de 2010. Todas las muestras se recogieron a bordo de un embarcación de pesca de arrastre siguiendo las mismas condiciones de pesca comercial. Se capturaron un total de 3143 kg de biomasa en 28 lances válidos. Los desembarques comerciales representaron alrededor del 67% de la captura total, mientras que el resto (33%) se descartó. El 85% de la captura total estuvo compuesta por especies de peces. La composición específica se pudo separar en cuatro grupos principales relacionados con la profundidad : la plataforma poco profunda (70 a 88 m), la plataforma profunda (155-180 m), el borde inferior de la plataforma (196 a 276 m) y el talud superior (307-410 m). Los peces dominaron la abundancia y biomasa tanto de los desembarques comerciales como de los descartes en todos los estratos batimétricos. Además los equinodermos también fueron un grupo importante de los descartes. La media de las capturas totales varió entre 78.4 kg/h en la plataforma poco profunda y 38.1 kg/h en el borde de la plataforma, sin diferencias en la biomasa desembarcada entre los dos grupos, pero siendo los descartes ligeramente superiores en la plataforma poco profunda. Teniendo en cuenta el carácter preliminar de los resultados, obtenidos sobre la base de un análisis a corto plazo, el tamaño mínimo de malla de la red y la talla mínima de las especies comerciales aplicada hoy en día en la pesquería de arrastre de fondo de Turquía no son suficientes para reducir los descartes y proteger a los juveniles de las especies de importancia comercial en el Mar Egeo nororiental.

The improvement of fishing technology has been detrimental to the sustainability of fisheries, which is particularly clear for the bottom trawl fishery. Reducing its environmental impact is a key point for the development of a more sustainable fishery. The present work analyzed different possibilities to mitigate the impact of gears on the seabed and to increase the efficiency of the bottom trawl fishery of the Western Mediterranean. The analysis of three experiments showed that innovative technical and regulation measures can lead to benefits such as the reduction of fishing effort, the improvement of the cost-benefit relation and the reduction of the direct impact on the seabed and the indirect effect on the ecosystems through reduce discards and the emission of CO2 into the atmosphere. After years of studies focused on improving the sustainability of this fishery, it's about time to turn this improvement into reality, SI

11 pages, 6 figures, 4 tables, 1 appendix, The bottom morphology, the surface sediments and the epibenthic community of two adjacent areas within the fishing ground traditionally known as Pesquera Rica (Balearic Islands) were characterized using multibeam echosounder, van Veen dredge and beam trawl. Red algae beds predominate in both areas, but one has been exploited by trawling since at least 90 years ago, whereas the presence of natural barriers prevents this fishing activity in the other one. Comparisons between the two areas showed a biomass reduction of 46.8 and 39.3% of dominant red algae taxonomic groups Peyssonneliaceae and Corallinophycidae, respectively, in the trawled area (TA). Similarly, both mean abundance and biomass of most groups of fauna were higher in the not trawled area (NTA). N biodiversity index showed higher mean values of algae species in NTA than in TA (7.0 and 4.9, respectively), whereas no differences were detected neither for sessile nor for mobile fauna. SIMPER analysis showed that large species of both sessile and mobile epibenthic fauna (e.g. the ascidia Polycarpa mamillaris and the echinoderm Spatangus purpureus, respectively) presented higher abundance and contribution to within area similarity in NTA than in TA. In coincidence, these are the most abundant epibenthic species in the commercial hauls from the Pesquera Rica. The relatively low fishing effort and the gears used, addressed to avoid large catches of algae allowing longer hauls, may explain the subsistence of red algae beds in the Balearic Islands trawl fishing grounds. However, the detrimental effects shown here claim for urgent management measures aiming to preserve these beds., Surveys at sea in 2009 and 2014 were carried out within the project DRAGONSAL (Caracterización del Ecosistema Bentónico de la Plataforma costera del area comprendida entre sa Dragonera, cap de ses Salines y Cala Figuera (Mallorca)), co-funded by the Instituto Español de Oceanografía and the Balearic Islands government . Analysis of the data has been done within the framework of the projects DRAGONSAL and LIFE-IP INTEMARES “Integrated, Innovative and Participatory Management for N2000 network in the Marine Environment” (LIFE15 IPE/ES/000012)

Accumulating evidence shows that fishing exploitation and environmental variables can synergistically affect the population dynamics of exploited populations. Here, we document an interaction between fishing impact and climate variability that triggered a synchronic response in the population fluctuations of six exploited species in the Mediterranean from 1965–2008. Throughout this period, the fishing activity experienced a sharp increase in fishing effort, which caused all stocks to shift from an early period of underexploitation to a later period of overexploitation. This change altered the population resilience of the stocks and brought about an increase in the sensitivity of its dynamics to climate variability. Landings increased exponentially when underexploited but displayed an oscillatory behaviour once overexploited. Climatic indices, related to the Mediterranean mesoscale hydrography and large-scale north Atlantic climatic variability, seemed to affect the species with broader age structure and longer lifespan, while the global-scale El Niño Southern Oscillation index (ENSO) positively influenced the population abundances of species with a narrow age structure and short lifespan. The species affected by ENSO preferentially inhabit the continental shelf, suggesting that Mediterranean shelf ecosystems are sensitive to the hydroclimatic variability linked to global climate. (Oxford University Press)

The bottom trawl fishery developed on the slope off Balearic Islands (western Mediterranean) has been analysed from different sources of information: (i) data obtained during experimental bottom trawl surveys developed annually since 2001; (ii) daily sale bills from the bottom trawl fleet, available since 2000. Considering both hydrographical and geomorphologic conditions, the study area was divided in four geographical sectors. Multivariate techniques were applied to identify assemblages and their main species, and to investigate the influence of environmental variables in the slope communities. Fishery-independent and fishery-dependent indicators were calculated, both at specific and community level, for the assemblages identified. In all cases, they were summarised using the Traffic Light approach. Three assemblages have been identified in the slope trawl fishing grounds off the Balearic Islands: (1) the almost unexploited shelf break, where teleosts predominate; (2) the upper slope, where teleosts still predominate but crustaceans are also very important (with Nephrops norvegicus as target species); (3) and the middle slope, where crustaceans predominate (with Aristeus antennatus as target species). Depth was the main factor affecting the species composition of the assemblages, although other factors such as area, year and effort level also affect. Indicators estimated from both sets of data suggested an improvement in the state of N. norvegicus, although the results suggest the influence of other factors than fishing impact in the state of this resource. For A. antennatus, marked differences have been found depending on the data source. In the upper slope, indicators suggested an improvement in the state of this assemblage, which can be related to a decreasing trend found in the fishing effort exerted in this depth range. Indicators from the middle slope showed differences for both sets of data. The characteristics of both data sources and of the species analysed are discussed as responsible of these differences, Sí

1. The present study characterizes the macro-epibenthic assemblages, and the relationships between demersal species and benthic habitats on the shelf trawl fishing grounds off the Balearic Islands (western Mediterranean). 2. The data used were collected during experimental bottom trawl surveys from 2002 to 2005. A total of 157 samples from 38–255 m depth were analysed. 3. Three macro-epibenthic assemblages were identified in both the shallow (at 38–91 m) and deep shelf (90–255 m). Macroalgae bathymetric distribution was identified as the main factor explaining the segregation between shallow and deep shelf assemblages. 4. Two especially sensitive habitats were identified: maerl and crinoid beds; a third habitat was identified as Peyssonnelia beds, which represented the highest biomass on the whole shelf, with a similar species richness to the maerl beds. On the deep shelf, crinoid beds represented the highest biomass. 5. Habitat type had a significant effect on the distribution of demersal commercial species, most of them being more abundant in the two sensitive habitats mentioned and in the Peyssonnelia beds. Some species showed size-specific habitat preferences. 6. Fisheries management in the area should take into account the resilience of these benthic habitats, and their importance from both ecological and sustainable fisheries management perspectives. Copyright © 2008 John Wiley & Sons, Ltd.

Short-term temporal variability in deep-sea demersal fish assemblages is described for two slope areas characterised by different oceanographic conditions, which are situated north (Balearic sub-basin, BsB) and south (Algerian sub-basin, AsB) of the Balearic Islands (western Mediterranean). A total of 75 hauls were analysed from six bottom trawl surveys carried out in the two sub-basins. At BsB, surveys were designed for sampling different slope habitats during April 1991, December 1991, March 1992 and July 1992: (i) a submarine canyon at a depth of around 450 m, (ii) the upper slope at a depth of 600-650 m, and (iii) the middle slope at a depth of around 1200 m. At AsB, surveys were carried out during October 1996 and May 1998, along a continuous transect on the upper, middle and lower slope. The taxonomic composition, ecological parameters (number of species, abundance and biomass) and biomass spectra of the assemblages, as well as the length frequency distribution of the main species, were compared for different seasons and bathymetric ranges. Forty-four demersal species were captured in BsB and 38 in AsB. Helicolenus dactylopterus and Trachyrinchus scabrus were more abundant in BsB, and Hoplostethus mediterraneus, Galeus melastomus and Centroscymnus coelolepis in AsB. Depth was the determinant factor in all the analyses. Species-specific densities (abundance and biomass) showed significant differences between surveys, depth strata and their interaction in BsB. However, survey and its interaction with depth, were not significant in AsB. We also found significant differences in relation to depth and season for the three ecological parameters tested in BsB, but only significant differences in relation to depth in AsB. Biomass spectra showed large differences in relation to depth but only slight between-survey differences, which mainly occurred in the upper slope. The length frequency distributions of single species presented short-term temporal variations, mainly due to the varying presence of a larger proportion of small or large individuals. Depth, geographic area and sampling time were the main factors determining the species composition and structure of deep-sea slope demersal fish assemblages. The effects of short-term temporal variations were observed in both the replacement and the size structure of some dominant and subdominant species throughout the year. The different temporal variation effects observed between the two sub-basins might be related to differences in productivity and its transport to the benthos. © 2008 Elsevier Ltd. All rights reserved.

The red shrimp Aristeus antennatus is one of the target species of the bottom trawl fishery of the Balearic Islands. The objective of the present paper is to study the short spatial and temporal differences of this important economic resource between two different locations off Mallorca (Cabrera: CA; Soller: SO), where a fleet mobility pattern has been detected, and to study the influence of environmental conditions on this species. Six simultaneous bottom-trawl and oceanographic surveys were carried out at these two locations in order to collect data from the demersal species, hydrography (temperature and salinity), trophic resources and sediment characteristics. The commercial fleet from both locations was monitored by monthly on-board sampling, log-books and daily landings obtained from sales slips. Additional data was obtained from other fishing surveys. Short spatial and temporal differences have been detected between both locations. The population at CA was more demographically homogeneous, while that at SO showed important variations, like high abundance of juveniles recruiting to fishing grounds in autumn–winter and high abundance of large females during summer. Several differences have also been found in the biology of the species between locations, such as males were more abundant in SO than in CA. Also, the reproductive period started sooner in SO than in CA, and the condition of pre-spawning females was better in SO. The percentage of total lipids in the hepatopancreas was minimal during the spawning period, showing their importance as a reserve of energy for the ovary ripening. Water masses could play an important role in these differences, the characteristics of water masses being more stable in CA than in SO. Red shrimp adult females seemed to be more correlated with the warmer and more saline Levantine Intermediate Waters, while juveniles (males and females) and adult males were more correlated with the colder Western Mediterranean Deep Waters, detected only in SO during autumn–winter. Two different hypothesis of mobility patterns for the species are discussed in relation to these observed differences.

Hydroclimatic variability is one of the main factors that drives inter-annual changes in fish migration patterns. This study analyses the relationship between climate- oceanographic factors and migration of the Atlantic pomfret (Brama brama) in NE Atlantic waters. Geo-referenced catch data from logbooks of longliners operating in European Atlantic waters from 2002 to 2013 were linked to environmental indices at different temporal and spatial scales. Our results point to a strong influence of temperature at 200 m depth as the key factor along with the upwelling in the Galician (NW Iberian) waters. However, sea surface temperature (SST) indirectly affects the geographical display of Atlantic pomfret migration, and large migrations are observed in scenarios of high SSTs in the migratory area (c. above 14.7°C). Migrations are constrained during years when temperatures are below this threshold. A longer time-series of annual landings (1950–2013) supports this evidence and highlights the significant influence of temperature at 200-m depth along with the landings of the previous year. Length frequency distributions suggest an increase in size between consecutive seasons supporting the hypothesis that migration is a feeding strategy and a return to tropical waters of origin for spawning. Our study shows that the temperature of intermediate waters is a key variable in determining the northward migration of the Atlantic pomfret whereas density-dependence and surface climatic conditions trigger secondary effects on the migration pattern of this species. Versión del editor 2,0440

Helicolenus dactylopterus and Merluccius merluccius are widely distributed on the continental slopes of the Atlantic and Mediterranean and have quite different life histories. Both are commercially exploited, but little is known about their stock structure. Fish otolith composition is thought to reflect both endogenous processes and external factors, some of which relate to the surrounding environment, and therefore may be used as a tool for stock discrimination. The elemental composition of sagittal otoliths was examined using both solution-based inductively coupled plasma mass spectrometry of the whole otolith and laser-ablation analysis of the otolith nucleus. The relative concentrations of strontium, barium, and copper in dissolved whole otoliths contributed to the discrimination between H. dactylopterus samples from different geographic areas. Surface analysis of the otolith nucleus did not allow separation of geographic groups. For M. merluccius, separate analyses of the whole otolith data for the Atlantic and Mediterranean samples gave a clear distinction of the different groups within each ocean basin. Analysis of the M. merluccius nucleus composition indicated some differences in elemental concentration among both Atlantic and Mediterranean samples. Magnesium and lead were important elements in separating the groups in the Atlantic, and barium, strontium, and lead were important in the Mediterranean. © 2005 International Council for the Exploration of the Sea. Published by Elsevier Ltd. All rights reserved.

Publicación online disponible en: http://www.icm.csic.es/scimar/index.php [EN] Data collected south-west of the Balearic Islands (Western Mediterranean) on two cruises, Quimera-I (October, 1996) and Quimera-II (May, 1998), were used to establish general ecological patterns in deep-sea fish assemblages. A total of 39 trawls were taken at depths between 400 and 1714 m. Fish assemblages were analysed in terms of species composition, ecological parameters and biomass spectra. Differences in species composition between cruises and depth (Upper slope: 400-800 m, Middle slope: 801-1400 m and Lower slope: 1401-1714 m depth) were evaluated using multivariariate analysis. The most important feature was the existence of a biomass peak at intermediate depths. Moreover, the analysis of the biomass spectra indicated the absence of large individuals at the shallower depth interval considered. To determine the causes of the biomass peak on the middle slope four hypothesis were explored: (1) species richness is higher on the middle slope; (2) the fish assemblage from the middle slope can be characterised by the highest abundance (number of fish/area); (3) species found on the middle slope are larger (the species assemblage is built up by larger species); and (4) there is a trend for the specimens of several species to be larger at the middle slope. The data gathered support that the biomass peak is better explained by the existence of abundance peaks of medium and large-sized species, and by the presence of some of the largest individuals of other large-sized species, in both cases related to specific depth size trends which do not always follow a bigger-deeper trend. [ES] Los datos analizados se han recogido al sureste de las Islas Baleares en dos campañas Quimera-I (Octubre, 1996) y Quimera-II (Mayo, 1996). Se realizaron un total de 39 pescas de arrastre entre 400 y 1714 m de profundidad. Se analizó la composición específica, parámetros ecológicos y espectros de biomasa de la comunidad íctica de profundidad. La característica más importante fue la existencia de un pico de biomasa a profundidades intermedias. El análisis de los espectros de biomasa indicó que no aparecían individuos de gran tamaño a menor profundidad. Las causas que pueden determinan la aparición de este pico de biomasa en el talud medio, se han examinado a partir de cuatro alternativas: (1) mayor riqueza específica a profundidades intermedias, (2) mayor abundancia de algunas especies en este intervalo de profundidad; (3) mayor tamaño de las especies, (4) tendencia de los ejemplares de algunas especies a ser más grandes a profundidades intermedias. La principal causa que puede explicar este pico de biomasa está relacionada con las respuestas individuales y específicas al gradiente batimétrico, ya que la abundancia de ciertas especies de tamaño medio y grande presenta un pico en esta profundidad, y además individuos de gran talla de otras especies de gran tamaño también son más abundantes. Ambas posibilidades no siempre se relacionan con una tendencia al aumento de la talla con la profundidad. This paper is a result of the European Project “Developing deep-water fisheries: data for their assessment and for understanding their interaction with an impact on a fragile environment” (EU FAIR Project CT 95-0655; European Commission DG XIV Fisheries).

The regular presence of the white shark, Carcharodon carcharias, off the Balearic Islands (western Mediterranean) is shown from 27 captures carried out with trap nets between the 1920s and 1970s and from eight attacks on cetaceans and marine turtles from the 1990s to the present. The geographic distribution, seasonality and population structure of the species in the area are analysed and discussed in relation to environmental conditions and to the proposed distribution of this species in the Mediterranean Sea.

Weight-length relationships (WLRs) are presented for 103 fish species inhabiting littoral to lower slope habitats of the Balearic Islands and the Iberian coast (western Mediterranean). Samples were collected using seven types of fishing gear and at depths ranging from 0.5 to 1713 m. Captures were made between the years 1991 and 2001. The b values in the WLR W = aLb varied between 2.072 and 3.847 and showed a mean value of 3.03 (S.E. = ±0.03). Whenever possible, the b values for the species obtained both in this study and some of the previously reported in the Mediterranean Sea were compared, showing the existence of spatial variation whose causes are discussed. © 2002 Elsevier Science B.V. All rights reserved.

The analysis of 131 hauls from four bottom trawl fishing surveys carried out between depths of 46 and 1713 m in two different areas off the Balearic Islands yielded a total of 23 elasmobranch species belonging to eight families. Cluster analysis and multidimensional scaling (MDS) ordination were applied to detect zonation patterns and some ecological parameters (e.g. species richness, abundance and biomass, mean weight, diversity and evenness) were calculated for each assemblage. For each area, analysis of similitude (ANOSIM) and similarity percentage analysis (SIMPER) were also applied to detect differences between seasons and depths. For the most important species (Galeus melastomus, Scyliorhinus canicula, Centroscymnus coelolepis, Etmopterus spinax, Squalus blainvillei, Raja naevus, Raja asterias, Raja clavata, Raja miraletus and Raja oxyrhinchus), abundance and size distributions were analysed by depth.

According to the Common Fisheries Policy (CFP), all European sh stocks should be brought to a state where they can produce at MSY by 2015 wherever possible or by 2020 at the latest. Despite the high socioeconomical importance of cephalopods in the Mediterranean and the increased availability of stock assessments during the recent past, only few European cephalopod stocks have been assessed to date. Surplus production models were applied to analyse the exploitation state of octopus and cuttle sh stocks from the Balearic Islands (western Mediterranean) to estimate how far away they were from the MSY target established by the CFP using a long-term data series (1977–2013). The stocks were overexploited (cuttle sh) or about to be overexploited (octopus) during the late 1970s; this state remains even now and will only recover from overexploitation by 2020 if severe measures are taken., SI

Increasing human pressures and global environmental change may severely affect the diversity of species assemblages and associated ecosystem services. Despite the recent interest in phylogenetic and functional diversity, our knowledge on large spatio-temporal patterns of demersal fish diversity sampled by trawling remains still incomplete, notably in the Mediterranean Sea, one of the most threatened marine regions of the world. We investigated large spatio-temporal diversity patterns by analysing a dataset of 19,886 hauls from 10 to 800 m depth performed annually during the last two decades by standardised scientific bottom trawl field surveys across the Mediterranean Sea, within the MEDITS program. A multicomponent (eight diversity indices) and multi-scale (local assemblages, biogeographic regions to basins) approach indicates that only the two most traditional components (species richness and evenness) were sufficient to reflect patterns in taxonomic, phylogenetic or functional richness and divergence. We also put into question the use of widely computed indices that allow comparing directly taxonomic, phylogenetic and functional diversity within a unique mathematical framework. In addition, demersal fish assemblages sampled by trawl do not follow a continuous decreasing longitudinal/latitudinal diversity gradients (spatial effects explained up to 70.6% of deviance in regression tree and generalised linear models), for any of the indices and spatial scales analysed. Indeed, at both local and regional scales species richness was relatively high in the Iberian region, Malta, the Eastern Ionian and Aegean seas, meanwhile the Adriatic Sea and Cyprus showed a relatively low level. In contrast, evenness as well as taxonomic, phylogenetic and functional divergences did not show regional hotspots. All studied diversity components remained stable over the last two decades. Overall, our results highlight the need to use complementary diversity indices through different spatial scales when developing conservation strategies and defining delimitations for protected areas., SI

The composition and structure of demersal chondrichthyan assemblages and the biological parameters of their main species were compared in four geographical subareas (GSAs) established by the General Fisheries Commission for the Mediterranean in the western Mediterranean : northern Alboran Sea (GSA01) and Alboran Island (GSA02), Balearic Islands (GSA05) and northern Spain (GSA06), with the first two being considered jointly. Data were obtained from 199 hauls undertaken from May to June 2013 during the Spanish International Bottom Trawl Survey in the Mediterranean (MEDITS). Twenty-five different chondrichthyan species were caught in all GSAs: seven were common to all areas, five appeared only in GSA01, nine appeared only in GSA05 and one appeared only in GSA06. Analysis of community structure (clusters, multidimensional scaling, analysis of similitude) revealed two assemblages related to depth, with very similar bathymetric ranges in all GSAs, namely continental shelf (from 41 to 252 m) and slope (from 284 to 813 m). The highest diversity, biomass and abundance values on the shelf and slope assemblages were recorded in GSA05 and GSA01 respectively. These results highlight the effects of the distinct fishing and oceanographic parameters related to the GSAs. Generally, the biological parameters of the most important species did not show differences between GSAs, which could suggest the existence of a single population in the western Mediterranean., SI

Resolving drivers of spatial synchrony in marine species is fundamental for the management and conservation of deep-sea ecosystems. Here we examine an 11-year data set of monthly catches per unit of effort (CPUE) of the red-shrimp Aristeus antennatus. These data comprise 16 locations of two population subunits in the Western Mediterranean, the Catalan coast and the Balearic archipelago. The analysis of their seasonal covariation and its space-time structure showed small-scale geographical segregation of locations linked with the seasonal fluctuations of CPUE. Results further revealed that seasonal synchrony dominates at short spatial scales (ca. 50 km), while asynchrony prevails are broader spatial scales (ca. 200-300 km). This spatial pattern, however, varied over the period examined, although it was specific for each population subunit suggesting contrasting drivers of seasonal synchrony. The Balearic Islands, a patchier population subunit, displayed a seasonal synchrony pattern mainly dependent on biological and oceanographic processes at local scales. By contrast, in the Catalan coast, the pattern appeared related with regional-scale climate, which triggers spatial differences in the phenology of primary producers and the timing of food advection to the seabed. These cascading processes depicted by our investigation shed light on underlying mechanisms shaping the temporal synchrony of broadly distributed deep-sea populations.

Special issue The wrapping up of the IDEADOS project: International Workshop on Environment, Ecosystems and Demersal Resources, and Fisheries.-- 10 pages, 5 figures, 3 tables, The structure and dynamics of cephalopod assemblages in different bathymetric strata from the surface to bottom grounds, down to a depth of 900. m, in the western Mediterranean, were analysed. Data were collected both on the shelf-break and slope during the summer and early autumn surveys, using a midwater trawl and a bottom trawl gear, to catch pelagic and nektobenthic species, respectively. The pelagic tows were not random, but targeted at the strongest and widest acoustic sound layers. A total of 26 cephalopod species belonging to 12 families were collected. With regard to the abundance, biomass and frequency of occurrence, we did not find a common seasonal trend for all the species, suggesting that their population dynamics are not governed by major environmental drivers. Most assemblage metrics (e.g., diversity, species richness, abundance and biomass) showed similar, low values in the pelagic layers compared to the bottom grounds. In general, assemblage metrics were lower in summer than in autumn on the shelf-break, while showing an inverse seasonal trend on the slope. There was a clear general increase in all metrics during the night compared to the day. Cluster results revealed differences in diel migratory strategies by stratum, vertical movements being scarce in the shelf-break species, but intense in the slope species. © 2013 Elsevier B.V.

12 pages, 4 figures, 6 tables, 1 annex, Epibenthic communities were studied in two areas, off western and southern Mallorca (Balearic Islands, western Mediterranean), which differ in the oceanographic conditions and show different degrees of oligotrophy. Sampling was performed with beam trawl at two seasons (December 2009 and July 2010) and at depths between 228 and 900. m. A total of 199 taxa were identified, of which the most diverse were decapod crustaceans and fishes. Depth was the main factor structuring megafaunal assemblages. In the shelf break the shrimps Plesionika heterocarpus, P. antigai, Processa nouveli and P. canaliculata were dominant. In the upper slope, P. acanthonotus, Boreomysis arctica, Gaidropsarus biscayensis and Aristeus antennatus were the species that most contributed to the group formation, whereas in the middle slope the crustaceans P. acanthonotus and Munida tenuimana dominated. Specific abundances were relatively low everywhere. Diversity H' values ranged from 2.19 to 3.17, being higher in Sóller. Using species abundance data, significant differences were identified concerning both area and season in both shelf break and upper slope strata, while no significant differences were found in the middle slope stratum. The analysis of functional groups showed that both depth and area had a significant effect on their differential distribution. © 2014 Elsevier B.V., Funding was provided by the IDEADOS project (CTM2008-04489-C03-01 and CTM2008-04489-C03-02)

A total of 648 dolphinfishes were examined for internal and external parasites in western Mediterranean (Balearic Islands) and central-eastern Atlantic (Canary Islands) waters in order to make a comparative study between the two areas. The specimens studied from the Mediterranean Sea was Coryphaena hippurus, with 62 large individuals captured from May to September and 497 juveniles captured from August to December. The specimens studied from the central-eastern Atlantic were 39 adult C. hippurus and 49 adult Coryphaena equiselis. Parasites were found in 70% of the fish examined, and represented a total of nine endoparasitic taxa: six digeneans (Class Trematoda, Subclass Digenea; Dinurus tornatus, Dinurus breviductus, Dinurus longisinus, Lecithocladium excisum, Bathycotyle branchialis and Hirudinella sp.), two nematodes (Class Nematoda, Order Spirurida; Philometroides sp. and Metabronema magna) and one acanthocephalan (Phyllum Acanthocephala; Rhadinorhynchus pristis). Seven crustacean copepod ectoparasites were identified: Caligus quadratus, Caligus productus, Caligus bonito, Caligus coryphaenae (Family Caligidae) and Euryphorus nymphae (Family Euriphoridae) were found in gill mucus masses or on the inner surface of the operculum, the lernaeopodid Neobrachiella coryphaenae (Family Lernaeopodidae) was attached to gill filaments and the pennellid Pennella filosa (Family Pennellidae) was anchored to fins and rays or, deeply, to muscular tissue and abdominal cavity. The relationships between feeding habits, parasite recruitment and parasite transmission were analysed, some ecological aspects of all the parasitic species are discussed, and some comments are made on parasite-host relationships.