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A Wisconsin type bioenergetics model was developed to investigate the growth and reproduction of the Mediterranean swordfish Xiphias gladius L., 1758. Reproduction was simulated using an energy allocation algorithm with a fixed part of assimilated energy stored for egg production. Stomach contents were used to estimate the daily ration of swordfish (3% of body weight for adults) in order to calibrate the consumption compartment. The model outputs of growth were in agreement with fisheries observation data, with estimates of annual egg production (~17.5 million eggs) per individual similar to those stemming from stock assessment datasets. Our study highlights the importance of bioenergetics in the reproduction of swordfish, suggesting that each individual is reproductively active for ~15 d, while the commonly reported spawning season of the whole population lasts ~90 d. Sensitivity analysis showed that swordfish growth and reproduction is largely controlled by consumption and respiration parameters. We provide a detailed description of a full life cycle swordfish bioenergetics model that could be embedded as a module in an end-to-end modelling framework, ultimately describing the population dynamics of the Mediterranean swordfish stock in relation to environmental variability.

The social ecological system (SES) framework is used to investigate the success of discard management, by gathering knowledge from worldwide examples of discard management applications. The literature search confirmed that most efforts aiming to reduce discards were implemented under top-down management schemes. For about half of the case studies where management tools were applied, a reduction of discards was achieved. To determine the attributes that influence the discard management success, a probabilistic classifier model (Naive Bayes Classifier) was used. This revealed that commonly used interventions to reduce discards can be ineffective unless advice is given in alternative forms that have societal acceptance. The role of social cohesion and stakeholder enforcement mechanisms is underlined and increases the odds of meeting successfully the recommendations for achieving sustainable fisheries. A successful combination of attributes that can lead to the minimization of discards requires robust social capital along with top-down measures. Overall, the classification algorithm proves the usefulness of the SES framework to describe the fishery response to managerial efforts that aim to reduce discarding. Establishment of links between fishing communities and scientists are the key for enhancing stakeholder engagement, increasing compliance and minimizing discards.

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.

Minimizing unwanted catches is a major milestone for achieving sustainable fisheries. In the framework of the Common Fisheries Policy, a landing obligation is being established progressively in European waters (Article 15, EU Regulation 1380/2013). Supplementary management measures have been proposed to support and enhance the effectiveness of this new regime. In this context, the effect of the landing obligation on a demersal mixed fishery (coastal and trawl fleet) in the Aegean Sea (NE Mediterranean Sea) was assessed in terms of both biological and economic sustainability. Our results show that the landing obligation alone does not ensure sustainable fisheries. Management action should be directed to the introduction of additional measures. Evidence suggests that improving selectivity and protecting the nursery grounds are possible solutions to decrease discards and ensure sustainable fisheries in the long term. The landing obligation can have a role in incentivizing the adoption of these management measures that ensure lower fishing mortality on juvenile fish., Minimizar las capturas no deseadas es un hito importante para lograr pesquerías sostenibles. En el marco de la Política Pesquera Común se está estableciendo progresivamente una obligación de desembarque en aguas europeas (artículo 15, reglamento 1380/2013 de la UE). Se han propuesto medidas de gestión complementarias para apoyar y mejorar la eficacia de este nuevo régimen. En este contexto, se evalúa el efecto de la obligación de desembarque en una pesquería mixta demersal (flota costera y de arrastre) en el mar Egeo (NE mar Mediterráneo), tanto en términos de sostenibilidad biológica como económica. Nuestros resultados muestran que la obligación de desembarque por sí sola no garantiza una pesca sostenible, y que la gestión debería enfocarse hacia la introducción de medidas adicionales. Las evidencias obtenidas sugieren que mejorar la selectividad de las artes de pesca y proteger las áreas de alevinaje son dos soluciones posibles para disminuir los descartes y garantizar una pesca sostenible a largo plazo. La obligación de desembarque puede tener un papel en incentivar la adopción de estas medidas de gestión, que aseguran una menor mortalidad por pesca en peces juveniles.

Management of mixed fisheries requires reconciling many different and often conflicting objectives (achieving MSY targets and ensuring economic viability among others). In multi-gear mixed fisheries, where many fleets exploit the same species, reallocation of fishing effort can optimize the biological and socioeconomic output of the fishery. Most existing effort allocation tools require extensive data for their parameterization (i.e. detailed effort data and/or analytical assessment of stock status). We present a low-data demanding effort allocation framework for fisheries managed through effort control, with minimum data requirements the surplus production assessment of key stock, catch shares and basic economic fleet data. Profit maximization is considered the overall management goal, which is constrained by single-species biological targets. The method is tested on the Aegean Sea demersal fishery, where two fleet segments exploit numerous species. To achieve sustainable exploitation for the main Aegean stocks, the total effort should be reduced by ∼30%. The framework allows integrating various biological, economic, or other objectives and provides a simple graphical illustration of the allocation result, which can provide a useful tool to convey complex information to managers. To facilitate its application, the source code developed in R programming environment is provided as a supplement.

15 pages, 6 figures, 4 tables, supplementary data https://doi.org/10.1016/j.fishres.2020.105714, Discards is an important issue in fisheries around the world. The spatial management of discards has attracted interest as a potential tool for minimizing the unwanted catch. The aim of the present work was to identify areas with high quantities of bottom trawl discarded catch regarding species subjected to MCRS, in six areas of southern European waters (southern Portuguese waters, Catalan Sea, Ligurian and northern Tyrrhenian Seas, Strait of Sicily, eastern Ionian Sea, and Aegean Sea). Analyses were based on two types of data: (a) the undersized catch of species subjected to MCRS from bottom trawl surveys and (b) the actual discarded catch (including undersized and non-undersized individuals) of species subjected to MCRS from commercial bottom trawling. Geostatistical analysis techniques were applied to the first type of data and Generalized Additive Models using environmental variables were applied to the second one. Subsequently, areas that persistently presented high quantities of discarded catch (i.e., “iDC grounds”) or undersized catch (i.e., “iUC grounds”) were identified and mapped. The “iDC grounds”/“iUC grounds” were located either over the slope or within the continental shelf and over marine plateaus, largely depending on the main target species of each fishery. Next, the overlap of “iDC grounds”/“iUC grounds” with the existing Fisheries Restricted Areas (FRAs) and the proposed Marine Protected Areas (MPAs) was estimated aiming to explore how spatial closures could contribute to the reduction of bottom trawl discarded catch/undersized catch. Certain spatial closures were more effective in the Central Mediterranean and others to the Eastern Mediterranean. The overlapping of existing FRAs with “iDC grounds”/“iUC grounds” did not exceed 24 % in any study area, whereas proposed MPAs, like the CIESM Marine Peace Parks, reached up to 90 % for the same study area, This work was funded by the European Commission’s Horizon 2020 Research and Innovation Program under Grant Agreement No. 634495 for the project Science, Technology, and Society Initiative to minimize Unwanted Catches in European Fisheries (MINOUW). We thank people involved in the MEDISEH project (MAREA PROJECT MEDISEH: Mediterranean Sensitive Habitats, Specific Contract No 2, SI2.600741) for data provision regarding FRAs and MPAs, With the funding support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S), of the Spanish Research Agency (AEI)

Swordfish (Xiphias gladius) is heavily exploited in the Atlantic Ocean by several European fleets and age and growth studies are essential for the accomplishment of the stock assessments carried out by ICCAT. The present study aims to validate the periodicity of growth increments on swordfish fin spines and provide first estimates of the growth parameters of South Atlantic swordfish. A total of 502 (231 males and 271 females) spine samples were collected from swordfish specimens onboard commercial longline vessels, from 2006 to 2009. Estimated ages ranged between 0 and 12 years, with age groups 3 and 4 dominating the samples. Marginal increment analysis suggested that growth bands were deposited annually in mid-spring. Fitted standard von Bertalanffy growth parameters (sexes combined) were L∞ = 317.133, k = 0.085 and t0 = −2.488. Minor, but insignificant, growth differences were observed between sexes.

The present study provides updated information on the occurrence, abundance and biomass distribution patterns and length frequencies of Merluccius merluccius in the Mediterranean Sea, by analysing a time series of data from the Mediterranean International Trawl Surveys (MEDITS) from 1994 to 2015. The highest values of abundance and biomass were observed in the Sardinian Seas. The use of a generalized additive model, in which standardized biomass indices (kg km–2) were analysed as a function of environmental variables, explained how ecological factors could affect the spatio-temporal distribution of European hake biomass in the basin. High biomass levels predicted by the model were observed especially at 200 m depth and between 14°C and 18°C, highlighting the preference of the species for colder waters. A strong reduction of biomass was observed since the year 2009, probably due to the strengthening of the seasonal thermocline that had greatly reduced the availability of food. The general decrease in biomass of several stocks of anchovy and sardine, preys of European hake, might be indirectly connected to the decreasing biomass detected in the present study. The length analysis shows median values lower than 200 mm total length of most of the investigated areas.

Chondrichthyan species are considered highly susceptible to fishing activities and as “indicator species” for overfishing and ecosystem stability. In European waters, chondrichthyes have become a focus of conservation actions due to the abundance declines of several species. In the present study, fishery independent data obtained from the Mediterranean International Trawl Surveys (MEDITS) in the Aegean and E. Ionian Seas (eastern Mediterranean) were coupled with bottom trawl fishing effort data obtained from vessel monitoring systems (VMS) in order to evaluate the effect of fishing on biomass variations of demersal chondrichthyan species. The study focused on commonly captured species such as Raja clavata, Galeus melastomus, Scyliorhinus canicula and Squalus spp, as well as to the total chondrichthyan biomass. The effect of fishing effort on biomass indices, expressed in terms of kg per square km of swept area, was examined by means of Generalized Additive Model techniques, using also the sampling position, year and depth as co-variates. Overall findings suggested a biomass decline of chondrichthyan species with increasing fishing effort. Nevertheless, it was also found that certain species (e.g G. melastomus in both areas and S. canicula in the Aegean Sea) can withstand fishing pressure and it is likely that discard survival rates, depth preferences and fisheries exploitation patterns, are the main drivers explaining variations regarding the impact of fishing on the different stocks.

WOS: 000455910400001, Background. The swordfish,Xiphias gladius Linnaeus, 1758, is a pelagic and highly migratory species distributed in the Atlantic, Indian, and Pacific oceans as well as in the Mediterranean Sea. Swordfish fishing has been carried out in the Mediterranean with longlines, gillnets, harpoons, and traps since the Roman times. Although information is available on the influence of the lunar phase on the catch per unit effort (CPUE) for the swordfish longline fishery in the Atlantic and Pacific oceans, the data concerning the Mediterranean is rather limited. The aim of this study was to examine the relation between the lunar phase and the swordfish CPUE, based on data from Turkish longline fisheries, targeting swordfish in the eastern Mediterranean during the 2008-2016 fishing seasons. Material and methods. We monitored randomly the daily fishing activity of longliners based at the ports of Fethiye and (Dzdere during 2008-2016. A total of 86 surveying operations were carried out, including 79 in the area between Fethiye and Alanya, the remaining ones were in Ozdcre in the southern Aegean coasts along the eastern Mediterranean Sea. The effect of the lunar phase on the swordfish catch rates, expressed in terms of kg . 1000 hooks(-1), was examined by means of the Generalized Additive Modelling (GAMS) techniques. Results. The observed CPUE rates ranged from 0 to 700 kg . 1000 hooks(-1). The mean swordfish CPUEs in the dark and light periods of the lunar cycle were equal to 178.10 +/- 19.01 and 175.27 +/- 19.56 kg . 1000 hooks(-1), respectively. Although no significant differences among phases of the Moon were found (P > 0.05), CPUEs differed significantly between years (P < 0.05). Conclusion. It seems that the mechanism linking swordfish CPUE variations with the lunar cycle involves several factors, making difficult the identification of direct relations. Further studies are needed to better clarify the impact of the lunar phase on the longline gear, considering also additional parameters, such as light transition, prey abundance, physico-chemical characteristics of the marine environment, and the soak time of the gear., Turkish Scientific and Technological Research Council (TUBITAK)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [108O210]; Ege University Science and Technology Center (EBILTEM Project)Ege University [2009/BIL/019], This study was funded by the Turkish Scientific and Technological Research Council (TUBITAK Project No. 108O210) and the Ege University Science and Technology Center (EBILTEM Project No. 2009/BIL/019). We also thank skippers of swordfish fishing boats for giving us the opportunity to work freely on board.

International audience; Cephalopod assemblages at the scale of the entire Mediterranean Sea were analysed using information from 2 decades of standardized scientific bottom trawl surveys. Western and eastern assemblages (6 yr of data) were compared using a combined approach of multivariate ordination techniques and non-linear regressions. These methods enabled us to distinguish assemblages and simultaneously analyse the influence of geographic, bathymetric and environmental (sea surface temperature and chlorophyll a concentration) gradients on observed community patterns. Despite few differences in species composition between sub-basins, the relative contribution of species differed. Bathymetry was the primary structural driver for the cephalopod communities of both basins, and contributed to 3 assemblages (shallow water, upper slope and middle slope). Winter temperature influenced community assemblages more strongly in the western than in the eastern basin, in contrast to a small but consistent winter productivity influence on community assemblages in both basins. Thus, the environmental parameters analysed did not cause an immediate change in cephalopod assemblages, but rather an effect lagged by several months. Differences in the relative importance of environmental drivers show that different processes operate in the 2 basins. These results demonstrate similarities and differences between Mediterranean basins regarding important cephalopod functional groups. This information should help integrative ecosystem management approaches currently used in fisheries and conservation management.

The Mediterranean Sea is characterized by large scale gradients of temperature, productivity and salinity, in addition to pronounced mesoscale differences. Such a heterogeneous system is expected to shape the population dynamics of marine species. On the other hand, prevailing environmental and climatic conditions at whole basin scale may force spatially distant populations to fluctuate in synchrony. Cephalopods are excellent case studies to test these hypotheses owing to their high sensitivity to environmental conditions. Data of two cephalopod species with contrasting life histories (benthic octopus vs nectobenthic squid), obtained from scientific surveys carried out throughout the Mediterranean during the last 20 years were analyzed. The objectives of this study and the methods used to achieve them (in parentheses) were: (i) to investigate synchronies in spatially separated populations (decorrelation analysis); (ii) detect underlying common abundance trends over distant regions (dynamic factor analysis, DFA); and (iii) analyse putative influences of key environmental drivers such as productivity and sea surface temperature on the population dynamics at regional scale (general linear models, GLM). In accordance with their contrasting spatial mobility, the distance from where synchrony could no longer be detected (decorrelation scale) was higher in squid than in octopus (349 vs 217 km); for comparison, the maximum distance between locations was 2620 km. The DFA revealed a general increasing trend in the abundance of both species in most areas, which agrees with the already reported worldwide proliferation of cephalopods. DFA results also showed that population dynamics are more similar in the eastern than in the western Mediterranean basin. According to the GLM models, cephalopod populations were negatively affected by productivity, which would be explained by an increase of competition and predation by fishes. While warmer years coincided with declining octopus numbers, areas of high sea surface temperature showed higher densities of squid. Our results are relevant for regional fisheries management and demonstrate that the regionalisation objectives envisaged under the new Common Fishery Policy may not be adequate for Mediterranean cephalopod stocks., SI

Regional fisheries management organizations (RFMO) are often criticized for ineffectual management of high-seas fisheries resources. However, in the case of the two Atlantic swordfish stocks occurring in the North and South Atlantic, those stocks have rebuilt to the BMSY objective of the responsible RFMO, the International Commission for the Conservation of Atlantic Tunas (ICCAT). The relative contribution of the management actions of the RFMO and biological characteristics of swordfish stocks are evaluated in relation to the recovery of the stocks. It is concluded that while swordfish have characteristics that promote stock resilience (including relatively fast growth, and spatially- and temporally-dispersed spawning), positive management actions combined with a period of relatively good recruitment were essential to achieve the rebuilt outcome. The challenges that the RFMO faces to maintain the stocks in the rebuilt condition are described, and some possible additional measures discussed.

A time series of data for the demersal elasmobranchs Mustelus mustelus, Raja asterias, Torpedo marmorata and Galeus melastomus obtained from the “MEDITS” experimental surveys carried out in the Aegean Sea from 1998 to 2008 were examined to identify depth preferences, together with the spatial and temporal distribution pattern of the species. Survey data have been modelled by means of Generalized Additive Models (GAMs), as functions of depth, sampling position (latitude–longitude interaction) and year. Both depth and geographical coordinates were the key determinants of the presence of all species, while annual abundance fluctuations were found to be either insignificant or without any specific trend. The depth distribution patterns differed between species. M. mustelus, and T. marmorata, were more frequent in continental shelf areas (up to 180–200 m). R. asterias preferred the transitional depth zone between shelf and slope (around 200 m), while depths over 350 m (continental slope) favoured the presence of G. melastomus. Model predictions were used to generate density distributions maps, which could facilitate conservation plans in the area through the identification of abundance hotspots.

International audience; Functional groups are sets of species that play a similar role in a food web. We defined functional groups of fish species based on their morphological characteristics, while using expert knowledge for invertebrates. We measured 9 morphological traits of 72 fish species, and carried out multivariate analyses to assign fish species to functional groups. The analysis identified 9 trait-based fish functional groups to which were added 3 expert-based invertebrate functional groups. The habitat (position in the water column) and potential diet of each group were identified from the literature. Using the MEDITS bottom trawl survey data collected at 10 to 800 m depth, we calculated relative change in the 12 fish and invertebrate functional group biomasses for 12 Mediterranean areas over the period 1994 to 2012. Multiple regression trees identified 4 regions with similar changes: (1) the Adriatic and the Ionian Sea; (2) the Tyrrhenian Sea and the Strait of Sicily; (3) the Balearic Islands and other enclosed areas such as the Gulf of Lions and Aegean Sea; and (4) the Ligurian Sea and Sardinia. The biomass of all functional groups increased or remained stable in the first 2 regions, while around half the functional group biomasses decreased in the other 2 regions. These regional differences in functional group biomass changes were mainly associated with regional variations in the time trends of bottom water temperature (37%), bottom water dissolved oxygen (23%) and mean catch levels (9%). This study contributes to the EU Marine Strategy Framework Directive by proposing food web indicators based on morphologically and habitat defined functional groups.

A time series of survey abundance indices for commercially important demersal fish and cephalopod species, inhabiting the narrow continental shelf of the southern Aegean Sea, is analyzed in relation to the topography of the area in order to evaluate the impact of different spatial fishery bans on the bottom-trawl fishery. With reference to the current situation, results suggested that implementation of the 1967/2006 EC Regulation, which bans bottom-trawl activities within 1.5 NM off the coast, will significantly increase (20–80%, depending on the species) the proportion of the populations that are inaccessible to the bottom-trawl fishery. It might also result in shifting of fishing activities toward deeper waters, adding fishing pressure onto slope resources inhabiting the slope. As depth determines, to a large extent, the distribution pattern of the species, it constitutes a variable of crucial importance for the spatial management of marine fisheries and should be taken into account when adopting relevant management regimes.

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 development of ecosystem approaches to environmental management implies the need to account for multiple pressures on ecosystems. Trends in multiple metrics that respond differently to changes in major environmental pressures need to be combined to evaluate the impacts of fishing and environmental changes on fish communities. 2. An exploited fish community is viewed as a three-level food chain in which the two upper levels, or functional groups, are targeted by fishing fleets, while the lowest level is subject to environmental variation. Qualitative modelling is used to predict changes at the two upper levels, that is, top-down vs. bottom-up perturbations. Abundance and length metrics are calculated from survey data for 14 Mediterranean and East-Atlantic groundfish shelf communities at both population and functional group levels. The joint likelihood of time trends in metrics is used to evaluate the evidence for different causes of changes. 3. A wide diversity of impacts is found to have equal evidence at the population level within each community. Consistency between the impacts identified and changes in pressures known from independent information is found at the functional group and community level. The results suggest that there is some compensation between species within functional groups. 4. Synthesis and applications. The method can be used to conduct an integrated assessment of community dynamics subject to multiple pressures. Joint trends in metrics provide evidence of which known pressures are having an impact on the community, and thus, which management actions should be taken to mitigate these changes.

The biological and economic implications of different management measures concerning the Mediterranean swordfish stock were evaluated by means of simulations performed under the Fisheries Language in R (FLR) framework. Six different scenarios were examined including Mediterranean-wide seasonal closures of different duration and an effort reduction scheme. Recruitment was assumed to vary in levels either predicted by a Beverton–Holt stock–recruitment relationship or around an average value estimated from the latest assessment accomplished by the International Commission for the Conservation of Atlantic Tunas (ICCAT). Simulations projected the levels of landings, spawning stock biomass (SSB), gross and net revenue for a period of twenty years. Considering the estimated statistical uncertainty, gains in terms of landings and SSB from short fishery closures (e.g. one month) will be negligible. On the contrary, seasonal closures of at least four months would result in important long-term gains, which are more profound in the case of SSB and net revenue. The ICCAT convention objectives concerning SSB, can only be met with drastic closures (i.e. six months). However, drastic closures would result in short-term decreases in landings and revenues, which should be taken into account before such measures are adopted.

Fisheries management in the Mediterranean is planned on the basis of fishing effort allocation, gear technical characteristics and minimum landing sizes (MLSs), the latter being a measure recently updated in the EU Mediterranean fisheries policy. Very few elements on the evaluation of the MLS in regard to the catch and landings of the small-scale fisheries in the Mediterranean exist and this is due to both the great heterogeneity of the sector and the lack of systematic monitoring. The catch length composition of five species ( Merluccius merluccius , Diplodus annularis , Mullus barbatus , Sepia officinalis and Squilla mantis ) from a yearly record of small-scale fishing operations in the Patraikos Gulf (w. Greece, e. Mediterranean) was associated with temporal (season), spatial (depth of fishing, substrate type) and fishery (metier) characteristics by means of general linear models. Smaller individuals appeared in the catch in autumn for all five species indicating this season as suitable if a seasonal fishery closure was established. When length was found to be significantly different between different metiers this was either due to smaller mesh sizes ( M. barbatus ) or due to gear type ( M. merluccius ). For all species except S. officinalis , depth significantly affected length of individuals in the catch providing in the case of M. merluccius a clear association of bigger individuals with deeper fishing grounds. Substrate types also affected the length for the species D. annularis , M. barbatus . In relation to MLSs, the sizes of Mullus surmuletus and Scomber japonicus were fully legal, M. merluccius , M. barbatus , Solea vulgaris , Trachurus mediterraneus , Pagellus erythrinus had higher than 80% of the catch over MLS, while D. annularis , Diplodus sargus , Sparus aurata and Pagellus acarne had high fractions of the total catch below MLS. The metiers where undersized individuals appear were identified. Further management implications of the findings are discussed taking into account the current management scheme and the discarding practices in the area.

A time series of hake abundance data obtained from the “MEDITS” experimental surveys carried out in the Greek seas from 1996 to 2006 have been modeled by means of Generalized Additive Models (GAMs), as functions of spatial and temporal variables, including sampling position (latitude–longitude interaction), depth, and year. All variables were highly significant but most of the variation was explained by the sampling position and the depth. Total abundance was higher in the 100–450 m depth zone, while juveniles showed preference for shallower waters, being more abundant from 100 to 320 m. Model predictions were used to generate density distributions maps, which revealed that total abundance is relatively higher in the western part of the Aegean Sea and in the eastern part of the Cretan Sea, while its maximum values are expected in the Saronikos Gulf. Nursery grounds are restricted in specific regions with the most important of them being in the Saronikos Gulf and its surrounding area.

Generalized Additive Modelling (GAM) techniques were used to model the time series of abundance data of deep-water pink shrimp, collected during the MEDITS bottom trawl surveys carried out in the Greek seas from 1996 to 2006, as functions of the sampling location (longitude-latitude), depth and year. The life stages of the species were taken into account. All variables were highly significant, although latitude and depth had always the highest explanatory power. The total abundance was higher between 100 and 400 m of depth, with juveniles and adults being more abundant in the 100-200 m and 200-400 m depth strata, respectively. GAM predic- tion maps showed high abundance concentration areas for all life stages mainly in the Aegean Sea. The most important nursery ground identified was located in the Saronikos Gulf and a secondary in the Thracian Sea. Concerning the concentration areas of the adult specimens, they are located mainly in the Saronikos Gulf, the Thracian Sea, the Thermaikos Gulf, the Cretan Sea and the eastern part of the Aegean.

Swordfish catch per unit effort (CPUE) data from the Greek commercial fisheries operating in the eastern Mediterranean have been modeled on a seasonal basis as functions of environmental spatial, and temporal variables, including Sea Surface Temperature (SST), Chlorophyll-a (Chl-a), Mean Sea Level Anomaly (MSLA), Latitude, Longitude and Year. All variables were highly significant but most of the CPUE variation was explained by the spatial factors. Model predictions were used to generate swordfish density distributions maps, which revealed that swordfish migrates toward the eastern Levantine for spawning and suggested the existence of a major spawning ground in a region between the islands of Cyprus and Rhodes surrounded by persistent eddies and the Rhodes gyre. During periods other than the time of spawning migration, swordfish distribution is much broader with relatively higher concentrations occurring in areas with important prey potential.

Discarding practices from 110 fishing operations in a Mediterranean small-scale fishing fleet (Patraikos Gulf, western Greece) from August 2004 to July 2005 were analysed. On average, 1 kg of fish was discarded per fishing operation (10% of the catch). The reasons for discarding were: low commercial value (78% of discards), damage at sea before retrieval of the gear (5%), and bad handling on-board (17%). More than half of discards belonged to Spicara flexuosa (L.), Lepidopus caudatus (Euphrasen), Sardinella aurita Valenciennes and Merluccius merluccius (L.). The bulk of discards of each species were associated with a single fishing method (metier). A Generalized Linear Model (Delta-X – error-model) indicated that, when discards were present, significant differences existed in the discard ratio among different metier groups (groups comprising metiers with similar characteristics). Longlines and trammel nets with small mesh-sizes had the highest discard ratios. Discarding practices for the species Diplodus annularis (L.), S. aurita, Squilla mantis (L.), S. flexuosa and Scorpaena scrofa (L.) did not follow a consistent pattern (these species were either fully discarded or fully retained during a fishing operation). The decision seemed to be dependent on market demands rather than fish size. Significant correlation was found between discarded and catch weight, but the presence of many outliers indicated deviance from a case where discards are high when there is an abundant catch. The findings of the study imply that monitoring and management should be carried out preferably on the metier level. Discards could be reduced by technical measures, controlling effort regulations and by improving working conditions on-board fishing vessels.

The identification of nursery grounds and other essential fish habitats of exploited stocks is a key requirement for the development of spatial conservation planning aimed at reducing the adverse impact of fishing on the exploited populations and ecosystems. The reduction in juvenile mortality is particularly relevant in the Mediterranean and is considered as one of the main prerequisites for the future sustainability of trawl fisheries. The distribution of nursery areas of 11 important commercial species of demersal fish and shellfish was analysed in the European Union Mediterranean waters using time series of bottom trawl survey data with the aim of identifying the most persistent recruitment areas. A high interspecific spatial overlap between nursery areas was mainly found along the shelf break of many different sectors of the Northern Mediterranean indicating a high potential for the implementation of conservation measures. Overlap of the nursery grounds with existing spatial fisheries management measures and trawl fisheries restricted areas was also investigated. Spatial analyses revealed considerable variation depending on species and associated habitat/depth preferences with increased protection seen in coastal nurseries and minimal protection seen for deeper nurseries (e.g. Parapenaeus longirostris 6%). This is partly attributed to existing environmental policy instruments (e.g. Habitats Directive and Mediterranean Regulation EC 1967/2006) aiming at minimising impacts on coastal priority habitats such as seagrass, coralligenous and maerl beds. The new knowledge on the distribution and persistence of demersal nurseries provided in this study can support the application of spatial conservation measures, such as the designation of no-take Marine Protected Areas in EU Mediterranean waters and their inclusion in a conservation network. The establishment of no-take zones will be consistent with the objectives of the Common Fisheries Policy applying the ecosystem approach to fisheries management and with the requirements of the Marine Strategy Framework Directive to maintain or achieve seafloor integrity and good environmental status., This study was supported and financed by the Commission of the European Union (DG MARE) through the Project MEDISEH: Mediterranean Sensitive Habitats within the MAREA Framework contract (Call for tenders MAREA/2009/05). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript., peer-reviewed

An ecological niche modelling (ENM) approach was developed to model the suitable habitat for the 0-group European hake, Merluccius merluccius L., 1758, in the Mediterranean Sea. The ENM was built combining knowledge on biological traits of hake recruits (e.g. growth, settlement, mobility and feeding strategy) with patterns of selected ecological variables (chlorophyll-a fronts and concentration, bottom depth, sea bottom current and temperature) to highlight favourable nursery habitats. The results show that hake nurseries require stable bottom temperature (11.8–15.0 °C), low bottom currents (, peer-reviewed

The main metiers practiced by small-scale fishermen in the Patraikos Gulf (western Greece, E. Mediterranean) were identified using data from 144 fishing operations carried out from August 2004 to July 2005. These operations were categorized by gear and subsequently classified hierarchically, based on target species declared by the skippers before the fishing operation. A total of 12 metiers was defined in terms of fishing gear, target species and season. Two metiers were active throughout the year whereas the remainder showed a more or less seasonal pattern of activity. The metiers differed significantly with regard to catch composition, production and income (all P

We analyzed fisheries data collected in 2000 and 2001 from the Greek swordfish fishing fleets operating in the eastern Mediterranean, by means of machine-learning approaches, in order to define differences in exploitation patterns and fishing strategies. Based on their total annual catch, fishing vessels have been classified in three groups: low, medium and high producers. Decision-tree analysis revealed that group membership could be successfully predicted from the total number of working days per year, the vessel length, the type of gear used, the hook size and the number of hooks per set. Using the data of 2001 as a test data set and assuming that only the average catch of the most productive group was known, total production estimates for that year showed very little difference (7.92%) from the true values. These findings indicate that simple sampling schemes focusing on the high producers may be adequate for the examined fisheries. They also provide evidence that such methodological approaches could be useful for the cross-checking of fisheries estimates obtained through various sampling schemes.

The composition of the opaque and translucent bands in the otoliths of European hake (Merluccius merluccius) from three different populations (Celtic Sea, Galicia shelf and Cretan Sea) was analysed with wavelength dispersive spectrometry (WDS) and differences in Ca, Sr and Na were compared. The translucent bands (annual marks and checks altogether) were significantly richer in Sr and Ca and significantly poorer in Na than opaque bands. Results support the idea of a more compact arrangement of crystals in translucent bands compared to opaque. Analyses did not help to discriminate between putative annual marks and checks. Clear differences in the range of Sr/Ca variation across the otolith as well as in the composition of the otolith core were observed among the three populations. As a result it was possible to discriminate the natal origin of each fish using the composition of the otolith core in Ca, Sr and Na. Nevertheless, the overall pattern across the otolith was similar among the three populations suggesting the existence of ontogenetic trends. Variation of Na/Ca ratios was largely uninformative. Based on these results, a conceptual model for hake is proposed which integrates the different sources of otolith Sr/Ca variation: ambient Sr/Ca, endogenous cues (ontogeny) and exogenous cues (environment). 2