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21 pages, 8 figures, 1 table, supporting information https://doi.org/10.1111/mec.16840.-- Data Availability Statement: Raw reads have been deposited to European Nucleotide Archive (ENA) under the accession id PRJEB45992. A VCF file with all filtered and unlinked SNPs used in the analyses of this study is provided as an additional file., By evaluating genetic variation across the entire genome, one can address existing questions in a novel way while raising new ones. The latter includes how different local environments influence adaptive and neutral genomic variation within and among populations, providing insights into local adaptation of natural populations and their responses to global change. Here, under a seascape genomic approach, ddRAD data of 4609 single nucleotide polymorphisms (SNPs) from 398 sardines (Sardina pilchardus) collected in 11 Mediterranean and one Atlantic site were generated. These were used along with oceanographic and ecological information to detect signals of adaptive divergence with gene flow across environmental gradients. The studied sardines constitute two clusters (FST = 0.07), a pattern attributed to outlier loci, highlighting putative local adaptation. The trend in the number of days with sea surface temperature above 19°C, a critical threshold for successful sardine spawning, was crucial at all levels of population structuring with implications on the species' key biological processes. Outliers link candidate SNPs to the region's environmental heterogeneity. Our findings provide evidence for a dynamic equilibrium in which population structure is maintained by physical and ecological factors under the opposing influences of migration and selection. This dynamic in a natural system warrants continuous monitoring under a seascape genomic approach that might benefit from a temporal and more detailed spatial dimension. Our results may contribute to complementary studies aimed at providing deeper insights into the mechanistic processes underlying population structuring. Those are key to understanding and predicting future changes and responses of this highly exploited species in the face of climate change, This study was carried out within the European Research Contract SPELMED (EASME/EMFF/2016/032) funded by the Executive Agency for Small- and Medium-sized Enterprises (EASME) of the European Commission (DGMARE). [...]. MC would like to acknowledge partial funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No. 869300 (FutureMARES). MC and FR acknowledge the institutional support of the “Severo Ochoa Centre of Excellence” accreditation (CEX2019-000928-S). FR was supported by the Ramón y Cajal programme (Spanish Ministerio de Ciencia e Innovación, RYC2020-030078-I). This research was supported in part through computational resources provided by IMBBC (Institute of Marine Biology, Biotechnology and Aquaculture) of the HCMR (Hellenic Centre for Marine Research). Funding for establishing the IMBBC HPC has been received from the MARBIGEN (EU Regpot) project, LifeWatchGreece RI and the CMBR (Centre for the study and sustainable exploitation of Marine Biological Resources) RI, implemented under the Action “Reinforcement of the Research and Innovation Infrastructure,” funded by the Operational Programme “Competitiveness, Entrepreneurship and Innovation” (NSRF 2014-2020) and cofinanced by Greece and the European Union (European Regional Development Fund)

The presence of plastic waste in the marine environment has driven the scientific community to make significant efforts to study and mitigate its possible effects. One of the critical aspects is to determine if and how an increase in ingestion events may occur as a result of the accumulation of plastic waste on the seabed. In this study, G. melastomus is examined for its ability to indirectly provide information on the amount of macroplastics accumulating on the seafloor. Plastic ingestion is explored by describing the feeding habits of the species, which have the potential to provide very useful information regarding biological or ecological issues. The diet of G. melastomus mainly consisted of cephalopods, bathypelagic fishes, and decapod crustaceans, increasing in diversity during growth. The generalist-opportunistic feeding behaviour of this species leads to the incidental ingestion of plastic particles (N = 47, with a mean (± SD) of 1.47 ± 0.28 per specimen) which can be indirectly associated to the presence of macroplastics on the seafloor. Indeed, our results indicate a significant relationship between the amount of macroplastics present on the seabed and the frequency of ingestion of plastic particles by blackmouth catshark. We propose G. melastomus as an excellent candidate for developing a valid monitoring strategy for the presence of plastics on the seabed, as requested by the EU Marine Strategy Framework Directive.

The main characteristics concerning the distribution of two of the most important decapod crustaceans of commercial interest in the Mediterranean Sea, the deep-water rose shrimp, Parapenaeus longirostris, and the Norway lobster, Nephrops norvegicus, are studied in the European Mediterranean waters. The study is based on data collected under the MEDITS trawl surveys from 1994 to 2015 from the Gibraltar Straits to the northeastern Levantine Basin (Cyprus waters). The observed differences can be interpreted as different responses to environmental drivers related to the differing life history traits of the two species. In fact, N. norvegicus is a long-living, benthic burrowing species with low growth and mortality rates, while P. longirostris is an epibenthic, short-living species characterized by higher rates of growth and mortality, Se investigaron las características de la distribución de dos de los crustáceos decápodos más importantes a nivel comercial del mar Mediterráneo, la gamba de altura, Parapenaeus longirostris y la cigala, Nephrops norvegicus, en aguas mediterráneas europeas. El presente estudio se basa en datos recopilados en las campañas de pesca experimental de arrastre MEDITS, relizadas de 1994 a 2015 desde el estrecho de Gibraltar hasta la cuenca levantina nororiental (aguas de Chipre). Las diferencias observadas en el patrón de distribución se pueden interpretar como distintas respuestas a factores ambientales relacionados con los diferentes rasgos del ciclo vital de las dos especies. De hecho, N. norvegicus es una especie bentónica de vida larga, con bajas tasas de crecimiento y mortalidad, mientras que P. longirostris es una especie epibentónica de vida corta, caracterizada por tasas más altas de crecimiento y de mortalidad

There is currently very little information on the survival of discards of unwanted and unregulated catches of invertebrates after the stresses caused by capture. A great number of the unregulated invertebrate species form the basis of essential fish habitats for important fisheries resources such as hake, red mullet and cuttlefish. Thus, data on their survival after discarding may help to interpret the role of these species within the benthic ecosystems. Furthermore, descriptor 6 of the Marine Strategy Framework Directive (EU Directive 2008/56/E) foresees maintaining sea floor integrity at a level that ensures that the structure and functions of the ecosystems are safeguarded, and Article 7(d) of the Common Fisheries Policy (EU Reg. 1380/2013) foresees the implementation of management measures for fishing with low impact on the marine ecosystem and fishery resources. Survival measurements by direct recovery of tagged discarded species are not effective in bottom trawl fisheries, for which alternative studies such as semi-quantitative measures obtained on board prior to discarding can be considered as appropriate for mortality estimation. The present work assessed the survival of unwanted species using a semi-quantitative assessment on the deck of trawlers and at the laboratory for a period of 96 hours in two Mediterranean areas (the Catalan coast and the Ligurian and Northern Tyrrhenian seas). A high number of discarded invertebrates showed a high percentage of survival (>70%) in both assessments. The results can be used to provide information that can help to achieve higher survival levels of discarded specimens and enhance the productivity of fishing grounds by increasing the health of benthic ecosystems. Actualmente, hay muy poca información sobre la supervivencia del descarte de los invertebrados no-deseados y no-regulados después del stress de la captura. Un gran número de especies de estos invertebrados son básicas para los hábitats esenciales de importantes recursos pesqueros como la merluza, el salmonete o la sepia. Por lo tanto, información sobre su supervivencia al ser descartados pueden ayudar a interpretar el papel de estas especies dentro de los ecosistemas bentónicos. Además, el punto 6 de la Directiva Marco de Estrategia Marina (MSFD, EU Directive 2008/56/E) prevé mantener la integridad del fondo marino a un nivel que garantice la protección de la estructura y de las funciones de los ecosistemas, y el artículo 7 (d) de la Política Pesquera Común (PPC EU Reg. 1380/2013) prevé la implementación de medidas de gestión para la pesca, que tengan bajo impacto tanto en el ecosistema marino como en los recursos pesqueros. En el caso de las pescas de arrastre de fondo, no es efectiva la estimación de la supervivencia a partir del método directo de captura-recapture de las especies del descarte marcadas, por lo que los estudios alternativos, como las medidas semicuantitativas obtenidas a bordo antes del descarte, pueden considerarse una estimación de la mortalidad apropiada. El presente trabajo evaluó la supervivencia del descarte de especies no-deseadas utilizando una Evaluación Semicuantitativa (SQA) mediante dos estudios: uno sobre la cubierta de los arrastreros y el otro en laboratorio durante un período de 96 horas, en dos áreas del Mediterráneo, las costas Catalanas y en los mares de Liguria y del Tirreno Norte. Los resultados mostraron en ambos estudios, que un alto número de invertebrados descartados tenía un alto porcentaje de supervivencia (>70%). El propósito de estos resultados es proporcionar información que puede ayudar a alcanzar niveles de supervivencia más altos de los individuos descartados. Al mismo tiempo, se espera que con esta mejora se consiga potenciar la productividad de los caladeros al aumentar la salud de los ecosistemas bentónicos.

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)

Small-scale fisheries represent one of the most important fishing sectors in Italy, comprising 60% of Italian fishing vessels, half the fishers and 16% of national landings. Despite their high social, economic and cultural value, they have been neglected by national and international policies, resulting in a poor outlook for the near future. In this chapter, we provide an overview of recent trends, the status of small-scale fisheries in Italy and major, current threats to the sector. These include: competition from large-scale fisheries, rivalry with illegal, unreported and unregulated fishing, recreational fisheries, ecological changes and the degradation of ecosystems. The evolution of international and national legislation affecting small-scale fisheries is also outlined, with examples of opportunities and challenges in two complementary case studies from the Tyrrhenian and Ionian Seas. The analysis is mainly focused on participatory, bottom-up management tools (local management plans and co-management schemes). The resilience of small-scale fisheries’ socio-ecological systems, mainly related to fishers’ capability of adapting their strategies to multiple sets of conditions over time and across areas, is also discussed. We conclude our analysis by investigating actions which could be implemented to allow the unexploited economic, social and cultural potential of small-scale fisheries in Italy to be developed.

Few stock assessments of elasmobranchs have been conducted in the Mediterranean due to the lack of available detailed and precise information. In recent years, in the Mediterranean Sea a major concern on the status of this group does exist and consequently scientists and managers have paid a major attention on the collection of data of fisheries in which they are involved as by-catch, on the impact of different fishing techniques, and on management issues aiming at reducing undesired removals. Information on landings for the more important species is now available in some Mediterranean countries but time series are still too short. Data on age structure of catches is often partial and does not regard all the fisheries in which the species are involved making difficult the reconstruction of the demographic structure of the commercial catches. So far such difficulties made almost impossible the use of age-based analytical models or surplus production models for stock assessment. Recently, stock assessments using simple approaches suitable for data poor stocks were performed for Raja asterias and Raja clavata, Scyliorhinus canicula and Galeus melastomus in the GFCM-GSA9. R. asterias is caught especially by trawlers fleet segments targeting flat fish (15-100 m of depth). R. clavata and S. canicula are in general part of the by-catch of a fishery operating at deeper waters (about 100-200 m) mainly targeting Parapenaeus longirostris, Eledone cirrhosa and Merluccius merluccius. G. melastomus is mainly found in the depth range 200-1200 m and is exclusively caught with bottom trawlers. It constitutes an important by-catch fraction of the Nephrops norvegicus fishery (250-500 m of depth) and the deep-sea shrimps fishery.

The main characteristics concerning the distribution of two of the most important decapod crustaceans of commercial interest in the Mediterranean Sea, the deep-water rose shrimp, Parapenaeus longirostris, and the Norway lobster, Nephrops norvegicus, are studied in the European Mediterranean waters. The study is based on data collected under the MEDITS trawl surveys from 1994 to 2015 from the Gibraltar Straits to the northeastern Levantine Basin (Cyprus waters). The observed differences can be interpreted as different responses to environmental drivers related to the differing life history traits of the two species. In fact, N. norvegicus is a long-living, benthic burrowing species with low growth and mortality rates, while P. longirostris is an epibenthic, short-living species characterized by higher rates of growth and mortality.

Passive nets are currently among the most important fishing gears largely used along the Mediterranean coasts by the small scale fisheries sector. The fishing effort exerted by this sector is strongly correlated with net dimensions. Therefore, the use of passive nets is worldwide managed by defining net length and net drop. The EC Reg. 1967/2006 reports that the length of bottom-set and drifting nets may be also defined considering their weight or volume; however, no practical suggestions for fisheries inspectors are yet available. Consequently, even if such technical measures are reasonable from a theoretical viewpoint, they are hardly suitable as a management tool, due to the difficulties in harbour control. The overall objective of this paper is to provide a quick methodological approach for the gross estimation of passive net length (by net type) on the basis of net volume. The final goal is to support fisheries managers with suitable advice for enforcement and control purposes. The results obtained are important for the management of the fishing effort exerted by small scale fisheries. The methodology developed in this study should be considered as a first attempt to tackle the tangled problem of net length estimation that can be easily applied in other fisheries and areas in order to improve the precision of the models developed herein.

18 pages, 12 figures, 3 tables, Since the first introduction of the landing obligation (a.k.a. Discard ban) in 2015, the EU Mediterranean fisheries are facing some unforeseen challenges. The demersal bottom trawl fisheries, being the most significant contributors to the so-called 'discard problem', are confronted with the greatest challenges. Data from the Italian and the Greek fleet, spanning over two decades (1995-2015), were analysed with the intention of revealing the diversity and heterogeneity of the discard problem, especially for regulated species. Species composition of discards, as well as discarding rates, were shown to be irregular, fluctuating among areas, depth strata, seasons and years. Although fish dominated the discarded gross catch in weight, benthic invertebrates (other than commercial cephalopods and crustaceans) were the taxa discarded almost exclusively. The established minimum conservation reference size was largely ignored by fishers. From a management point of view, the present investigation suggests that the recently established Discard Management Plans lack scientific evidence (given the high intrinsic variability of the parameters and confusion regarding the rules) and provide exemptions from the landing obligation that will in practice allow the average Mediterranean bottom trawl vessel to continue business as usual. Moreover, detecting if these rules are actually respected is an almost impossible task for the Mediterranean control and enforcement authorities. Incentivizing the adoption of fishing technologies and practices that reduce pre-harvest mortality and post-harvest discards, while avoiding damage to sensitive marine species and habitats, seems the only way to move forward, rather than dealing with the problem after it has occurred., This research was funded by the European Commission’s Horizon 2020 Research and Innovation Programme under Grant Agreement No. 634495 for the project Science, Technology and Society Initiative to minimize Unwanted Catches in European Fisheries (MINOUW)

The present study aimed to evaluate the variation over time of the abundance of the populations of five demersal species in the Tyrrhenian Sea (NW Mediterranean) analysing data obtained from trawl surveys and commercial landing monitoring. The influence of some environmental variables (sea surface temperature, wind speed, NAO index) and some fishing effort indices (fishing days, mean size and mean engine power of the trawl vessels) was analysed as well. The species considered for the study were Eledone cirrhosa, Merluccius merluccius, Mullus barbatus, Nephrops norvegicus and Parapenaeus longirostris. From 1991 to 2006, the mean monthly landing rates were computed from the data collected at the auction of Porto Santo Stefano, the most important fishing harbour in the area. A second data set was represented by trawl survey data: two experimental trawl surveys per year have been carried out in the framework of national and international programs on the assessment of demersal resources. The mean biomass (kg/km 2 ) indices were calculated. The time series analyses were carried out by means of Min/Max Auto-correlation Factor Analysis (MAFA) and Dynamic Factor Analysis (DFA). The two techniques provided coherent results, indicating that the two most important trends in the response variables are an increase in terms of both LPUE and survey biomass index, and a fluctuating pattern, even though characterized by a general increasing tendency. What drove these trends is less clear, even though the available evidence suggests that the reduction of fishing effort has been more important than environmental factors.

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

22 pages, 6 figures, 7 tables, supporting information http://dx.doi.org/10.1371/journal.pone.0119330.s001, We investigate long-term changes in the Mediterranean marine resources driving the trawl fisheries by analysing fishers' perceptions (Traditional Ecological Knowledge, TEK) throughout the Mediterranean Sea during the last 80 years. To this end, we conducted an extended set of interviews with experienced fishers that enabled us to classify species (or taxa) as 'decreasing' or 'increasing' both in terms of abundance, as well as average size in the catch. The aspect that most clearly emerged in all the investigated areas over time was the notable increase of fishing capacity indicators, such as engine power and fishing depth range. Atlantic mackerel, poor cod, scorpionfishes, striped seabream, and John Dory demonstrated a decreasing trend in the fishers' perceived abundance, while Mediterranean parrotfish, common pandora, cuttlefish, blue and red shrimp, and mullets gave indications of an increasing temporal trend. Although, as a rule, trawler captains did not report any cataclysmic changes (e.g. extinctions), when they were invited to estimate total catches, a clear decreasing pattern emerged; this being a notable finding taking into account the steep escalation of fishing efficiency during the past century. The overall deteriorating status of stocks in most Mediterranean regions calls for responsible management and design of rebuilding plans. This should include historical information accounting for past exploitation patterns that could help defining a baseline of fish abundance prior to heavy industrial fisheries exploitation. © 2015 Damalas et al., The data acquisition was supported by the European Commission through project EVOMED (“The 20th Century evolution of Mediterranean exploited demersal resources under increasing fishing disturbance and environmental change” (no MARE/2008/11: Lot 4)

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

9 pages, 3 figures, 4 tables, supplementary data http://icesjms.oxfordjournals.org/content/72/9/2600/suppl/DC1, Discarding of commercially important fish species in the bottom trawl fisheries in the northern Mediterranean Seawas investigated by soliciting the long-term recollections of fishers engaged or formerly engaged in such fisheries. The main aim of our investigationwas to describe the prevalence of discarding and its evolution over the past 70 years using information gathered through individual questionnaire-based interviews with fishers from ports in Spain, Italy, and Greece, following a standardized sampling protocol. Although it proved impossible to derive absolute estimates of the volume of discarded catches over the period investigated, we conclude that over the past 70 years, discarding as a practice has gradually increased in the northern Mediterranean trawl fisheries and has been accompanied by a shift in the species composition of the discarded catch. While discarding can occur for a number of reasons, our investigations indicate that discarding in the past was mostly driven by market demand, but recent legal and regulatory constraints have led to changes in fishing strategies and became a significant reason for discards, Data acquisition was supported by the European Commission through the EU project EVOMED (“The 20th Century evolution of Mediterranean exploited demersal resources under increasing fishing disturbance and environmental change”). European Commission, Directorate-General for Maritime Affairs and Fisheries. Open Call for Tenders n8 MARE/2008/11, Proposal for Lot 4, (Contract. N8 SI2 539097)

[The deep water rose shrimp, Parapenaeus longirostris , is a very important commercial species for trawl fleets that fish in the Mediterranean as well as in the Gulf of Cadiz and to the south of Portugal. Despite its importance, its life cycle has not been thoroughly studied and there are discrepancies as to certain aspects, depending on the area. Although spawning takes place throughout the year, two peak periods have been identified between late spring and early autumn. This species is characterized by a differential growth pattern, with females reaching a larger size, and has a life cycle of two to three years. Individuals reach sexual maturity at 8 to 10 months at varying sizes, depending on the area (cephalothorax length 20 to 28 mm in females) and have an average fecundity of 90,000 eggs. The species feeds on a great variety of prey, its main prey being annelid worms (polychaetes) and foraminiferans. The fishery involves a large number of boats, about 2,000 over the whole area here covered. It is basically directed at a single cohort and total catches can reach 10,000 tons a year. La gamba blanca, Parapenaeus longirostris , constituye una especie de elevado interes comercial para las flotas de arrastre que faenan tanto en el Mediterraneo como en el Golfo de Cadiz y sur de Portugal. A pesar de dicha importancia, su ciclo de vida no es del todo bien conocido existiendo discrepancia en determinado aspectos en funcion del area. La puesta tiene lugar a lo largo de todo el ano, si bien presenta dos picos identificados entre final de primavera y principio de otono. Esta especie presenta un crecimiento diferencial, alcanzando mayor tamano las hembras, con un ciclo de vida esta entre dos y tres anos. Alcanzan la madurez sexual entre los 8 y 10 meses variando la talla en funcion del area (entre 20 y 28 mm de Longitud de Cefalotorax en las hembras) y un valor medio de fecundidad de 90000 huevos. Se alimenta de una gran variedad de presas siendo los poliquetos (polychaetes) y foraminiferos los principales. En esta pesqueria estan inmersas un elevado numero de embarcaciones, superando los 2000 barcos en el area tratada. Se desarrolla fundamentalmente sobre en una unica cohorte y con valores que pueden alcanzar las 10000 toneladas anuales. , The deep water rose shrimp, Parapenaeus longirostris , is a very important commercial species for trawl fleets that fish in the Mediterranean as well as in the Gulf of Cadiz and to the south of Portugal. Despite its importance, its life cycle has not been thoroughly studied and there are discrepancies as to certain aspects, depending on the area. Although spawning takes place throughout the year, two peak periods have been identified between late spring and early autumn. This species is characterized by a differential growth pattern, with females reaching a larger size, and has a life cycle of two to three years. Individuals reach sexual maturity at 8 to 10 months at varying sizes, depending on the area (cephalothorax length 20 to 28 mm in females) and have an average fecundity of 90,000 eggs. The species feeds on a great variety of prey, its main prey being annelid worms (polychaetes) and foraminiferans. The fishery involves a large number of boats, about 2,000 over the whole area here covered. It is basically directed at a single cohort and total catches can reach 10,000 tons a year. La gamba blanca, Parapenaeus longirostris , constituye una especie de elevado interes comercial para las flotas de arrastre que faenan tanto en el Mediterraneo como en el Golfo de Cadiz y sur de Portugal. A pesar de dicha importancia, su ciclo de vida no es del todo bien conocido existiendo discrepancia en determinado aspectos en funcion del area. La puesta tiene lugar a lo largo de todo el ano, si bien presenta dos picos identificados entre final de primavera y principio de otono. Esta especie presenta un crecimiento diferencial, alcanzando mayor tamano las hembras, con un ciclo de vida esta entre dos y tres anos. Alcanzan la madurez sexual entre los 8 y 10 meses variando la talla en funcion del area (entre 20 y 28 mm de Longitud de Cefalotorax en las hembras) y un valor medio de fecundidad de 90000 huevos. Se alimenta de una gran variedad de presas siendo los poliquetos (polychaetes) y foraminiferos los principales. En esta pesqueria estan inmersas un elevado numero de embarcaciones, superando los 2000 barcos en el area tratada. Se desarrolla fundamentalmente sobre en una unica cohorte y con valores que pueden alcanzar las 10000 toneladas anuales. ]

The aim of this study was to analyse the main factors affecting catch rates of the most important decapod crustaceans of the bottom trawl fishery in the northern Tyrrhenian Sea, western Mediterranean. Catch per unit effort (CPUE) data (kg/fishing day/boat) of deep water rose shrimp, Parapenaeus longirostris , Norway lobster, Nephrops norvegicus , and red shrimps, Aristaemorpha foliacea and Aristeus antennatus , were collected monthly in the years 1991–1999 at the auction of Porto Santo Stefano, where these species are traditionally exploited by trawlers using traditional trawl nets. The application of cluster analysis to the entire data set allowed the identification of three main “metiers” or fishing tactics, corresponding to different fishing grounds, species assemblages and characteristics of vessels. Two “metiers” corresponded to fishing activity targeting the above-mentioned crustacean species. Generalised linear modelling was used to investigate the influence of factors such as month, year and vessel on catch rates of the species studied. This model explained a considerable amount of variability in the CPUE data, which substantially reflected the differences observed in the trends of monthly landings of these species. Month was an important factor explaining deviance in the CPUE for the deep water rose shrimp, but especially for the two red shrimps. This was mostly due to the temporal pattern in the catchability of these species, as well as the seasonality of the fishing effort targeting these resources. Year significantly contributed to the variation in CPUE of all the species studied, in particular for P. longirostris , confirming that the abundance of this species is subject to distinctive inter-annual fluctuations. Vessel was a significant factor determining variability in CPUE for P. longirostris and, especially, in N. norvegicus . No single boat characteristic such as length, gross registered tonnage and engine power provided a more satisfactory explanation than the vessel factor as a whole. For Norway lobster, the high variation explained by the vessel is attributable to the fact that the fishing fleet targeting this species was the most heterogeneous, involving two different “metiers” and, therefore, boats differing in size and in fishing practices.

The selectivity of a traditional trammel net, a monofilament trammel net and a gill net for Lithognathus mormyrus (striped sea-bream), Diplodus annularis (annular sea-bream) and Mullus barbatus (red mullet) was investigated in two coastal areas (central Adriatic sea and southern Ligurian sea). Three mesh sizes were tested for each set net: 45, 70 and 90 mm (stretched-mesh size). Selectivity was assessed by the indirect Sechin model based on the measurement of maximum body girth and head girth. The 45-mm mesh size was the most efficient for all the target species irrespective of net type. The catches obtained with the 90-mm meshes were always very low as were the catches of D. annularis and M. barbatus with the 70-mm mesh. Although most fishes of the three target species were caught by gilling and/or wedging, with all gears a number of individuals were also caught by virtue of the tangled and/or pocket effects. Their proportion, lowest and generally negligible in the gill net, higher in the monofilament and highest in the standard trammel net, caused a progressive widening of size-catch ranges, confirming the low selectivity of trammel nets. The 45-mm mesh appears to be the most suitable for the exploitation of the target species because it caught the highest number of specimens while it largely spared the juveniles.

10 pages, 4 figures, 4 tables, We conducted interviews of a representative sample of 106 retired fishers in Italy, Spain and Greece, asking specific questions about the trends they perceived in dolphin and shark abundances between 1940 and 1999 (in three 20 year periods) compared to the present abundance. The large marine fauna studied were not target species of the commercial fleet segment interviewed (trawl fishery). The fishers were asked to rank the perceived abundance in each period into qualitative ordinal classes based on two indicators: frequency of sightings and frequency of catches (incidental or intentional) of each taxonomic group. The statistical analysis of the survey results showed that both incidental catches and the sighting frequency of dolphins have decreased significantly over the 60+ years of the study period (except for in Greece due to the recent population increase). This shows that fishers' perceptions are in agreement with the declining population trends detected by scientists. Shark catches were also perceived to have diminished since the early 1940s for all species. Other long-lived Mediterranean marine fauna (monk seals, whales) were at very low levels in the second half of the 20th century and no quantitative data could be obtained. Our study supports the results obtained in the Mediterranean and other seas that show the rapid disappearance (over a few decades) of marine fauna. We show that appropriately designed questionnaires help provide a picture of animal abundance in the past through the valuable perceptions of fishers. This information can be used to complement scientific sources or in some cases be taken as the only information source for establishing population trends in the abundance of sensitive species, The data acquisition was supported by the European Commission through project EVOMED (“The 20th Century evolution of Mediterranean exploited demersal resources under increasing fishing disturbance and environmental change”, n° MARE/2008/11: Lot 4). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

The impact of the gillnet fishery on Merluccius merluccius (European hake) was investigated in the northern Tyrrhenian Sea, western Mediterranean. Four mesh sizes were tested: 53, 62.5, 70 and 82 mm. Horse mackerel (Trachurus trachurus), hake and tub gurnard (Chelidonichthys lucerna) dominated the catches, from a minimum of 89% (82 mm mesh) to a maximum of 97.8% (70 mm) of the biomass caught. Efficiency of the four meshes was not significantly different with respect to the total hake catches. Selectivity on M. merluccius was assessed by Sechin and SELECT methods. Tangling was an important catch modality for hake, as evidenced by the results of the Sechin model which described only the first mode of the size distributions corresponding to the entangled specimens. SELECT showed that the bi-modal function gave the best adjustment to the length-frequency distributions; the modal catch sizes were 33, 39.2, 43.6 and 51 cm total length respectively for the 53, 62.5, 70 and 82 mm mesh sizes. Taking into account the size of first maturity for females (35.1 cm TL), 62.5 mm is the most adequate mesh for exploiting hake as it gives some protection to both immature specimens and large females. Se estudió el impacto de la pesquería con redes de enmalle sobre la merluza, Merluccius merluccius, (merluza europea) en el norte del mar Tirreno, Mediterráneo noroccidental. Se utilizaron cuatro tamaños de malla: 53, 62.5, 70 y 82 mm. Los peces Trachurus trachurus, M. merluccius y Chelidonichthys lucerna dominaron la biomasa capturada, con un mínimo del 89% (malla de 82 mm) y un máximo del 97.8% (malla de 70 mm). La eficiencia de las cuatro mallas no resultó estadísticamente diferente. La selectividad sobre M. merluccius fue estudiada con los métodos Sechin y SELECT. El enredamiento resultó una importante manera de captura, como evidenció el método Sechin, con un buen ajuste sólo para la primera moda de las distribuciones de talla, correspondiente a ejemplares capturados por enmalle. Con el modelo SELECT la función bimodal fue la mejor para describir las estructuras de talla; las tallas modales de captura fueron 33, 39.2, 43.6 y 51 cm de longitud total, para las mallas de 53, 62.5, 70 y 82 mm respectivamente. Teniendo en cuenta la talla de primera madurez, la malla de 62.5 mm es probablemente la más adecuada para la explotación de la merluza, permitiendo una cierta protección tanto de los inmaduros como de las hembras grandes.

14 pages, 9 figures, 4 tables, Temporal and spatial variation in Merluccius merluccius recruitment in the Northwest Mediterranean is examined, and recruitment indices are derived from monthly M. merluccius catch rates of four bottom-trawl fleets operating in Spanish and Italian waters during the period 1991-1999. Where M. merluccius catches were not recorded by size category, multivariate techniques were applied to species proportions in order to identify catch records most representative of recruit abundance. Selected catch rates were analysed by generalized linear models (GLMs) to estimate recruitment indices. The GLMs explain large proportions of the variation in recruit abundance (50-84%) and indicate significant annual and seasonal variation in recruitment strength. Vessel was by far the most important factor affecting catch rates of recruits, stressing the need to account for vessel characteristics when analysing commercial catch data for stock assessment. Seasonal patterns of recruitment reveal similarities among the study areas and interannual variations within areas. One major recruitment peak was identified in each area during either spring/summer or late summer/winter. In most areas, recruitment between 1991 and 1999 seemed to decline, but this could not be confirmed owing to high interannual variability. The coherence of annual fluctuations in recruitment indices with those of MEDITS surveys supports the present results, The study was supported by funding provided by the European Commission, DG Fisheries, under project contract 98/053 ‘‘Factors affecting catch rates of NW Mediterranean trawl fleets and derivation of standardized abundance indices’’

Information on distribution, relative abundance and size composition of the pleuronectiform species Citharus linguatula, Lepidorhombus boscii and Solea vulgaris was obtained during the MEDITS trawl surveys, carried out in a wide area of the Mediterranean Sea from 1994 to 1999. The three species showed a wide geographic distribution, as they were collected in all the macro-areas investigated, but with some differences in degree of presence among the 40 geographic sectors. Variations in abundance indices, analysed on a spatio-temporal basis with a Generalised Linear Model, were mostly related to the depth stratum and the macro-area. C. linguatula and S. vulgaris were especially found from 10 to 100 m depth, while L. boscii was most abundant on bottoms ranging from 100 to 500 m depth. The three species showed the highest abundance indices (kg/km2) in the Gulf of Lions, in the Greek Seas and along the Sardinian coasts. Especially for L. boscii and C. linguatula, the demographic structure showed that the sampled populations were mainly constituted by juveniles. The lowest biomass and abundance indices were obtained for S. vulgaris, whose catch was mainly composed of adult fish.

This study aimed to test the effectiveness of a “guarding net”, a device placed at the bottom of a trammel net, for reducing unwanted catches in the caramote prawn trammel net fishery of the Ligurian Sea. This specialized and profitable fishery is affected by unwanted catches that generate high discard rates and damage to the nets, with environmental impacts and costs for fishermen. The experimental study consisted in comparing the catches of a standard trammel net (STN) with those of two “experimental” trammel nets, e.g. STNs provided with a guarding net of 19 cm (TGN20) and 24 cm height (TGN25), respectively. The guarding net, a strip of gillnet placed at the bottom of the net, can be considered a by-catch reducer device (BRD). Some fishermen of the investigated fishery have been using this device for several years. The results of the 15 experimental fishing trials performed from June to July 2016 indicate that the guarding nets significantly reduce discards (e.g. crabs and other invertebrates); the biomass of the unwanted species caught was 75% lower than that produced by the STN. The catch rates of the target species obtained with TGN20 and TGN25 were also significantly lower than those of the STN, though of a lesser amount. Nonetheless, this economic loss can be compensated by the decrease in sorting time and material and labour costs that can be achieved using the guarding net., El objetivo de este trabajo fue testar los efectos de un “faldón”, una red colocada en la parte inferior de un trasmallo, para reducir los descartes en la pesquería del camarón del mar Ligur. Se trata de una pesquería especializada y rentable, afectada por capturas no deseadas, que generan descartes y daños a las redes, con impacto ambiental y costes para los pescadores. Se llevaron a cabo pescas experimentales, para comparar la captura de un trasmallo estándar (STN) con la de dos trasmallos “experimentales”, construidos a partir de un trasmallo estándar, con el ajuste de un faldón de 19 cm de altura (TGN20), y de un faldón de 24 cm (TGN25). Este faldón, una banda de red de enmalle, se puede considerar como un dispositivo reductor de capturas accesorias (BRD). Algunos pescadores de la pesquería investigada ya utilizan este dispositivo desde hace algunos años. Los resultados de las quince pruebas experimentales, realizadas de junio a julio 2016, muestran que el faldón de red de enmalle contribuye significativamente a reducir los descartes (cangrejos y otros invertebrados), con una reducción de la biomasa de las especies descartadas hasta el 75%, respecto al trasmallo estándar. Al mismo tiempo, también las tasas de captura de las especies objetivo obtenidas con TGN20 y TGN25 fueron significativamente más bajas que las del STN, aunque de menor magnitud. Sin embargo, esta pérdida económica puede ser compensada por la disminución del tiempo de trabajo, de los costes del material y de la mano de obra, que se pueden lograr utilizando un trasmallo con “faldón”.