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  • 1
    Publication Date: 2017-05-02
    Description: Resolving drivers of spatial synchrony in marine species is fundamental for the management and conservation of deep-sea ecosystems. Here we examine an 11-year data set of monthly catches per unit of effort (CPUE) of the red-shrimp Aristeus antennatus. These data comprise 16 locations of two population subunits in the Western Mediterranean, the Catalan coast and the Balearic archipelago. The analysis of their seasonal covariation and its space-time structure showed small-scale geographical segregation of locations linked with the seasonal fluctuations of CPUE. Results further revealed that seasonal synchrony dominates at short spatial scales (ca. 50 km), while asynchrony prevails are broader spatial scales (ca. 200-300 km). This spatial pattern, however, varied over the period examined, although it was specific for each population subunit suggesting contrasting drivers of seasonal synchrony. The Balearic Islands, a patchier population subunit, displayed a seasonal synchrony pattern mainly dependent on biological and oceanographic processes at local scales. By contrast, in the Catalan coast, the pattern appeared related with regional-scale climate, which triggers spatial differences in the phenology of primary producers and the timing of food advection to the seabed. These cascading processes depicted by our investigation shed light on underlying mechanisms shaping the temporal synchrony of broadly distributed deep-sea populations.
    Type: Article , PeerReviewed
    Format: text
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  • 2
    Publication Date: 2012-03-01
    Description: The stock concept plays a pivotal role in fisheries assessment and management. Stocks are defined according to biological, geographical, economic or socio-political factors. The General Fisheries Commission for the Mediterranean (GFCM) has established thirty management geographical sub-areas (GSAs) based on political and statistical considerations rather than biological or economic factors. Here, we present our view on the main biological and ecological aspects that should be considered for delineating different management units in the Mediterranean. We focus on the Balearic Islands (GSA05) as a case study highlighting its specificities compared to the adjacent coast of the Iberian Peninsula (GSA06), but the approach could be generalized to the problem of identifying stock boundaries in other areas. The work is based on published information from different marine disciplines such as geomorphology, ecology and fisheries, combined with the analysis of new data coming from official fishery statistics and scientific surveys. This approach avoids the important drawbacks (inconclusive results, high costs) of other time-consuming techniques used in stock identification, such as genetics. According to the information presented, we conclude that GSA05 should be maintained as an individualized area for assessment and management purposes in the western Mediterranean.
    Print ISSN: 0214-8358
    Electronic ISSN: 1886-8134
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 3
    Publication Date: 2012-03-01
    Description: We assessed the elasmobranch communities exploited by the bottom trawl fishery off the Balearic Islands (northwestern Mediterranean) by analysing two time series containing information with different levels of detail: 1) a long-term series containing the abundance indices of the whole elasmobranch community landed from 1965 to 2009; and 2) a shorter time series from 2000 to 2009 from two different data sources (daily sales records: 2000-2009; bottom trawl surveys: 2001-2009), with information that allowed the shelf and slope to be analysed separately and different community parameters and abundance indices to be studied. Temporal trends of all these variables were used as ecological status indicators and tested with generalized additive models and analysis of variance. They were finally summarised using the Traffic Light methodology. The long-term series showed two marked trends, an inter-annual decreasing trend that would be a consequence of the large increase in fishing effort, and an intra-annual trend with a clear peak in May in accordance with the seasonal biological cycle of these species. However, data from the last ten years revealed differences between the shelf and slope, as some parameters increased significantly over time on the shelf but did not follow any trend on the slope. The Traffic Light methodology captured these differences well, demonstrating its usefulness for interpreting ecological transitions at a glance.
    Print ISSN: 0214-8358
    Electronic ISSN: 1886-8134
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 4
    Publication Date: 2021-12-29
    Description: Commission Decision of 25 February 2016 setting up a Scientific, Technical and Economic Committee for Fisheries, C(2016) 1084, OJ C 74, 26.2.2016, p. 4–10. The Commission may consult the group on any matter relating to marine and fisheries biology, fishing gear technology, fisheries economics, fisheries governance, ecosystem effects of fisheries, aquaculture or similar disciplines. This report, on methods for supporting stock assessment in the Mediterranean (STECF-21-02), addresses the data checking and preparation for stock assessment once the data has been submitted following the annual data calls. The report provides an overview of the data errors and quality control carried out on both commercial landings data and MEDITS survey data. The analyses reported also address the small fraction of commercial catch with sampling gaps, and how these are assigned appropriate length frequency distributions. The results of these check and assignments are provided by species, GSA and country. Quality checks were carried out on Medits data check consistency of the main reporting files and highlighting where data inconsistencies occurred. Additionally the total landings reported to the European Commission under the Black & Med-Sea data call, the Fisheries Independent Data call and the Annual Economic Report data call were compared at species aggregated to GSA. Some important differences were observed and these are reported. In addition the EWG reviewed a technical report on the sampling of commercial catch in the Greek Fisheries, the review and some suggested further work are included in this report.
    Description: European Union, Joint Research Centre
    Description: Published
    Description: Refereed
    Keywords: Stock assessment ; Fisheries management
    Repository Name: AquaDocs
    Type: Report
    Format: 1269pp.
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  • 5
    Publication Date: 2023-12-20
    Description: Commission Decision of 25 February 2016 setting up a Scientific, Technical and Economic Committee for Fisheries, C(2016) 1084, OJ C 74, 26.2.2016, p. 4–10. The Commission may consult the group on any matter relating to marine and fisheries biology, fishing gear technology, fisheries economics, fisheries governance, ecosystem effects of fisheries, aquaculture or similar disciplines This report documents the outcomes of STECF Expert Working Group 23-09: 2023 stock assessments of demersal stocks in the Western Mediterranean Sea from the meeting held in hybrid mode from 4th to 10th September 2023. A total of 20 fish stocks considered. Nine stocks were evaluated by means of a statistical catch at age (SCAA) model (a4a). Due to the lack of survey information in 2022, five stocks were evaluated through a catch weight projection and short-term forecast. The methodological approach is described in the last part of this Executive Summary, and in the Report. In 2022, index- based advice was given for three stocks (ARA8-9-10-11 and NEP11 on two years basis while for MUT 10 just for one year), and they were re-evaluated by EWG 23-09. The advice for ARA8-9-10-11 and NEP11 have been confirmed while for MUT 10 the missing index information led the group to consider downgrading the advice from an index-based one to a catch only advice approach (ICES Category 5). Two stocks for which the index-based advice provided in 2021 (2 years advice) have been evaluated again looking for a plausible fully analytical assessment. None of the model setting tried was able to provide acceptable results, therefore a biomass index-based advice is given again. The content of the report gives the STECF terms of reference; the basis of the evaluations; assessments, reference point calculations; summaries of state of stock and advised catch or F based on either the MSY approach for assessed stocks and category 3 and 5 based advice for those without assessments. The report contains the full stock assessment reports, the exploration of assessments and category 3 and 5 evaluations for the remaining stocks. The report also contains the STECF observations and conclusions on the assessment report. These conclusions come from the STECF mini plenary meeting October 2023.
    Description: European Commission
    Description: Published
    Description: Refereed
    Keywords: Fishery management ; Common Fishery Policy ; MSY ; European Commision ; Fish stock assessment
    Repository Name: AquaDocs
    Type: Report
    Format: 813pp
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  • 6
    Publication Date: 2024-04-22
    Description: Amongst other factors, topographic features can influence the genetic variability among populations of marine organisms. This applies to host species but also to their parasites, which are poorly studied regarding this aspect, as well as with regard to their use as bioindicators. In the present work, the ribosomal DNA (28S rDNA) was used to assess genetic diversity of Grillotia (Cestoda, Trypanorhyncha) larvae in one of its paratenic hosts, namely Etmopterus spinax, across five different regions (off Scotland, Celtic, Alboran and Balearic Seas and off Cyprus) belonging to three major geographic areas (Northeast Atlantic, western and eastern Mediterranean). The obtained sequences revealed a total of 18 polymorphic sites and 17 haplotypes, as well as significant values of variance throughout the five different regions. Reconstructed phylogenetic trees highlighted that all Grillotia sp. sequences formed a monophyletic group, but divergent lineages split into different main clades which were in relation to the area of origin, with a consistent cluster of sequences from the Atlantic Ocean, as well as another from the Eastern Mediterranean. In contrast, low genetic differentiation was observed between samples from Balearic and Alboran Seas, and with respect to Grillotia sp. larvae from the Gulf of Naples analysed in a previous study. Geographical differences in parasite infection descriptors (prevalence, abundance, and intensity) were assessed, revealing significant differences among the sampled regions. The present study indicates that geographical distance and submarine barriers affect not only the connectivity of hosts but also their parasite infrapopulations by limiting interpopulation dispersal. It underlines the usefulness of parasites as biological tags for the study of susceptible and data-poor host species such as deep-water sharks and its potential implications for host population management and protection measures.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
    Format: application/pdf
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