Characterizing and predicting the distribution of Baltic Sea flounder (Platichthys flesus) during the spawning season

Research output: Research - peer-reviewJournal article – Annual report year: 2017

  • Author: Orio, Alessandro

    Swedish University of Agricultural Sciences, Sweden

  • Author: Bergström, Ulf

    Swedish University of Agricultural Sciences, Sweden

  • Author: Casini, Michele

    Swedish University of Agricultural Sciences, Sweden

  • Author: Erlandsson, Mårten

    Swedish University of Agricultural Sciences, Sweden

  • Author: Eschbaum, Redik

    University of Tartu, Estonia

  • Author: Hüssy, Karin

    Section for Oceans and Arctic, National Institute of Aquatic Resources, Technical University of Denmark, Kemitorvet, 2800, Kgs. Lyngby, Denmark

  • Author: Lehmann, Andreas

    GEOMAR - Helmholtz Centre for Ocean Research Kiel, Germany

  • Author: Ložys, Linas

    Nature Research Centre, Lithuania

  • Author: Ustups, Didzis

    Institute of Food Safety Animal Health and Environment BIOR, Latvia

  • Author: Florin, Ann-Britt

    Swedish University of Agricultural Sciences, Sweden

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Identification of essential fish habitats (EFH), such as spawning habitats, is important for nature conservation, sustainable fisheries management and marine spatial planning. Two sympatric flounder (Platichthys flesus) ecotypes are present in the Baltic Sea, pelagic and demersal spawning flounder, both displaying ecological and physiological adaptations to the low-salinity environment of this young inland sea. In this study we have addressed three main research questions: 1) What environmental conditions characterize the spatial distribution and abundance of adult flounder during the spawning season? 2) What are the main factors defining the habitats of the two flounder ecotypes during the spawning season? 3) Where are the potential spawning areas of flounder? We modelled catch per unit of effort (CPUE) of flounder from gillnet surveys conducted over the southern and central Baltic Sea in the spring of 2014 and 2015 using generalized additive models. A general model included all the stations fished during the survey while two other models, one for the demersal and one for the pelagic spawning flounder, included only the stations where each flounder ecotype should dominate. The general model captured distinct ecotype-specific signals as it identified dual salinity and water depth responses. The model for the demersal spawning flounder revealed a negative relation with the abundance of round goby (Neogobius melanostomus) and a positive relation with Secchi depth and cod abundance. Vegetation and substrate did not play an important role in the choice of habitat for the demersal ecotype. The model for the pelagic spawning flounder showed a negative relation with temperature and bottom current and a positive relation with salinity. Spatial predictions of potential spawning areas of flounder showed a decrease in habitat availability for the pelagic spawning flounder over the last 20 years in the central part of the Baltic Sea, which may explain part of the observed changes in populations' biomass. We conclude that spatiotemporal modelling of habitat availability can improve our understanding of fish stock dynamics and may provide necessary biological knowledge for the development of marine spatial plans.
Original languageEnglish
JournalJournal of Sea Research
Volume126
Pages (from-to)46-55
ISSN1385-1101
DOIs
StatePublished - 2017
CitationsWeb of Science® Times Cited: 2

    Research areas

  • Biological ecotypes, Baltic Sea, Habitat modelling, Essential fish habitat, Spawning grounds
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