Aarts, Geert

Catchpole, Tom

Feekings, Jordan P.

Kempf, Alexander

Madsen, Niels

Poos, Jan Jaap

Pout, Alastair

Rochet, Marie‐Joelle

Ulleweit, Jens

Ulrich, Clara

van Helmond, Aloysius

Vandemaele, Sofie

Online Research Database In Technology

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Downloaded from orbit.dtu.dk on: Dec 20, 2017Spatiotemporal variability of North Sea cod discardsFeekings, Jordan P.; Poos, Jan Jaap; Aarts, Geert; Madsen, Niels; van Helmond, Aloysius; Catchpole,Tom;  Rochet, MarieJoelle; Pout, Alastair; Ulleweit, Jens; Vandemaele, Sofie; Ulrich, Clara; Kempf,AlexanderPublication date:2012Document VersionPublisher's PDF, also known as Version of recordLink back to DTU OrbitCitation (APA):Feekings, J. P., Poos, J. J., Aarts, G., Madsen, N., van Helmond, A., Catchpole, T., ... Kempf, A. (2012).Spatiotemporal variability of North Sea cod discards.Spatiotemporal variability of North Sea cod discards Discarding is currently one of the most important issues within commercial fishing, and has prompted a commitment from the European Council to end discarding through a phased ban. However, the consequences are still poorly understood due to incomplete knowledge on the spatiotemporal pattern of discards, which tend to be highly variable in space and time. Here we show discard rates of small and large cod (Gadus morhua L.) in the North Sea to be highly variable in their spatial and temporal (inter-annual and seasonal) distributions.   Methods: To elucidate the discarding patterns of cod in the North Sea we employ generalized additive mixed models (GAMMs) using discard data from 11370 fishing events collected throughout the period 2003 – 2010. Data were collected across seven European Union (EU) Member States as part of the EU Data Collection Framework (DCF). Furthermore, we aim to account for the variability in discards that occurs as a result of depth, gear and its associated mesh size, and vessel specific characteristics. Discards less than and greater than MLS (small and large cod respectively) were analysed separately. The discard data defined above is collected by different segments of the fishing fleets. Hence, such ….  Jordan Feekings1*, Jan Jaap Poos2, Geert Aarts2,3, Niels Madsen1, Aloysius van Helmond2, Tom Catchpole4, Marie-Joelle Rochet5, Alastair Pout6, Jens Ulleweit7, Sofie Vandemaele8,9, Clara Ulrich10, Alexander Kempf7    This study aims to elucidate the discarding patterns of cod throughout the entire North Sea while accounting for the variability that occurs as a result of additional drivers. Demonstrating detailed spatiotemporal discarding patterns provides opportunities to further develop spatial management. This facilitates the move to discard free fisheries as part of the proposed reforms of the CFP and can illustrate what the impacts will be on European fishing fleets. ICES Annual Science Conference 2012, Bergen, Norway                               ICES CM 2012/ C:31   Acknowledgements: This study was conducted under the MariFISH project: BADMINTON - Bycatch And Discards: Management, Indicators, Trends And Location   Fig.1. Model predicted densities of small (upper panel) and large (lower panel) cod discards in North Sea 2003 – 2010.     1 Technical University of Denmark, National Institute of Aquatic Resources, North Sea Science park, PO Box 101, DK-9850 Hirtshals, Denmark 2 IMARES Wageningen UR, Institute for Marine Resources and Ecosystem Studies, PO Box 68,1970 AB IJmuiden, the Netherlands 3 Wageningen UR, Department of Aquatic Ecology and Water quality Management, PO Box 47, 6700 AA Wageningen, The Netherlands 4 Centre for Environment, Fisheries and Aquaculture Science, Lowestoft, UK 5 IFREMER, B.P. 21105, 44311 Nantes CEDEX 03, France 6 Marine Scotland Science, Marine Laboratory, PO Box 101, 375 Victoria Road, Aberdeen AB11 9DB, UK 7 Johann Heinrich von Thünen Institute [vTI], Federal Research Institute for Rural Areas, Forestry and Fisheries, Institute of Sea Fisheries, Palmaille 9, D-22767 Hamburg, Germany 8 The Institute for Agricultural and Fisheries Research (ILVO), Ankerstraat 1, B-8400 Ostend, Belgium 9 University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp, Belgium 10 Technical University of Denmark, National Institute of Aquatic Resources, Charlottenlund Slot – Jægersborg Allé 1, DK-2920  Charlottenlund, Denmark *Corresponding author: jpfe@aqua.dtu.dk  data alone cannot define whether heterogeneity in discard rates results from fishing fleet characteristics (e.g. gear type and mesh size) or whether it is the result of spatiotemporal patterns in cod distribution. Therefore, data from the biannual international bottom trawl survey (IBTS) are used to complement the discard data.    Results: Analyses revealed highly significant spatiotemporal heterogeneity among small (<MLS) and large (≥MLS) cod throughout the North Sea on both inter-annual and season time scales (Fig 1). Our analyses also revealed depth, time, location, gear type and mesh size, as well as individual vessel characteristics, to be correlated with discard rates of cod (Fig. 2).   Conclusions: Here we have described the spatiotemporal distribution of small and large cod discards throughout the entire North Sea and conclude that clear seasonal and inter-annual changes have taken place. Knowledge of the spatiotemporal distribution of discards provides valuable information for management. The mortality of cod imposed by discarding could be reduced by defining areas where the use of more selective fishing methods are mandatory and ensuring that vessels catching cod have sufficient quota to land it.  A ban on discards will likely face economic, regulatory, and political hurdles. Under a discard ban several issues emerge including: i) How to minimise the capture of juveniles and large cod for which there is no quota under a discard ban; ii) How to ensure discarding does not take place.  The success of a discard ban will depend critically on complementary management measures addressing these issues.   Fig. 2. Model predicted effects of significant smoothing functions (solid lines) on the discard rates of small (top row) and large cod (bottom row) in the North Sea, 2003 – 2010. Dotted lines represent the 95% confidence limits. Vertical bars along the x-axis indicate observational values.  

Spatiotemporal variability of North Sea cod discards

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Spatiotemporal variability of North Sea cod discards

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