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Viability of the Northeast Atlantic harbour porpoise and seal population (genetic and ecological study): final report
Das, K.; Drouguet, O.; Fontaine, M.C.; Holsbeek, L.; Jauniaux, T.; Michaux, J.; Joiris, C. (2007). Viability of the Northeast Atlantic harbour porpoise and seal population (genetic and ecological study): final report. Belgian Science Policy: Brussel. 42 pp.

Available in Authors 
    VLIZ: Open Repository 119989 [ OMA ]
Document type: Final report

Keywords
    By catch; Fisheries; Isotopes; Marine mammals; Phoca vitulina Linnaeus, 1758 [WoRMS]; Phocoena phocoena (Linnaeus, 1758) [WoRMS]; ANE, North Sea [Marine Regions]; Marine

Project Top | Authors 
  • Viability of the Northeast Atlantic harbour porpoise and seal populations (genetic and ecological studies), more

Authors  Top 
  • Das, K., more
  • Drouguet, O.
  • Fontaine, M.C., more
  • Holsbeek, L., more

Abstract
    Harbour porpoises (Phocoena phocoena) and harbour seals (Phoca vitulina) are far more abundant along our coast compared to the beginning of the nineties. Human impact on these species is however hard to establish, mainly due to lack of information on marine mammal population ecology, density, distribution and diversity. This project aims to gain further knowledge on the viability of the harbour porpoise and harbour seal populations in the North Sea (focusing mainly on its southern Bight) through

    - The characterisation of their genetic structure and diversity (through mtDNA and microsatellites in harbour porpoises)
    - A better understanding of their feeding ecology (through d13C and d15N measurements in muscles)
    - The assessment of their susceptibility of being trapped accidentally in fishing nets (post-mortem investigations)

    Harbour porpoise and harbour seal occupied the top trophic levels but displayed different feeding habits as inferred from their d13C and d15N mean values. Harbour porpoises displayed lower mean d15N values suggesting a lower trophic position likely oriented towards small planktivorous fish such as herring and lesser sandeel. However, both their recent high abundance and their dietary preferences might lead to a higher susceptibility to by-catch as revealed by the significant emergence of net entrapment and net marks revealed by post-mortem investigations. The question rises about the sustainability of these incidental captures. Furthermore, genetic investigations revealed a higher fragmentation of the porpoises collected along the coast of France, Belgium and Netherlands. This apparent fragmentation is of particular importance from a conservation point of view and enhances the fact to protect in priority these last populations. Our study showed importance of multidisciplinary approaches (post-mortem investigations, stable isotope measurements (d13C and d15N measurements) and genetic investigations using mtDNA and microsatellites) to apprehend the question of marine mammal survival in our waters.

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