Short summary

Animal movement shapes how individuals interact with their environment, influencing population stability and broader ecological patterns. This thesis used biotelemetry to understand how migratory fish use the Dutch Wadden Sea, a shallow coastal ecosystem facing population declines. While the area likely serves multiple roles for migratory fish, effective conservation is hindered by a critical lack of fundamental data on the spatial and temporal characteristics of fish presence and connectivity to adjacent habitats. Multi-year tracking data collected by this study showed strong seasonal patterns for European sea bass, thicklip grey mullet, and thinlip grey mullet, with fish arriving in spring and leaving in autumn, and many individuals returning to the same areas each year.

Despite overlap, the two mullet species differed in timing, habitat preference, and space use. We also found evidence that the region may serve as a nursery for the Critically Endangered tope shark, based on the unexpected capture of newborns. These findings highlight the Wadden Sea’s importance for migratory fish and support the need for conservation approaches that reflect the true scales of fish migration and encompass their complete life histories.

Practical information:

  • Title: Life in the shallows: Tracking fish movement within and beyond the Wadden Sea
  • Supervisors: Dr Tom Buijse (WUR), Dr Allert Bijleveld (NIOZ) & Dr Erwin Winter (WMR)
  • Date: 10 July 2025, 13.00
  • Location: Omnia Auditorium, Wageningen University & Research

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