Harbour seal monitoring and evaluation for the Luchterduinen offshore windfarm : Final report

• Main Authors: Brasseur, Sophie, Schop, Jessica, Cremer, Jenny, Aarts, Geert
• Format: Report
• Language: English
• Published: Wageningen Marine Research 2018
• Subjects: Life Science; harbour seal
• Online Access: https://research.wur.nl/en/publications/harbour-seal-monitoring-and-evaluation-for-the-luchterduinen-offs; https://doi.org/10.18174/461959

Though it seems unlikely that marine mammals, including seals suffer at a large scale from direct mortality caused by the construction or operation of windfarms at sea, they are likely to be affected by disturbance and habitat alterations.In 2014, Luchterduinen windfarm was constructed in the Dutch coastal zone south west of IJmuiden and the permit (WV/2009-1229) requested monitoring with respect to both harbour and grey seals. Two main questions were formulated:1. How do seals use the coastal zone? The aim was to gain insight in harbour and grey seal movement routes along the Dutch North Sea coastal zone (between the Wadden Sea and the Delta region).2. What is the impact of Luchterduinen on seals? (with a focus on the impact of piling).This rapport discusses the results of the harbour seal studies. The initial monitoring (T0-T1; 2013-2015) based on a series of studies on the movements and habitat use of harbour seals deployed in spring (March), was timed in relation to the construction (2014) and operation of the windfarm. These studies were evaluated after T1 (in 2016). It was concluded that by limiting the study to spring deployments, the harbour seals’ habitat use during a large part of the year was missing. Since harbour seals moult in summer, the trackers attached to the fur typically fell off in June –July. In this study (T2-T3) therefore, a deliberate choice was made to study the behaviour of the seals in the post moult, from September onwards. A total of 18 seals were tracked from September onwards: in 2016 (T2) 6 from the Wadden Sea area and 6 from the Delta and again 6 from the Wadden Sea area in 2017(T3).With longer track durations of 20 to 187 days (mean 106 ± 46 days) in this last study information has been collected covering seven calendar months, six of which had not been studied before in this region. However there was large variation in behaviour, possibly but not solely as a result of the male bias in the sample (11 males, 7 females). Though the maximum and mean distance travelled by the seals ...