Down load report – Catalan.

Monitoring of anchoring sites in Ibiza and Formentera – summer 2017

Since 2014, GEN-GOB has carried out studies to categorize the different anchoring sites in Ibiza and Formentera. In 2014 and 2016, the anchoring sites of cala d’Hort, Porroig, and Talamanca were identified. In these studies, we categorized the fixed anchoring systems, the number of yachts anchored, and the state of health of Posidonia oceanica meadows was described through underwater surveys.

In this study, summer 2017, GEN-GOB has categorized the different anchoring sites of Ibiza and Formentera, with special focus to Ses Salines Natural Parc.

In this study, we have used three different types of methodologies

  • Ais monitoring of the yachts anchored in Posidonia oceanica meadows in Ibiza and Formentera.
  • Geolocation “in situ” of the yachts anchored in Posidonia oceanica meadows in Ses Salines Natural Parc.
  • Descriptive characterization of Posidonia oceanica meadows.

Main conclusions of the report

  • The results from the AIS monitoring, and the fieldwork of geolocation of yachts, indicates that in Ses Salines Natural Park, anchoring in Posidonia oceanica meadows was happening in summer 2017. This anchoring is produced by small, medium and large yachts. The sites most affected by these massive anchoring were: ses Illetas, in Formentera, and Salines in Ibiza. In these sites, we have measured with AIS densities in the study period of 21 yachts per 0.25 km2 in ses Illetes, and 12 yachts per 0.25 km2 in Sallies.
  • Outside the Natural Park, the areas with highest concentration of yachts were es Xarcu- es Jondal, Figueretes, Talamanca, and es Torrent – Porroig.
  • In the study cases analyzed, we can infer that a mega –yacht can erode between 1.000 and 5.000 m2 of Posidonia oceanica.
  • This information, obtained through AIS analyses, it was corroborated with diving surveys in 5 sites of the Natural Park. In these areas, we have documented degradation signs of Posidonia oceanica
  • This recent degradation is combined with degradation from previous years that accelerates the loss of Posidonia oceanica meadows due to yacht anchoring.