Summer Abundance of Harbour Porpoises (Phocoena phocoena) in the Coastal Waters of Iceland and the Faroe Islands

  • Anita Gilles University of Veterinary Medicine Hannover, Foundation, Institute for Terrestrial and Aquatic Wildlife Research, 25761 Büsum, Germany https://orcid.org/0000-0001-7234-8645
  • Thorvaldur Gunnlaugsson Marine and Freshwater Research Institute, P.O. Box 1390, IS-121 Reykjavík, Iceland
  • Bjarni Mikkelsen Museum of Natural History, FO-100 Tórshavn, Faroe Islands
  • Daniel G. Pike Esox Associates, 1210 Ski Club Road, North Bay, Ontario, Canada, P1B 8E5
  • Gísli Víkingsson Marine and Freshwater Research Institute, P.O. Box 1390, IS-121 Reykjavík, Iceland https://orcid.org/0000-0002-4501-193X
Keywords: harbour porpoise, abundance estimate, Iceland, Faroe Islands, aerial survey, distance sampling, cetacean

Abstract

This study presents the first fully corrected abundance estimates for the harbour porpoise (Phocoena phocoena) for Iceland and the Faroe Islands. In both regions reliable estimates are needed to assess the impact of by-catch and other threats to harbour porpoises. Aerial surveys with harbour porpoise as a secondary and main target species were conducted in the summers of 2007 and 2010 in Icelandic and in Faroese coastal waters respectively. In Iceland, the cue counting procedure was used (which also produces the data required for line transect analysis), while in the Faroese, standard line transect sampling was applied, following the SCANS-II (Small Cetacean Abundance in the North Sea) survey protocol. In both surveys, identical aircraft surveyed at an altitude of 600 ft and a speed of 90100 kn. Only data collected during Beaufort Sea States (BSS) lower than 3 and during good or moderate porpoise sighting conditions were used for abundance estimates. Abundance estimates were corrected using stratified estimates of esw (incorporating g(0)) values derived during the SCANS-II survey in 2005 as principal observers took part in this survey as well. In Iceland, realised effort in good or moderate harbour porpoise sighting conditions totalled 8,289 km in 13 survey strata, where 77 sightings (109 individuals) were made by the experienced harbour porpoise observer only. In Faroese waters, only part of the area inside the 300 m depth curve could be surveyed and 1,564 km were surveyed in good or moderate porpoise sighting conditions, yielding 39 sightings (49 individuals). The total abundance estimates were 43,179 porpoises (CV=0.45; 95% CI: 31,755161,899) for Icelandic coastal waters and 5,175 porpoises (CV=0.44; 95% CI: 3,45717,637) for Faroese waters.

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Published
2020-08-17
How to Cite
Gilles, A., Gunnlaugsson, T., Mikkelsen, B., Pike, D. G., & Víkingsson, G. (2020). Summer Abundance of Harbour Porpoises (Phocoena phocoena) in the Coastal Waters of Iceland and the Faroe Islands. NAMMCO Scientific Publications, 11. https://doi.org/10.7557/3.4939