Distribution of humpback whales in Skjálfandi Bay, Iceland
The populations of Megaptera novaeangliae are increasing again after commercial whaling, which strongly decimated the number of individuals, was stopped in the mid-20th century. Humpback whales are among the most common whale species occurring in Skjálfandi Bay, North Iceland. The present data show increasing sighting rates during the summer research season (April - October) from 2003 (0.0001/minute) to 2012 (0.0246/minute), whereas no significant variations in sighting frequencies between different months were reported. Sighting rates as well as distribution patterns within Skjálfandi Bay, however, fluctuated between the years. Since 2001, photographed humpback whales in Skjálfandi Bay have been identified and cataloged. The resighting rate was always less than 27 % in the bay. A total of 77 humpback whales were identified during the 2012 summer research season, including 11 resightings. Only few individuals returned to Skjálfandi Bay for several years, indicating that the humpback whales occurring here belong to a bigger population with various feeding areas around Iceland. We interpret the increase in sightings to reflect enhanced feeding conditions within the bay, raising the potential for whale watching operations. This study also supports the efforts to integrate whale watching vessels as platforms of opportunity for cetacean research.