Dominique Weilermann’s scientific contributions

The Northern bottlenose whale (Hyperoodon ampullatus) is a deep-diving species that belongs to the family Ziphiidae. This species can reach up to 9.5 meters in length and is distributed in the North Atlantic ocean, preferring cold waters. Very little is known about this species, except for a well-studied population appearing at the Gully, an underwater canyon off Nova Scottia, Canada. This population has been monitored since 1988 and consists of about 160 identified individuals. To date, nothing has been published about bottlenose whales sighted around the Azorean archipelago. Here we present the first catalogue of the individuals off Pico Ilsand based on photo-ID techniques. We had 36 boat-based group encounters from 2003 to 2009 (except in 2004) occurring during July and August. The group size varied between 3 and 26 individuals. A total of 14460 pictures were taken, of which 5784 were chosen for analyses and only pictures with Q>3 were selected for the catalogue. Based on several identification markings on the dorsal fin and body such as notches, spots, scratches and coloration patterns, we were able to identify 135 individuals (61 both sides + 74 left side). One resighting was found between years, seen first in 2003 and later in 2008. The individuals spend between 1 and 13 days in the area. We believe the number of animals that appear in the study area could be significantly higher since there are 53 animals identified only on the right side, and many individuals were impossible to photograph during the surveys. In the future, matching with other catalogues is necessary in order to know more about their migratory behaviour.

The Azorean archipelago is characterized by deep coastal waters, hence it is possible to observe deep diving cetaceans close to shore, such as sperm whales, northern bottlenose whales, Sowerby's and other beaked whales. The aim of the present study was to determine the temporal and spatial distribution of Hyperoodon ampullatus of Pico Island, Azores. The analyses were based on data gathered from 2003 to 2009, using both land and boat-based surveys. A total of 87 groups were recorded, distributed over 33 days, ranging from 1 to 11 days a year. Most of the observations were made in the summer, from mid July to the beginning of August, with 2 additional sightings at the end of August and September. They were observed mainly in the morning (63% of all observations), between 7:30 and 12:00 am. Their spatial distribution ranges from 38º18 to 38º23 N and from 28º02 to 28º27 W, which correlates with an area of 400 to 1200 m deep. Using photo-ID, we encountered resightings of different individuals both within the day and within the year. We conclude that H. ampullatus is a regular migratory species of the Azorean archipelago and probably spends more time in the sea surrounding the islands, thus we believe it is necessary to obtain more data, by collaboration with researchers from other islands in order to achieve a better understanding on species' habitat use in the Azores.