title: Comparing Distribution of Harbour Porpoises (Phocoena phocoena) Derived from Satellite Telemetry and Passive Acoustic Monitoring.
abstract: Cetacean monitoring is essential in determining the status of a population. Different monitoring methods should reflect the real trends in abundance and patterns in distribution, and results should therefore ideally be independent of the selected method. Here, we compare two independent methods of describing harbour porpoise (Phocoena phocoena) relative distribution pattern in the western Baltic Sea. Satellite locations from 13 tagged harbour porpoises were used to build a Maximum Entropy (MaxEnt) model of suitable habitats. The data set was subsampled to one location every second day, which were sufficient to make reliable models over the summer (Jun-Aug) and autumn (Sep-Nov) seasons. The modelled results were compared to harbour porpoise acoustic activity obtained from 36 static acoustic monitoring stations (C-PODs) covering the same area. The C-POD data was expressed as the percentage of porpoise positive days/hours (the number of days/hours per day with porpoise detections) by season. The MaxEnt model and C-POD data showed a significant linear relationship with a strong decline in porpoise occurrence from west to east. This study shows that two very different methods provide comparable information on relative distribution patterns of harbour porpoises even in a low density area.
authors.affiliation: Department of Bioscience, Aarhus University, Roskilde, Denmark.
authors.forename: Lonnie
authors.identifier: http://orcid.org/0000-0002-7708-4965
authors.initials: L
authors.lastname: Mikkelsen
authors.affiliation: Department of Bioscience, Aarhus University, Roskilde, Denmark.
authors.forename: Frank F
authors.initials: FF
authors.lastname: Rigét
authors.affiliation: Department of Bioscience, Aarhus University, Roskilde, Denmark.
authors.forename: Line A
authors.initials: LA
authors.lastname: Kyhn
authors.affiliation: Department of Bioscience, Aarhus University, Roskilde, Denmark.
authors.forename: Signe
authors.initials: S
authors.lastname: Sveegaard
authors.affiliation: Department of Bioscience, Aarhus University, Roskilde, Denmark.
authors.forename: Rune
authors.initials: R
authors.lastname: Dietz
authors.affiliation: Department of Bioscience, Aarhus University, Roskilde, Denmark.
authors.forename: Jakob
authors.initials: J
authors.lastname: Tougaard
authors.affiliation: AquaBiota Water Research, Stockholm, Sweden.|Swedish Museum of Natural History, Stockholm, Sweden.
authors.forename: Julia A K
authors.initials: JA
authors.lastname: Carlström
authors.affiliation: AquaBiota Water Research, Stockholm, Sweden.|Coalition Clean Baltic, Uppsala, Sweden.
authors.forename: Ida
authors.initials: I
authors.lastname: Carlén
authors.affiliation: German Oceanographic Museum, Stralsund, Germany.|BioAcoustics Network, Stralsund, Germany.
authors.forename: Jens C
authors.initials: JC
authors.lastname: Koblitz
authors.affiliation: Department of Bioscience, Aarhus University, Roskilde, Denmark.
authors.forename: Jonas
authors.initials: J
authors.lastname: Teilmann
mesh_terms: D000162:Acoustics; D000818:Animals; D003710:Demography; D017753:Ecosystem; D004784:Environmental Monitoring / Q000379:methods*; D050741:Phocoena; D013686:Telemetry / Q000379:methods*