title: Effects of subsampling of passive acoustic recordings on acoustic metrics.
abstract: Passive acoustic monitoring is an important tool in marine mammal studies. However, logistics and finances frequently constrain the number and servicing schedules of acoustic recorders, requiring a trade-off between deployment periods and sampling continuity, i.e., the implementation of a subsampling scheme. Optimizing such schemes to each project's specific research questions is desirable. This study investigates the impact of subsampling on the accuracy of two common metrics, acoustic presence and call rate, for different vocalization patterns (regimes) of baleen whales: (1) variable vocal activity, (2) vocalizations organized in song bouts, and (3) vocal activity with diel patterns. To this end, above metrics are compared for continuous and subsampled data subject to different sampling strategies, covering duty cycles between 50% and 2%. The results show that a reduction of the duty cycle impacts negatively on the accuracy of both acoustic presence and call rate estimates. For a given duty cycle, frequent short listening periods improve accuracy of daily acoustic presence estimates over few long listening periods. Overall, subsampling effects are most pronounced for low and/or temporally clustered vocal activity. These findings illustrate the importance of informed decisions when applying subsampling strategies to passive acoustic recordings or analyses for a given target species.
authors.affiliation: Ocean Acoustics Lab, Alfred-Wegener-Institut Helmholtz Zentrum für Polar- und Meeresforschung, 27570 Bremerhaven, Germany.
authors.forename: Karolin
authors.initials: K
authors.lastname: Thomisch
authors.affiliation: Ocean Acoustics Lab, Alfred-Wegener-Institut Helmholtz Zentrum für Polar- und Meeresforschung, 27570 Bremerhaven, Germany.
authors.forename: Olaf
authors.initials: O
authors.lastname: Boebel
authors.affiliation: Ocean Acoustics Lab, Alfred-Wegener-Institut Helmholtz Zentrum für Polar- und Meeresforschung, 27570 Bremerhaven, Germany.
authors.forename: Daniel P
authors.initials: DP
authors.lastname: Zitterbart
authors.affiliation: Observatoire PELAGIS CNRS-UMS 3462, University of La Rochelle, 17000 La Rochelle, France.
authors.forename: Flore
authors.initials: F
authors.lastname: Samaran
authors.affiliation: Northeast Fisheries Science Center, 166 Water Street, Woods Hole, Massachusetts 02543, USA.
authors.forename: Sofie
authors.initials: S
authors.lastname: Van Parijs
authors.affiliation: Ocean Acoustics Lab, Alfred-Wegener-Institut Helmholtz Zentrum für Polar- und Meeresforschung, 27570 Bremerhaven, Germany.
authors.forename: Ilse
authors.initials: I
authors.lastname: Van Opzeeland
mesh_terms: D000162:Acoustics; D063147:Animal Distribution; D000818:Animals; D008386:Marine Biology / Q000379:methods*; D011156:Population Density; D011336:Probability; D012494:Sampling Studies; D013018:Sound Spectrography; D013997:Time Factors; D014828:Vocalization, Animal; D014907:Whales / Q000502:physiology*