title: Using line acceleration to measure false killer whale (Pseudorca crassidens) click and whistle source levels during pelagic longline depredation.
abstract: False killer whales (Pseudorca crassidens) depredate pelagic longlines in offshore Hawaiian waters. On January 28, 2015 a depredation event was recorded 14 m from an integrated GoPro camera, hydrophone, and accelerometer, revealing that false killer whales depredate bait and generate clicks and whistles under good visibility conditions. The act of plucking bait off a hook generated a distinctive 15 Hz line vibration. Two similar line vibrations detected at earlier times permitted the animal's range and thus signal source levels to be estimated over a 25-min window. Peak power spectral density source levels for whistles (4-8 kHz) were estimated to be between 115 and 130 dB re 1 μPa2/Hz @ 1 m. Echolocation click source levels over 17-32 kHz bandwidth reached 205 dB re 1 μPa @ 1 m pk-pk, or 190 dB re 1 μPa @ 1 m (root-mean-square). Predicted detection ranges of the most intense whistles are 10 to 25 km at respective sea states of 4 and 1, with click detection ranges being 5 times smaller than whistles. These detection range analyses provide insight into how passive acoustic monitoring might be used to both quantify and avoid depredation encounters.
authors.affiliation: Marine Physical Laboratory, Scripps Institution of Oceanography, University of California San Diego, La Jolla, California 92093-0238, USA.
authors.forename: Aaron
authors.initials: A
authors.lastname: Thode
authors.affiliation: Sitka Sound Science Center, 8340 Lincoln Street, Sitka, Alaska 99835, USA.
authors.forename: Lauren
authors.initials: L
authors.lastname: Wild
authors.affiliation: University of Alaska Southeast, 1332 Seward Avenue, Sitka, Alaska 99835, USA.
authors.forename: Janice
authors.initials: J
authors.lastname: Straley
authors.affiliation: National Oceanic and Atmospheric Administration Fisheries Pacific Islands Regional Office Observer Program, 1845 Wasp Boulevard, Building 176, Honolulu, Hawaii 96818, USA.
authors.forename: Dustin
authors.initials: D
authors.lastname: Barnes
authors.affiliation: Joint Institute for Marine & Atmospheric Research, University of Hawaii at Manoa, affiliated with National Oceanic and Atmospheric Administration Fisheries Pacific Islands Fisheries Science Center, 1845 Wasp Boulevard, Building 176, Honolulu, Hawaii 96818, USA.
authors.forename: Ali
authors.initials: A
authors.lastname: Bayless
authors.affiliation: Sitka Sound Science Center, 8340 Lincoln Street, Sitka, Alaska 99835, USA.
authors.forename: Victoria
authors.initials: V
authors.lastname: O'Connell
authors.affiliation: National Oceanic and Atmospheric Administration Fisheries Pacific Islands Fisheries Science Center, 1845 Wasp Boulevard, Building 176, Honolulu, Hawaii 96818, USA.
authors.forename: Erin
authors.initials: E
authors.lastname: Oleson
authors.affiliation: Marine Physical Laboratory, Scripps Institution of Oceanography, University of California San Diego, La Jolla, California 92093-0238, USA.
authors.forename: Jit
authors.initials: J
authors.lastname: Sarkar
authors.affiliation: Alaska Longline Fishermen's Association, P.O. Box 1229, Sitka, Alaska 99835, USA.
authors.forename: Dan
authors.initials: D
authors.lastname: Falvey
authors.affiliation: Alaska Longline Fishermen's Association, P.O. Box 1229, Sitka, Alaska 99835, USA.
authors.forename: Linda
authors.initials: L
authors.lastname: Behnken
authors.affiliation: POP Fishing & Marine, 1133 North Nimitz Highway, Honolulu, Hawaii 96817, USA.
authors.forename: Sean
authors.initials: S
authors.lastname: Martin