title: Size Distribution of Sperm Whales Acoustically Identified during Long Term Deep-Sea Monitoring in the Ionian Sea.
abstract: The sperm whale (Physeter macrocephalus) emits a typical short acoustic signal, defined as a "click", almost continuously while diving. It is produced in different time patterns to acoustically explore the environment and communicate with conspecifics. Each emitted click has a multi-pulse structure, resulting from the production of the sound within the sperm whale's head. A Stable Inter Pulse Interval (Stable IPI) can be identified among the pulses that compose a single click. Applying specific algorithms, the measurement of this interval provides useful information to assess the total length of the animal recorded. In January 2005, a cabled hydrophone array was deployed at a depth of 2,100 m in the Central Mediterranean Sea, 25 km offshore Catania (Ionian Sea). The acoustic antenna, named OνDE (Ocean noise Detection Experiment), was in operation until November 2006. OνDE provided real time acoustic data used to perform Passive Acoustic Monitoring (PAM) of cetacean sound emissions. In this work, an innovative approach was applied to automatically measure the Stable IPI of the clicks, performing a cepstrum analysis to the energy (square amplitude) of the signals. About 2,100 five-minute recordings were processed to study the size distribution of the sperm whales detected during the OνDE long term deep-sea acoustic monitoring. Stable IPIs were measured in the range between 2.1 ms and 6.4 ms. The equations of Gordon (1991) and of Growcott (2011) were used to convert the IPIs into measures of size. The results revealed that the sperm whales recorded were distributed in length from about 7.5 m to 14 m. The size category most represented was from 9 m to 12 m (adult females or juvenile males) and specimens longer than 14 m (old males) seemed to be absent.
authors.affiliation: Dipartimento di Scienze Biologiche e Ambientali, University of Messina, Messina, Italy.|Istituto Nazionale di Fisica Nucleare (INFN)-Laboratori Nazionali del Sud, Catania, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Caruso
authors.affiliation: Dipartimento di Scienze Biologiche e Ambientali, University of Messina, Messina, Italy.|Istituto Nazionale di Fisica Nucleare (INFN)-Laboratori Nazionali del Sud, Catania, Italy.
authors.forename: Virginia
authors.initials: V
authors.lastname: Sciacca
authors.affiliation: Istituto Nazionale di Fisica Nucleare (INFN)-Laboratori Nazionali del Sud, Catania, Italy.|Dipartimento di Fisica ed Astronomia, University of Catania, Catania, Italy.
authors.forename: Giorgio
authors.initials: G
authors.lastname: Bellia
authors.affiliation: Dipartimento di Scienze Biologiche e Ambientali, University of Messina, Messina, Italy.
authors.forename: Emilio
authors.initials: E
authors.lastname: De Domenico
authors.affiliation: Istituto Nazionale di Fisica Nucleare (INFN)-Laboratori Nazionali del Sud, Catania, Italy.
authors.forename: Giuseppina
authors.initials: G
authors.lastname: Larosa
authors.affiliation: Bioacoustics Lab, IAMC Capo Granitola, National Research Council, Torretta Granitola (TP), Italy.
authors.forename: Elena
authors.initials: E
authors.lastname: Papale
authors.affiliation: Istituto Nazionale di Fisica Nucleare (INFN)-Bologna, Bologna, Italy.|Dipartimento di Fisica ed Astronomia, University of Bologna, Bologna, Italy.
authors.forename: Carmelo
authors.initials: C
authors.lastname: Pellegrino
authors.affiliation: Istituto Nazionale di Fisica Nucleare (INFN)-Laboratori Nazionali del Sud, Catania, Italy.
authors.forename: Sara
authors.initials: S
authors.lastname: Pulvirenti
authors.affiliation: Istituto Nazionale di Fisica Nucleare (INFN)-Laboratori Nazionali del Sud, Catania, Italy.
authors.forename: Giorgio
authors.initials: G
authors.lastname: Riccobene
authors.affiliation: Istituto Nazionale di Fisica Nucleare (INFN)-Roma1, Roma, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Simeone
authors.affiliation: Istituto Nazionale di Fisica Nucleare (INFN)-Laboratori Nazionali del Sud, Catania, Italy.
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Speziale
authors.affiliation: Istituto Nazionale di Fisica Nucleare (INFN)-Laboratori Nazionali del Sud, Catania, Italy.
authors.forename: Salvatore
authors.initials: S
authors.lastname: Viola
authors.affiliation: Centro Interdisciplinare di Bioacustica e Ricerche Ambientali (CIBRA), Dipartimento di Scienze della Terra e dell'Ambiente, University of Pavia, Pavia, Italy.
authors.forename: Gianni
authors.initials: G
authors.lastname: Pavan
mesh_terms: D000162:Acoustics; D000818:Animals; D049628:Body Size; D008522:Mediterranean Sea; D011157:Population Dynamics; D058998:Remote Sensing Technology; D050661:Sperm Whale; D014828:Vocalization, Animal