Premium
Passive acoustic density estimation of sperm whales in the Tongue of the Ocean, Bahamas
Author(s) -
W ard Jessica A.,
Thomas Len,
Jarvis Susan,
DiMarzio Nancy,
Moretti David,
Marques Tiago A.,
Dunn Charlotte,
C laridge Diane,
Hartvig Eva,
Tyack Peter
Publication year - 2012
Publication title -
marine mammal science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.723
H-Index - 78
eISSN - 1748-7692
pISSN - 0824-0469
DOI - 10.1111/j.1748-7692.2011.00560.x
Subject(s) - sperm whale , hydrophone , cetacea , sonar , range (aeronautics) , whale , biology , bioacoustics , oceanography , baleen , sperm , fishery , acoustics , geology , engineering , biochemistry , physics , botany , myoglobin , aerospace engineering
Long‐term passive acoustic monitoring of marine mammals on navy ranges provides the opportunity to better understand the potential impact of sonar on populations. The navy range in Tongue of the Ocean (TOTO), Bahamas contains extensive hydrophone arrays, potentially allowing estimation of the density of deep diving, vocally active species such as the sperm whale ( Physeter macrocephalus ). Previous visual surveys in TOTO have been of limited spatio–temporal coverage and resulted in only sporadic sightings of sperm whales, whereas passive acoustic observations suggest the species is present year round. However, until now the means of acoustically determining the specific number of individuals in each cluster has been limited. We used recently developed algorithms to identify the number of echolocating whales present during a 42 d study period. We screened a 297 h acoustic data set to determine the proportion of time animals were present; fifty 10 min samples during presence were analyzed to estimate the number of individuals vocalizing during each sample. These counts were combined with an independent estimate of the proportion of 10 min periods when tagged animals vocalize. The estimated average density was 0.16 whales/1,000 km 2 (CV 27%; 95% CI 0.095–0.264). The method is potentially applicable to other areas containing dense hydrophone arrays.