Site specific passive acoustic detection and densities of humpback whale calls off the coast of California
Passive acoustic monitoring of marine mammal calls is an increasingly important method for assessing population numbers, distribution, and behavior. Automated methods are needed to aid in the analyses of the recorded data. When a mammal vocalizes in the marine environment, the received signal is a f...
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ftcdlib:oai:escholarship.org/ark:/13030/qt7615x5dw 2023-05-15T16:35:56+02:00 Site specific passive acoustic detection and densities of humpback whale calls off the coast of California Helble, Tyler Adam 2013-01-01 application/pdf https://escholarship.org/uc/item/7615x5dw unknown eScholarship, University of California qt7615x5dw https://escholarship.org/uc/item/7615x5dw public UCSD Oceanography. (Discipline) Dissertations Academic etd 2013 ftcdlib 2020-06-06T07:56:06Z Passive acoustic monitoring of marine mammal calls is an increasingly important method for assessing population numbers, distribution, and behavior. Automated methods are needed to aid in the analyses of the recorded data. When a mammal vocalizes in the marine environment, the received signal is a filtered version of the original waveform emitted by the marine mammal. The waveform is reduced in amplitude and distorted due to propagation effects that are influenced by the bathymetry and environment. It is important to account for these effects to determine a site -specific probability of detection for marine mammal calls in a given study area. A knowledge of that probability function over a range of environmental and ocean noise conditions allows vocalization statistics from recordings of single, fixed, omnidirectional sensors to be compared across sensors and at the same sensor over time with less bias and uncertainty in the results than direct comparison of the raw statistics. This dissertation focuses on both the development of new tools needed to automatically detect humpback whale vocalizations from single-fixed omnidirectional sensors as well as the determination of the site-specific probability of detection for monitoring sites off the coast of California. Using these tools, detected humpback calls are "calibrated" for environmental properties using the site-specific probability of detection values, and presented as call densities (calls per square kilometer per time). A two-year monitoring effort using these calibrated call densities reveals important biological and ecological information on migrating humpback whales off the coast of California. Call density trends are compared between the monitoring sites and at the same monitoring site over time. Call densities also are compared to several natural and human- influenced variables including season, time of day, lunar illumination, and ocean noise. The results reveal substantial differences in call densities between the two sites which were not noticeable using uncorrected (raw) call counts. Additionally, a Lombard effect was observed for humpback whale vocalizations in response to increasing ocean noise. The results presented in this thesis develop techniques to accurately measure marine mammal abundances from passive acoustic sensors Other/Unknown Material Humpback Whale University of California: eScholarship Lombard ENVELOPE(-59.686,-59.686,-64.520,-64.520) |
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UCSD Oceanography. (Discipline) Dissertations Academic |
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UCSD Oceanography. (Discipline) Dissertations Academic Helble, Tyler Adam Site specific passive acoustic detection and densities of humpback whale calls off the coast of California |
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UCSD Oceanography. (Discipline) Dissertations Academic |
description |
Passive acoustic monitoring of marine mammal calls is an increasingly important method for assessing population numbers, distribution, and behavior. Automated methods are needed to aid in the analyses of the recorded data. When a mammal vocalizes in the marine environment, the received signal is a filtered version of the original waveform emitted by the marine mammal. The waveform is reduced in amplitude and distorted due to propagation effects that are influenced by the bathymetry and environment. It is important to account for these effects to determine a site -specific probability of detection for marine mammal calls in a given study area. A knowledge of that probability function over a range of environmental and ocean noise conditions allows vocalization statistics from recordings of single, fixed, omnidirectional sensors to be compared across sensors and at the same sensor over time with less bias and uncertainty in the results than direct comparison of the raw statistics. This dissertation focuses on both the development of new tools needed to automatically detect humpback whale vocalizations from single-fixed omnidirectional sensors as well as the determination of the site-specific probability of detection for monitoring sites off the coast of California. Using these tools, detected humpback calls are "calibrated" for environmental properties using the site-specific probability of detection values, and presented as call densities (calls per square kilometer per time). A two-year monitoring effort using these calibrated call densities reveals important biological and ecological information on migrating humpback whales off the coast of California. Call density trends are compared between the monitoring sites and at the same monitoring site over time. Call densities also are compared to several natural and human- influenced variables including season, time of day, lunar illumination, and ocean noise. The results reveal substantial differences in call densities between the two sites which were not noticeable using uncorrected (raw) call counts. Additionally, a Lombard effect was observed for humpback whale vocalizations in response to increasing ocean noise. The results presented in this thesis develop techniques to accurately measure marine mammal abundances from passive acoustic sensors |
format |
Other/Unknown Material |
author |
Helble, Tyler Adam |
author_facet |
Helble, Tyler Adam |
author_sort |
Helble, Tyler Adam |
title |
Site specific passive acoustic detection and densities of humpback whale calls off the coast of California |
title_short |
Site specific passive acoustic detection and densities of humpback whale calls off the coast of California |
title_full |
Site specific passive acoustic detection and densities of humpback whale calls off the coast of California |
title_fullStr |
Site specific passive acoustic detection and densities of humpback whale calls off the coast of California |
title_full_unstemmed |
Site specific passive acoustic detection and densities of humpback whale calls off the coast of California |
title_sort |
site specific passive acoustic detection and densities of humpback whale calls off the coast of california |
publisher |
eScholarship, University of California |
publishDate |
2013 |
url |
https://escholarship.org/uc/item/7615x5dw |
long_lat |
ENVELOPE(-59.686,-59.686,-64.520,-64.520) |
geographic |
Lombard |
geographic_facet |
Lombard |
genre |
Humpback Whale |
genre_facet |
Humpback Whale |
op_relation |
qt7615x5dw https://escholarship.org/uc/item/7615x5dw |
op_rights |
public |
_version_ |
1766026245801246720 |