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39 results on '"Giorli, Giacomo"'

3. Studying the Biosonar Activities of Deep Diving Odontocetes in Hawaii and Other Western Pacific Locations

Author

Au, Whitlow W. L., Giorli, Giacomo, Ando, Yoichi, Series editor, Hartmann, William M., Editor-in-chief, Au, Whitlow W. L., Series editor, Baggeroer, Arthur B., Series editor, Fletcher, Neville H., Series editor, Fuller, Christopher, Series editor, Kuperman, William A., Series editor, Miller, Joanne L., Series editor, Tolstoy, Alexandra I., Series editor, and Lammers, Marc O., editor

Published
2016
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13. Seasonal Distribution of the Fin Whale (Balaenoptera physalus) in Antarctic and Australian Waters Based on Passive Acoustics

Author

Aulich, Meghan G., Mccauley, Robert D., Miller, Brian S., Samaran, Flore, Giorli, Giacomo, Saunders, Benjamin J., Erbe, Christine, Aulich, Meghan G., Mccauley, Robert D., Miller, Brian S., Samaran, Flore, Giorli, Giacomo, Saunders, Benjamin J., and Erbe, Christine

Abstract

The fin whale is listed as globally vulnerable, with ongoing threats to their population, yet little is known about the distribution and movements of the Southern Hemisphere sub-species, Balaenoptera physalus quoyi. This study assesses fin whale distribution in the Southern Hemisphere analysing acoustic recordings from 15 locations in Antarctic and Australian waters from 2002 to 2019. A seasonal acoustic presence of fin whales in Antarctic waters from late austral summer to autumn (February to June) with long-term, consistent annual usage areas was identified at the Southern Kerguelen Plateau and Dumont d’Urville sites. In comparison, limited vocal presence of fin whales was observed at the Casey site. In Australian waters, fin whales were seasonally present from austral autumn to mid-spring (May to October) on east and west coasts, with a decadal pattern of acoustic presence observed at Cape Leeuwin, WA. Two migratory pathways are identified, from the Indian sector of Antarctica to the west coast of Australia and from the Pacific sector of Antarctica to the east coast of Australia. The identified seasonal distributions and migratory pathways provide valuable information to aid in monitoring the recovery of this vulnerable sub-species. We suggest the identified distribution and dispersal from the Southern Kerguelen Plateau and Dumont d’Urville sites to the west and east coasts of Australia respectively, as well as the spatial separation between Antarctic sites, provide preliminary evidence of separate sub-populations of the Southern Hemisphere sub-species of fin whale.

Published
2022
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18. Developing an Integrated Ocean Observing System for New Zealand

Author

O’Callaghan, Joanne, primary, Stevens, Craig, additional, Roughan, Moninya, additional, Cornelisen, Chris, additional, Sutton, Philip, additional, Garrett, Sally, additional, Giorli, Giacomo, additional, Smith, Robert O., additional, Currie, Kim I., additional, Suanda, Sutara H., additional, Williams, Michael, additional, Bowen, Melissa, additional, Fernandez, Denise, additional, Vennell, Ross, additional, Knight, Benjamin R., additional, Barter, Paul, additional, McComb, Peter, additional, Oliver, Megan, additional, Livingston, Mary, additional, Tellier, Pierre, additional, Meissner, Anna, additional, Brewer, Mike, additional, Gall, Mark, additional, Nodder, Scott D., additional, Decima, Moira, additional, Souza, Joao, additional, Forcén-Vazquez, Aitana, additional, Gardiner, Sarah, additional, Paul-Burke, Kura, additional, Chiswell, Stephen, additional, Roberts, Jim, additional, Hayden, Barb, additional, Biggs, Barry, additional, and Macdonald, Helen, additional

Published
2019
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20. Acoustically estimated size distribution of sperm whales (Physeter macrocephalus) off the east coast of New Zealand.

Author

Giorli, Giacomo and Goetz, Kimberly T.

Subjects
*SPERM whale, *CEPSTRUM analysis (Mechanics), *TRANSMISSION of sound, *BODY size, *LENGTH measurement, *WHALES
Abstract

The length-frequency distribution of sperm whales (Physeter macrocephalus) was studied on the east coast of NZ using passive acoustic recorders moored offshore of Kaikoura, Cape Palliser and Castlepoint. Sperm whale's echolocation signals are unique among odontocete species. Their clicks are composed by multiple pulses resulting from the sound transmission within the whale head. The total length of the whales can be estimated by measuring the time delay between these pulses. A total of 997 length measurements were obtained from click trains using cepstral analysis (mean = 14.6 m; min = 9.6 m; max = 18.3 m; std = 1 m). The size-frequency distributions at all three locations were similar, although animals smaller than 12 m were not present offshore of Kaikoura. Animals of various sizes appeared to be present all year round, with no apparent seasonality in the occurrence of any size class. [ABSTRACT FROM AUTHOR]

Published
2020
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39. Deep Diving Odontocetes Foraging Strategies and Their Prey Field as Determined by Acoustic Techniques

Author

Giorli, Giacomo

Abstract

Deep diving odontocetes, like sperm whales, beaked whales, Risso's dolphins, and pilot whales are known to forage at deep depths in the ocean on squid and fish. These marine mammal species are top predators and for this reason are very important for the ecosystems they live in, since they can affect prey populations and control food web dynamics through top-down effects. The studies presented in this thesis investigate deep diving odontocetes‟ foraging strategies, and the density and size of their potential prey in the deep ocean using passive and active acoustic techniques. Ecological Acoustic Recorders (EAR) were used to monitor the foraging activity of deep diving odontocetes at three locations around the world: the Josephine Seamount High Sea Marine Protected Area (JHSMPA), the Ligurian Sea, and along the Kona coast of the island of Hawaii. In the JHSMPA, sperm whales‟ and beaked whales‟ foraging rates do not differ between night-time and day-time. However, in the Ligurian Sea, sperm whales switch to night-time foraging as the winter approaches, while beaked whales alternate between hunting mainly at night, and both at night and at day. Spatial differences were found in deep diving odontocetes‟ foraging activity in Hawaii where they forage most in areas with higher chlorophyll concentrations. Pilot whales (and false killer whales, clustered together in the category "blackfishes") and Risso's dolphins forage mainly at night at all locations. These two species adjust their foraging activity with the length of the night. The density and size of animals living in deep sea scattering layers was studied using a DIDSON imaging sonar at multiple stations along the Kona coast of Hawaii. The density of animals was affected by location, depth, month, and the time of day. The size of animals was influenced by station and month. The DIDSON proved to be a successful, non-invasive technique to study density and size of animals in the deep sea. Densities were found to be an order of magnitude higher than previously found with trawls, and sizes of animals were found to be 3-4 times larger than in trawl data.

Published
2015

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