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  • Acoustics  (2)
  • Bueguela Current Comission  (1)
  • Institute of Electrical and Electronics Engineers (IEEE)
  • Public Library of Science
  • Springer Science + Business Media
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Years
  • 1
    Publication Date: 2017-04-04
    Description: In recent years, an increasing number of surveys have definitively confirmed the seasonal presence of fin whales (Balaenoptera physalus) in highly productive regions of the Mediterranean Sea. Despite this, very little is yet known about the routes that the species seasonally follows within the Mediterranean basin and, particularly, in the Ionian area. The present study assesses for the first time fin whale acoustic presence offshore Eastern Sicily (Ionian Sea), throughout the processing of about 10 months of continuous acoustic monitoring. The recording of fin whale vocalizations was made possible by the cabled deep-sea multidisciplinary observatory, “NEMO-SN1”, deployed 25 km off the Catania harbor at a depth of about 2,100 meters. NEMO-SN1 is an operational node of the European Multidisciplinary Seafloor and water-column Observatory (EMSO) Research Infrastructure. The observatory was equipped with a low-frequency hydrophone (bandwidth: 0.05 Hz–1 kHz, sampling rate: 2 kHz) which continuously acquired data from July 2012 to May 2013. About 7,200 hours of acoustic data were analyzed by means of spectrogram display. Calls with the typical structure and patterns associated to the Mediterranean fin whale population were identified and monitored in the area for the first time. Furthermore, a background noise analysis within the fin whale communication frequency band (17.9–22.5 Hz) was conducted to investigate possible detection-masking effects. The study confirms the hypothesis that fin whales are present in the Ionian Sea throughout all seasons, with peaks in call detection rate during spring and summer months. The analysis also demonstrates that calls were more frequently detected in low background noise conditions. Further analysis will be performed to understand whether observed levels of noise limit the acoustic detection of the fin whales vocalizations, or whether the animals vocalize less in the presence of high background noise.
    Description: Published
    Description: e0141838
    Description: 3A. Ambiente Marino
    Description: JCR Journal
    Description: open
    Keywords: Whales ; Bioacoustics ; Background noise (acoustics) ; Acoustic signals ; Sperm whales ; Vocalization ; Acoustics ; Data acquisition ; 03. Hydrosphere::03.01. General::03.01.08. Instruments and techniques ; 03. Hydrosphere::03.02. Hydrology::03.02.04. Measurements and monitoring ; 03. Hydrosphere::03.02. Hydrology::03.02.07. Instruments and techniques ; 03. Hydrosphere::03.04. Chemical and biological::03.04.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 2
    Publication Date: 2021-05-19
    Description: The main objectives of the survey were the following: • To map the distribution and estimate the abundance of the most commercially important pelagic species in the Namibia-Angola transboundary area (15°50-19°00’), following the survey design utilized in Angolan waters (6 n.mi spacing between transect lines), with special emphasis on the two horse mackerel Cunene horse mackerel (Trachurus trecae) and Cape horse mackerel (Trachurus capensis), sardine “Pilchard” (Sardinops sagax) and other small pelagic species, including anchovy (Engraulis capensis) and round herring (Etrumeus whiteheadi). • To map the distributions and estimate the abundance of the same species in central Namibia south to Dune Point (20°15’ S), following the established survey design with 10 n.mi spacing between the transect lines. • To study and analyse the biological state of the main species, including length frequencies, length-weight relationships, reproductive stages and length-at-maturity. • To map the meteorological and hydrographical conditions in the survey area by means of continuous recordings of weather data such as Sea-surface temperature (SST), Seasurface salinity (SSS), wind
    Description: BCC PROJECT: LMR/NANSEN/1/10 CRUISE REPORTS “DR. FRIDTJOF NANSEN”1) Institute of Marine Research, Bergen, Norway 2) Instituto Nacional de Investigação Pesqueira, Luanda, Angola 3) National Marine Information and Research Centre, Swakopmund, Namibia
    Description: Published
    Description: Northernern Namibia
    Description: Transboundary area
    Description: Trawl sampling procedures
    Description: Acoustical sampling
    Description: Survey grid
    Description: Meteorological sampling
    Description: hydrographical sampling
    Description: Oceanographic conditions
    Description: Transboundary area
    Keywords: Pelagic fisheries ; Fishery surveys ; Acoustics ; Sampling ; Trawls ; Oceanography ; Biomass ; Distribution ; Composition
    Repository Name: AquaDocs
    Type: Report , Non-Refereed
    Format: 46
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