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Kazushi Miyashita – One of the best experts on this subject based on the ideXlab platform.

  • Spatial and temporal variation in the distribution of juvenile southern bluefin tuna Thunnus maccoyii: implication for precise estimation of recruitment abundance indices
    Fisheries Science, 2010
    Co-Authors: Ko Fujioka, Alistair J. Hobday, Ryo Kawabe, Yoshimi Takao, Kazushi Miyashita, Osamu Sakai, Tomoyuki Itoh
    Abstract:

    Acoustic tags were used to examine the spatial and temporal distribution of southern bluefin tuna (SBT) in southern Western Australia, which is in a region where fishery-independent Acoustic Surveys of the recruitment abundance index of SBT have been historically undertaken. We investigated patterns of SBT distribution within and inshore of the Acoustic Survey area during three summer seasons. Annual differences in distribution patterns were characterized by two distinctive migration pathways. An inshore-migrating pathway was observed in two seasons (2004/2005 and 2006/2007), with a relatively high proportion of tagged SBT (84.5, 65.0%) migrating inshore of the Acoustic Survey area. The other pathway was concentrated along the shelf (2005/2006 season), with an estimated 63.3% of tagged SBT moving within the Survey area. These variable migration patterns may bias the interannual fluctuations in abundance indices. Current Survey methods can be modified to include both inshore and continental shelf areas. This contribution shows that the accuracy of Acoustic Surveys can be improved by including ecological patterns.

  • correction factors derived from Acoustic tag data for a juvenile southern bluefin tuna abundance index in southernwestern australia
    , 2009
    Co-Authors: Alistair J. Hobday, Ryo Kawabe, Yoshimi Takao, Kazushi Miyashita, Tomoyuki Itoh
    Abstract:

    Juvenile southern bluefin tuna (SBT, Thunnus maccoyii), migrate down the coast of Western Australia reaching the southern coast at age-1. In these waters an Acoustic Survey for SBT schools was initiated to generate a fisheries-independent abundance index. A decline in this abundance index led to an Acoustic tagging and monitoring project to determine if a change in migration route or timing could explain the decline. Five years of Acoustic monitoring revealed interannual differences in key factors that could impact the abundance index. Acoustic tag data were used to demonstrate that (i) a high proportion of fish (~70%) may be too shallow for detection in the Acoustic Survey, and that interannual variation in (ii) inshore-offshore fraction (~30–70% each year) and (iii) residence time (12–37 days) will impact calculation of an index. These factors should be included in estimating an abundance index for SBT, together with a correction for (iv) the fraction of juvenile SBT that migrate to southern Western Australia. Collectively, these results illustrate how electronic tagging data can be used to improve understanding of abundance patterns necessary for sustainable management of this exploited species.

  • Acoustic identification of isada krill euphausia pacifica hansen off the sanriku coast north eastern japan
    Fisheries Oceanography, 1998
    Co-Authors: Kazushi Miyashita, Ichiro Aoki, Koutaro Seno, Kenji Taki, Takashi Ogishima
    Abstract:

    In this study, the feasibility of identification and abundance estimation of isada krill, Euphausia pacifica, was examined using a two-frequency (38 and 120 kHz) method. The Acoustic Survey and midwater trawling were conducted off the Sanriku coast, northern part of Honshu, Japan. In one pattern, the SV difference between the two frequencies was large, and in the other, the SV difference was small. These results were interpreted by scattering models, and showed that discrimination between isada krill and walleye pollock was possible.

P.w. Froneman – One of the best experts on this subject based on the ideXlab platform.

  • Macroplankton/micronekton dynamics in the vicinity of the Prince Edward Islands (Southern Ocean)
    Marine Biology, 1999
    Co-Authors: Evgeny A. Pakhomov, P.w. Froneman
    Abstract:

    Combined trawling (rectangular midwater trawl, RMT-8 net) and Acoustic (120 kHz) Surveys in the upstream and downstream region of the Prince Edward Islands were undertaken during April and May 1996 and 1997. A total of 49 species of macroplankton and micronekton were encountered within the region investigated. Mesopelagic fishes, euphausiids, chaetognaths and tunicates dominated numerically and by biomass. Average abundance and biomass of macroplankton/micronekton in the top 300 m layer were low, 18 individuals 1000 m−3 and 288 mg dry wt 1000 m−3, respectively. Numerical analysis revealed the presence of two major groups of stations broadly corresponding to the offshore (upstream and downstream) and inshore (inter-island) realms. Planktonic samples and Acoustic measurements revealed that elevated densities of macroplankton/micronekton were associated with the subantarctic front region and in close proximity to the island plateau. Based on trawling and Acoustic Survey results, it is suggested that large plankton and micronekton are mostly washed around rather than across the inter-island shelf region. This is in contrast with the “replenishing hypothesis” previously proposed for this region by other investigators.

  • macroplankton micronekton dynamics in the vicinity of the prince edward islands southern ocean
    Marine Biology, 1999
    Co-Authors: Evgeny A. Pakhomov, P.w. Froneman
    Abstract:

    Combined trawling (rectangular midwater trawl, RMT-8 net) and Acoustic (120 kHz) Surveys in the upstream and downstream region of the Prince Edward Islands were undertaken during April and May 1996 and 1997. A total of 49 species of macroplankton and micronekton were encountered within the region investigated. Mesopelagic fishes, euphausiids, chaetognaths and tunicates dominated numerically and by biomass. Average abundance and biomass of macroplankton/micronekton in the top 300 m layer were low, 18 individuals 1000 m−3 and 288 mg dry wt 1000 m−3, respectively. Numerical analysis revealed the presence of two major groups of stations broadly corresponding to the offshore (upstream and downstream) and inshore (inter-island) realms. Planktonic samples and Acoustic measurements revealed that elevated densities of macroplankton/micronekton were associated with the subantarctic front region and in close proximity to the island plateau. Based on trawling and Acoustic Survey results, it is suggested that large plankton and micronekton are mostly washed around rather than across the inter-island shelf region. This is in contrast with the “replenishing hypothesis” previously proposed for this region by other investigators.

Keogh N. – One of the best experts on this subject based on the ideXlab platform.

  • Blue Whiting Acoustic Survey cruise report, March 20- April 06, 2018
    O'Donnell D. Johnston G. Mullins E. Keogh N. and Power J. (2018). Blue Whiting Acoustic Survey cruise report March 20- April 06 2018. FSS Survey Serie, 2018
    Co-Authors: O'donnell D., Johnston G., Keogh N., Mullins E., Power J.
    Abstract:

    Acoustic Surveys targeting blue whiting (Micromesistius poutassou) spawning and post spawning aggregations in the north east Atlantic have been carried out by the Institute of Marine Research (IMR) Norway since the early 1970s. The 2018 Survey was part of an international collaborative Survey using the vessels RV Celtic Explorer (Ireland), RV Tridens (Netherlands), FV Kings Bay (Norway) and the RV Magnus Heinason (Faroes). The total combined area coverage extended from the Faroe Islands in the north (62° N) to south of Ireland (51° N), with east -west extension from 1°-18° W. To the south of 51°N the Spanish research vessel the RV Miguel Oliver conducted a Survey, complimentary to, but separate to the IBWSS Survey, as part of their annual PELACUS Survey program. International Survey participants met shortly after the Survey to present data and produce a combined relative abundance stock estimate and report. The combined Survey report is presented annually at the WGIPS meeting held in January. The information presented here relates specifically to the Irish Survey unless otherwise stated

  • Blue Whiting Acoustic Survey cruise report, March 19- April 11, 2017
    Marine Institute, 2017
    Co-Authors: O'donnell D., Johnston G., Keogh N., Mullins E., O'callaghan S.
    Abstract:

    Acoustic Surveys on blue whiting (Micromesistius poutassou) spawning aggregations in the north east Atlantic have been carried out by the Institute of Marine Research (IMR) Norway since the early 1970s. The 2017 Survey was part of an international collaborative Survey using the vessels RV Celtic Explorer (Ireland), RV Tridens (Netherlands), FV Kings Bay (Norway) and the RV Magnus Heinason (Faroes). The total combined area coverage extended from the Faroe Islands in the north (62° N) to south of Ireland (51° N), with east -west extension from 1°-17° W. International Survey participants meet shortly after the Survey to present data and produce a combined relative abundance stock estimate and report. The combined Survey report is presented annually at the WGIPS meeting held in January. The information presented here relates specifically to the Irish Survey

  • Blue Whiting Acoustic Survey Cruise Report, March 22 – April 01, 2015
    Marine Institute, 2015
    Co-Authors: O'donnell C., Nolan C., Johnston G., Keogh N., Van Der Knaap, Borawska A., O’donovan M.
    Abstract:

    Acoustic Surveys on blue whiting (Micromesistius poutassou) spawning aggregations in the north east Atlantic have been carried out by the Institute of Marine Research (IMR) Norway since the early 1970s. The 2015 Survey was part of an international collaborative Survey using the vessels RV Celtic Explorer (Ireland), FV Fridtjof Nansen (Russia), RV Tridens (Netherlands) and the RV Magnus Heinason (Faroes). The total combined area coverage extended from the Faroe Islands in the north (62° N) to south of Ireland (51° N), with east -west extension from 4°-18° W. International Survey participants meet shortly after the Survey to present data and produce a combined relative abundance stock estimate and report. The combined Survey report is presented annually at the WGIPS meeting held in January. The information presented here relates specifically to the Irish Survey component