リモートセンシングを用いた南太平洋西部におけるイワシクジラと海洋環境との関係  [in Japanese] Remote Sensing Based Observation of Ocean Conditions and Their Influence on The Sei Whale Distribution in The Western South Pacific  [in Japanese]

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Abstract

南半球におけるイワシクジラは、他のヒゲクジラ類と同様、冬は低緯度海域で繁殖し夏に高緯度海域で摂餌といった季節回遊を行う。高い回遊能力を持つ鯨類の調査には広域的かつ継続的な観測が必要不可欠である。本研究では人工衛星によるリモートセンシングを利用し、南極海鯨類捕獲調査(JARPA)において同種が発見された周辺海域の海洋環境を解明する事を目的とした。同種の主な餌生物はコペポーダ等、低次の動物プランクトンであり、多くの鯨類の中でも海洋環境との関係が深いと考えられるため、人工衛星の利点を十分に生かした研究が出来ると期待される。2000年及び2002年の目視情報に基づき西部南太平洋(南緯20~60度、東経170~西経160度)を対象とし、水温、水温勾配・クロロフィル-a濃度、海底地形等のパラメータを解析した結果、同種が発見された海域は主に海底斜面域で周囲よりクロロフィル-a濃度の高い海域である事が分かった。同種の発見に最も影響を与えていたのは水温であり同種の発見が集中していた水温帯は夏季の亜熱帯前線の指標となる水温帯と一致し、同種と亜熱帯前線との間に強い関係がある事が示唆された。

Like other baleen whales, the Sei Whales of the southern hemisphere undertake seasonal migration toward high-latitude feeding grounds in the summer and toward low-latitude breeding grounds in the winter. They are highly migratory with wide oceanic distribution ; hence spatial and temporal scale observations are necessary to understand their distribution pattern. Under this investigation we used satellite derived ocean parameters and the whale sighting location data collected under the Japanese Whale Research Program under Special Permit in the Antarctic (JARPA) in order to elucidate prevalent ocean condition where whale sighting was undertaken, and to understand its influence on the distribution of the Sei Whales. The Sei Whales mostly feed on the low level zooplankton such as copepods and copepods feed on the phytoplankton. Due to such trophic relationship the Sei Whales are closely associated with the pelagic ocean environment which can be advantageously monitored by remote sensing observation. The present study was carried out using the whale sighting location data in the western South Pacific (20°-60°S,170°E-160°W) in 2000 and 2002 along with the satellite derived ocean parameters such as sea surface temperature (SST), SST gradient, chlorophyll-a concentration as well as the sea bottom topography to understand the relative impact of the ocean parameters on the distribution of the Sei Whales. The whale sighting locations were found to coincide mostly with the ocean areas with high chlorophyll-a concentration as well as the high topography gradient. We coined an index for the characteristic SST of the whale sighting locations and named as favorable temperature index (FTI). Statistically strongest relationship was noticed between the FTI and the whale sighting locations. Our FTI coincided with that of the SST of sub-tropical frontal waters. Such results clearly indicate major influence of the sub-tropical front on the distribution of the Sei Whales in the western South Pacific.

Journal

  • 東海大学紀要. 海洋学部

    東海大学紀要. 海洋学部 3(3), 1-12, 2006-03

    The School of Marine Science and Technology, Tokai University

Codes

  • NII Article ID (NAID)
    120005719425
  • NII NACSIS-CAT ID (NCID)
    AN00157043
  • Text Lang
    JPN
  • Article Type
    journal article
  • ISSN
    1348-7620
  • Data Source
    IR  JASI 
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