JA/J05/JR11 Results of the cetacean prey survey using echo sounder in JARPA from 1998/99 to 2002/2003

• Main Authors: Hiroto Murase, Shigetoshi Nishiwaki, Hajime Ishikawa, Koji Matsuoka
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Antarctic; The Antarctic; Antarc*; baleen whale
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.463.9110; http://www.icrwhale.org/pdf/JA-J05-JR11.pdf

Krill biomass estimation surveys using quantitative echo sounder have been conducted in JARPA since 1998/99 season to achieve one of the main objectives of JARPA which is elucidation of the role of whales in the Antarctic marine ecosystem. The survey was conducted concurrently with cetacean survey. Similar biomass estimates were obtained in Area IV in 1999/2000 (36.4 million t) and 2001/2002 (36.1 million t) season. In Area V, biomass in 2000/2001 (18.7 million t) and in 2002/2003 (21.0 million t) were similar but biomass in 1998/1999 (32.3 million t) was higher than rest of two years. Higher biomass in 1998/99 could be explained by seasonal effect and area coverage difference. Biomass in Area IV was higher than Area V. Regional krill distribution pattern difference in response to the southerly shift of the SB-ACC was observed in Area IV. Because krill biomass survey in whole Area IV and Area V were rarely conducted in the past, krill data collected by JARPA were quite important to understand krill-baleen whale relationship in the Antarctic.