著者

Daiki Inamori Motoi Yoshioka Hidehiro Kato

出版者

Publication Committee for Cetacean Population Studies

雑誌

鯨類資源研究 (ISSN:24345571)

巻号頁・発行日

pp.2023O001, (Released:2023-03-29)

参考文献数

1

著者

Hiroto Murase Koji Matsuoka Kazuyoshi Watanabe

出版者

Publication Committee for Cetacean Population Studies

雑誌

鯨類資源研究 (ISSN:24345571)

巻号頁・発行日

pp.2022F001, (Released:2022-10-25)

参考文献数

52

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The relationships between oceanographic conditions and the distribution of common minke whales off southeastern Hokkaido was investigated in this study. Sighting surveys of common minke whales in this region were conducted in September, in 2002 and from 2004 to 2006. The density index (DI, the number of schools per 100 n.miles) of the whales decreased from 5.6 schools in 2002 to 1.2 schools in 2006. During the 4 years in which surveys were conducted, the monthly mean sea surface temperature (SST) in the survey area increased from 16.6°C in 2002 to 19.5°C in 2006, while the mean SST recorded at sighting locations was 15.5°C. The proportions of surveyed areas with a monthly mean SST ≤16°C in 2002 and 2004 were 46.5% and 17.0% respectively, whereas in 2005 and 2006, none of these areas had a monthly mean SST of less than 16°C. Pacific saury are among the major prey items of the minke whales in this region, and the number of the fishing boats was used as an indicator of the presence of the species in the surveyed area. The 4 year mean SST at the locations of the boats was 15.1°C. A reduction in the local abundance of the saury from 2002 to 2006 was inferred from the number of the boats operating in the region. These findings suggested that the apparent decline in the abundance of whales in the study area was associated with changes in SST and the availability of Pacific saury.

著者

Kenji Konishi Tsutomu Tamura

出版者

Publication Committee for Cetacean Population Studies

雑誌

鯨類資源研究 (ISSN:24345571)

巻号頁・発行日

pp.2020S006, (Released:2021-10-20)

参考文献数

11

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The energetic condition of whales is an important information to understand their energy demand to sustain their migration and reproductive success. However, basic energetic information based on biochemical components (protein, lipid, sugar, and water) and calorimetric data are limited, particularly in small baleen whales such as the minke whale. This study reports the biochemical components of the muscle tissues of 61 Antarctic minke whales (Balaenoptera bonaerensis) of different sexes and sexual maturity using near-infrared (NIR) spectroscopy. Prior to sample analysis, a calibration curve based on a standard chemical analysis was installed in the NIR analytical equipment. The dorsal muscle tissues from Antarctic minke whales contain approximately 0.5%–0.6% lipid, 26% protein, and 73% water, suggesting that the dorsal muscle contains a small amount of lipid and a high proportion of water. These proportions were similar between sexes and sexual classes. The proportions of lipids in the dorsal muscle of Antarctic minke whales are likely to be lower than those of other baleen whales, such as sei (B. borealis) and fin (B. physalus) whales, and this requires further investigation.

著者

Christina Lockyer Claire Garrigue

出版者

Publication Committee for Cetacean Population Studies

雑誌

鯨類資源研究 (ISSN:24345571)

巻号頁・発行日

pp.2020F010, (Released:2021-05-12)

参考文献数

23

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Seven Longman’s beaked whales mass stranded in New Caledonia in November 2013, of which 4 ultimately died, in a first worldwide event reported for this poorly known Ziphioid species. Teeth were extracted, collected and thoroughly cleaned of gum tissue from 3 females ranging from juvenile to adult and one adult male. These were sectioned (crown-root) and prepared using two different methods and examined under microscope magnification when Growth Layer Groups (GLGs) in both dentine and cement were successfully identified. The methods employed for aging included 1) sectioning centrally at approx. 150 µm through crown and root on an Isomet circular diamond saw and examining under a microscope using both transmitted polarised light and plain light; and, 2) thick sectioning (wafering) at approx. 2.5 mm and subsequent decalcifiation in RDO™ (a proprietory brand, Illinois, USA) and then thin sectioning the wafer at 10–25 µm and staining with Ehrlich’s acid haematoxylin. GLGs were investigated in both dentine (25 micron) and cementum (10–15 µm). Layering was evident in both tissues but higher counts were more evident in thin stained sections of cementum. Although dentinal GLGs in untreated tooth sections have been used successfully for aging in Ziphioid species Hyperoodon ampullatus (Christensen 1973, Feyrer et al., 2020), it is believed this is the first time that teeth have been used for estimating age from GLGs in this tropical species.