[MARMAM] New article on stable isotopes in the baleen of minke whale

Yoko Mitani mitaniyoko at yahoo.co.jp
Mon Apr 24 19:36:36 PDT 2006

Dear All,

The following paper is now available.

PDF reprints are available upon request (contact email:
ymitani at bio.titech.ac.jp

"Patterns of stable carbon and nitrogen isotopes in the baleen of  
common minke whale (Balaenoptera acutorostrata) from the western  
North Pacific."

Yoko Mitani, Takeharu Bando, Noriyuki Takai, Wataru Sakamoto.
Fisheries Science72 (1): 69-76 (2006)

Stable carbon and nitrogen isotope ratios were determined in the  
baleen plates of 17 common minke whales (Balaenoptera acutorostrata)  
from the northwestern Pacific Ocean off Japan as well as prey species  
(krill [Euphasusia pacifica], Japanese anchovy [Engraulis japonicus]  
and Pacific saury [Cololabis saira]) collected in the stomach  
contents to investigate the trophic relationship between the minke  
whales and their prey.  A few d15N-depleted peaks occurred along the  
length of baleen plates for 10 males irrespective of stomach contents  
(anchovies and sauries).  Similar d15N-depleted peaks were also found  
for one female and two immatures.  It was likely that these d15N- 
depleted peaks formed in early summer.  The d15N values in Pacific  
saury (9.3±1.4‰) did not differ significantly from that in Japanese  
anchovy (8.8±0.9‰). In contrast, d15N in krill (7.2±0.5‰ in July  
and 8.0±0.2‰ in September) was significantly lower than in Pacific  
saury.  Thus, we expect that these peaks might reflect the dietary  
change from krill to fishes in the feeding migration of the whales.   
Growth rate of the baleen plate was estimated to be 129 mm y-1, and  
it appeared that dietary record of about 1.4 years remained in the  
baleen plate.  For two immature whales, the maximum value of d15N  
occurred at the tip of baleen.  This d15N enrichment may possibly be  
useful for discriminating weanlings and older whales.

Key Words: common minke whales, stable isotopes, baleen, feeding  
ecology, North Pacific

Yoko Mitani
Faculty of Bioscience and Biotechnology, Tokyo Institute of Technology,
2-12-1 W3-43 Ookayama, Meguro, Tokyo, 152-8551, JAPAN
Tel: +81-3-5734-3383
Fax: +81-3-5734-2946
E-mail: ymitani at bio.titech.ac.jp

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