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Identification of stomach contents from a Shepherd's beaked whale Tasmacetus shepherdi stranded on Tristan da Cunha, South Atlantic

Published online by Cambridge University Press:  21 November 2012

P.B. Best*
Affiliation:
Mammal Research Institute, University of Pretoria, c/o Iziko South African Museum, PO Box 61, Cape Town, 8000, South Africa
M.J. Smale
Affiliation:
Port Elizabeth Museum at Bayworld, Bayworld Centre for Research and Education, PO Box 13147, Humewood, 6013 South Africa, and Department of Zoology, Nelson Mandela Metropolitan University, PO Box 77000, Port Elizabeth, 6031, South Africa
J. Glass
Affiliation:
Director of Fisheries, Fisheries Department, Tristan da Cunha Government, South Atlantic Ocean
K. Herian
Affiliation:
Royal Society for the Protection of Birds Project Officer, Conservation Department, Tristan da Cunha, South Atlantic Ocean
S. Von Der Heyden
Affiliation:
Evolutionary Genomics Group, Department of Botany and Zoology, Stellenbosch University, Private Bag X1, Matieland, 7602South Africa
*
Correspondence should be addressed to: P.B. Best, Mammal Research Institute, University of Pretoria, c/o Iziko South African Museum, PO Box 61, Cape Town, 8000, South Africa email: pbest@iziko.org.za

Abstract

Shepherd's beaked whale Tasmacetus shepherdi is one of the most poorly known cetaceans, whose diet has created some speculation given that its dentition differs greatly from that of most other beaked whales that are primarily teuthophagous. The few stomachs examined previously have given seemingly conflicting dietary information. In this paper the stomach contents of a freshly stranded adult female on Tristan da Cunha have been examined through identification of trace elements and genetic analysis of soft parts. At least 13 cephalopod and 8 fish species were identified from beaks and otoliths respectively, but only undigested fish remains were present in the stomach and identified genetically as Beryx splendens. Reconstituted masses totaled 8809 g for cephalopods and 17,554 g for fish, with four species (Histioteuthis atlantica, Taningia danae, Ommastrephes bartrami and Pholidoteuthis ‘A’) comprising 78.6% of the cephalopods and one species (B. splendens) comprising 87.4% of the fish eaten. It is concluded that Tasmacetus may alternately exploit fish and cephalopods, depending on the time of day and access to seamount or continental slope areas.

Type
Research Article
Copyright
Copyright © Marine Biological Association of the United Kingdom 2012 

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