Greenland sharks (Somniosus microcephalus) scavenge offal from minke (Balaenoptera acutorostrata) whaling operations in Svalbard (Norway)

Abstract

Minke whale (Balaenoptera acutorostrata) tissue (mainly blubber) was found in the gastrointestinal tracks of Greenland sharks (Somniosus microcephalus) collected in Kongsfjorden, Svalbard, Norway. In order to determine whether the sharks were actively hunting the whales, finding naturally dead whales or consuming offal from whaling, we checked the genetic identity of the whale tissue found in the sharks against the DNA register for minke whales taken in Norwegian whaling operations. All of the minke whale samples from the sharks that had DNA of sufficient quality to perform individual identifications were traceable to the whaling DNA register. During whaling operations, the blubber is stripped from the carcass and thrown overboard. The blubber strips float on the surface and are available for surface-feeding predators. This study revealed that Greenland sharks are scavenging this material; additionally, it demonstrates the capacity of this ‘benthic-feeding’ shark to utilize the whole water column for foraging.

Keywords: Carrion; diet; DNA register; Greenland shark; minke whale

(Published: 30 June 2011)

Citation: Polar Research 2011, 30, 7342, DOI: 10.3402/polar.v30i0.7342