Gonatus fabricii (Mollusca, Theuthida) as an important food source for sperm whales (Physeter macrocephalus) in the Northeast Atlantic

An analysis of cephalopod beaks from the stomachs of 10 sperm whales stranded in Denmark during 1991, 1997 and 2000 revealed Gonatus fabricii as the dominant prey species (>98% of 2536 identified lower beaks). Other species found were: Todarodes sagittatus, Histioteuthis sp., Cyclioteuthis sp., Haliphron atlanticus, and Bathypolypus sp. The majority (73.5%, n = 2522) of the Gonatus fabricii lower beaks were from individuals with an estimated mantle length between 192 and 257 mm, corresponding with the length of mature ontogenetically transformed immobilized females. The results may therefore further support sperm whale predation in the North Atlantic upon an immobile squid stage.