First record of false killer whales (Pseudorca crassidens) in the Falkland Islands (Malvinas)

Abstract

The false killer whale (Pseudorca crassidens) is primarily distributed across tropical, subtropical and warm temperate waters, with few records originating above 50° latitude in each hemisphere. In February 2013, a mass stranding of 22 false killer whales occurred on the east coast of the Falkland Islands (Malvinas; 51.83°S, 58.24°W). Of the 20 sexed animals, 11 were male and 9 were female. Total body lengths ranged from 396 to 581 cm, and the stranded animals likely consisted entirely of mature adults. There were no significant differences between the sexes in proportional body measurements, with the exception of proportional dorsal fin height which was significantly higher in males. Tooth counts ranged from 14 to 18 in the upper jaws, and from 14 to 20 in the lower jaws. Four stomachs were investigated, of which three were empty and one contained a single Onychoteuthidae squid (Onykia ingens) beak. Mitochondrial control region sequences from the stranded animals indicated greater genetic connectivity between the south Pacific and south Atlantic than between the south and north Atlantic ocean basins. Given the absence of full necropsies, the underlying reasons for the stranding could not be ascertained. This mass stranding represents the first confirmed record of false killer whales in the Falkland Islands, and provides new information on the species in the southernmost part of its distributional range.