Killer whale (Orcinus orca) occurrence in Venezuelan waters, 1982-2008

Abstract

Records for the killer whale (Orcinus orca) off Venezuela are scarce. The revision of the status of killer whales was set as a high priority by the IWC during its 58th Annual Meeting held in St. Kitts and Nevis during 2005. Here we present a review of recent occurrences of killer whales in Venezuelan waters. In the absence of dedicated survey effort, a request for information was sent during 2006 to an environmental discussion list and colleagues working on marine mammals in Venezuela. Twelve records were collected for February 2001 to January 2008. Four records were accompanied by still photographs or video. Noteworthy is a videotaped attack by two killer whales on a leatherback turtle (Dermochelys coriacea) off northeastern Venezuela on 15 April 2007. Records not accompanied by photo-documentation were accepted if: 1) confirmed by a marine biologist aboard, or 2) provided by an observer who demonstrated familiarity with diagnostic characteristics of the species. Sightings were recorded off central and northeastern Venezuela (n=9 and 3, respectively). At least an adult male has notches in its dorsal fin that could be used for photo-identificacion. Bottom depth was 10-1500 m (mean=519 +/- SD= 470; n=12). Group size ranged from 1-5 animals (mean =3 +/- SD= 1.76; n=12). Adult males were present in 92% of reported sightings. Juveniles were present in 17% of reported sightins. Four sightings recorded in the same general area during two consecutive days of two consecutive weekends could be of the same pod.This pod was reported to be comprised of three adult males and two females. Interestingly, most records are from December through May. There is currently not enough information to speculate on any seasonality to the occurrence of this species in Venezuelan waters. Dedicated research effort is strongly recommended to evaluate the presence of killer whales and other cetacean species in offshore areas.