Orca in the tropics ....!
17 August 2010 - 3:45pm
The global status of orca was assessed by the IWC during its 59th Annual Meeting held in Anchorage, Alaska, during 2007 and concluded that ‘very little information on any aspect of killer whale biology in many areas hinders any assessment of their status’ thus prompting some of the research currently under way today.
Although known to inhabit all the world's oceans, documented sightings of orca are more lacking in some parts of the world than others. This is particularly the case in tropical waters and one area where little is known is in the Western Atlantic Ocean and Caribbean Sea, although this gap is slowly being filled and more information is coming to light with a collaborative approach encouraged amongst researchers and other stakeholders in the region.
Colleagues and friends of WDCS have recently published a paper on "Killer whale occurrence in Venezuelan waters, 1982 - 2008" in the Latin American Journal of Aquatic Mammals (LAJAM). The study collected eighteen sighting records covering the time period April 1982 - January 2008 and brought to light one interesting incident (which was videotaped) involving an attack by two killer whales on a leatherback turtle. The encounter ended when the adult female (the other animal being a sub-adult) of the pair took the turtle in its mouth and dove to a depth of greater than 100m; it is not known what became of the turtle! During the entire encounter, an adult male was seen in the distance - possibly keeping an eye on the proceedings? Some of the sightings noted the apparent co-occurrence of killer whales with cold water incursions that would coincide with the presence of known prey species, such as tunas and billfish; as has been suggested for other areas of the Atlantic Ocean. The authors however, noted that there is currently not enough information to speculate on any seasonality to the occurrence of the killer whale in Venezuelan waters although it has been hypothesised that in Brazil, killer whales could use shallow, coastal habitats in the State of Rio de Janeiro as feeding grounds on a seasonal basis, consistent with the results of the study of interactions of killer whales with the longline fishing fleet off Brazil, which reported that interactions occurred primarily from June to February.
Driven by Angiolina Henriquez, from the Aruba Marine Mammal Foundation, and Jaime Bolanos from SEAVIDA, Venezuela, there is currently a collaborative effort underway to collect information on orca sightings in the Caribbean Sea. To date they can count on information of sightings from Aruba, Barbados, Curacao, Puerto Rico and a new one for Venezuela from three months ago but are hoping for many more in the months to come. If you or anyone you know might be able to help with adding more sightings to the database then they would be very pleased to hear from you. For a database form with the information that they are collecting and/or a PDF copy of the above quoted note in LAJAM you can contact Jaime Bolanos at firstname.lastname@example.org