Monday, 6 June 2011

Namibian Humpback Whales

06 June 2011 - by Simon Elwen

Humpback whales are one of the most well studied large whales in the world and yet there is still  great uncertainty about many aspects of their lives. Even such relatively simple facts such as where exactly they feed and breed can be surprisingly complicated as individuals sometimes mix between these grounds. The International Whaling Commission (the body which governs and controls global whaling) has defined the  stock of humpback whales which breed off the West coast of Africa as 'Breeding Stock B'. This stock is split in a northern (B1) and southern (B2) component based mainly on historic whaling data records.

Most of the work on this population has taken place in Gabon (by the Wildlife Conservation Society), which is a breeding area and in South Africa (by the University of Pretoria), which is largely seen as a migratory corridor, and there is very little information from the thousands of km of coast in between. Genetic analysis of whales from South Africa and Gabon, has shown some evidence of stock separation, supporting the B1/B2 split. However individual animals have been resighted (from photographs and using genetic sampling) in both South Africa and Gabon showing that at least some animals use both areas. However there is still some confusion about how all these stocks, breeding areas and migratory corridors actually fit together.  Data from the areas in between SA and Gabon are particularly valuable right now in trying to help the IWC answer these questions.

In addition to our main dolphin focus, the NDP has been collecting photographs and genetic samples from humpback whales at sea and from strandings as much as possible since we started. We've also been collating photographs and records from tour boat operators in Walvis Bay which has greatly increased our data set of humpback whale photos. Most of these photos have been taken by Mike Lloyd and Orlanda Sardinha who work on the Cataraman Charters vessels (http://www.namibiancharters.com).  Recently, a colleague of mine who did his PhD work on the humpback whales off western South Africa, matched the photographs we've collected in Namibia to his catalogue of known animals from SA. Unfortunately no matches have been found yet between Namibia and South Africa, but we'll keep looking. Although this is a very small sample (only 35 individuals were identified from tail flukes in Namibia), it is still an interesting result and is being presented as paper SC-63-SH21 at the meeting of the Scientific Committee of the International Whaling Commission which is being held right now in Tromso, Norway (www.iwcoffice.org).


Next up is matching our Namibian whales to the catalogue from Gabon. Meanwhile, work continues here in Walvis Bay and we hope to see lots more humpback whales this winter!

                           

1 comment:

Michelle Anne Custodio said...

Super excited to see its kind. We'll be seeing dolphins oban. It'll sure be fun.