Blue whale population increasing

The slow but steady comeback of the blue whale - the biggest creature to have lived on Earth that was driven nearly to extinction by commercial whalers - is continuing, the latest whale research cruise has confirmed.

The research was conducted by a four-strong team of cetacean scientists for
the International Whaling Commission (IWC), working from the Japanese research ship Shonan Maru No 2 that arrived back in Cape Town harbour last week after a two-month cruise deep into the Antarctic waters. It was the
latest research cruise in a 28-year study of whale populations in the Southern Ocean, directed by the IWC's scientific committee.

"The research programme is unanimously supported by the 66 member nations of the IWC, including South Africa," said scientific committee member Peter Best, who works at Pretoria University's Mammal Research Institute.

He explained that the research did not involve the killing or capture of any whales and was conducted completely independently of Japan's controversial whaling in Antarctica. The worst experience the whales in this research programme suffer is a tiny pin-prick when the scientists take small biopsy samples of their skin for genetic testing. This used to be done using a
crossbow, but the scientists now use specially adapted rifles, Best explained. "These rifles tend to have a longer range and a flatter trajectory, and enable sampling of the more evasive species such as blue and fin whales."

During the cruise, the team of scientists, led by New Zealander Paul Ensor, counted 63 blue whales, 295 fin whales, 532 humpbacks, 971 minkes, 75 killer whales, 37 sperm whales, 24 southern bottlenose whales, and three southern rights. Skin samples for genetic testing were taken from 36 blue whales, 71 humpbacks, 26 fin whales, and two southern rights. Photos for identifying individual whales included images of 52 blue whales, 105 humpbacks, and the three southern rights.

The results of the study will be presented to the IWC's annual meeting in St Kitts and Nevis in May and June of this year.

Best said it was difficult to draw conclusions from a single survey, but that the large number of blue whales spotted was expected, "given that we now know they are increasing." The large number of fin whales is partly due to a shift in the operating area of the vessel to the north, specifically to try and establish what might be happening to this species. "The low number of right whales is surprising, as is the lack of sei whales, but as these two species are principally copepod-eaters - unlike the other baleen whales - it is possible there is a common cause which I would guess is that the vessel failed to sample the water bodies where these two species normally feed."

The relatively large number of biopsies collected also probably reflected a shift in operating strategy, Best suggested. "There is now a push to learn more about stock identity - through acoustics, genetics and tagging - than before."

source: www.iol.co.za