BRYDES WHALE SAMPLING AT PRINGLE BAY

September 25, 2010 by dyertrust

Monday morning the 12th of July, turned out to be like all other days here at DICT full of great surprises and excitement. We received a phone call from Penelope Aplon, Environmental Manager of the Overstrand Municipality, about a dead washed up whale at Pringle Bay beach.Wilfred Chivelland I grabbed our rubber boots, stranding kit and oil-skins and within 10 minutes we were on the road heading to Pringle Bay.

It is always exciting when whales are found stranded. Of course we would rather see them alive in the ocean, but when they do die and wash ashore there is so much information for us as scientists to obtain. Skin samples can be used for DNA-analysis, which can tell us the sex of the individual as well as the relationship to other animals in our databases. The baleen as well as blubber can be analyzed for isotopes and fatty acid composition, which enables us to trace back the composition of the animals diet, since species specific isotopes are found in different fish species as well as krill. If it is a toothed whale, we can use the teeth to estimate the age of the animal, by counting the layers of dentine in a cross section.

If the animal is fresh, we can obtain a lot more information and conduct a necropsy, where we can take stomach samples and investigate if the animal had any parasites in the lungs or intestines etc, and any scars on the skin will indicate if the animal has been entangled in fishing gear or hit by ship propellers. These samples can help us to better understand the live animals and thereby help us to protect them.

The beach of Pringle Bay was very rocky and unfortunately quite full of rubbish, which told us that there must had been some huge waves coming in over the last days. The whale carcass was laying squeezed inbetween some rocks and it had been dead for at least a week. It was a 9 m juvenileBrydes whale(Balaenoptera brydei). It was very liquified and had obviously been floating at sea for a some time.

A very interesting thing was the cleary defined postmortumsharkbites on the whales blubber. It was clear that the it was sharks and not killer whales, because killer whales would rip the flesh and most likely have eaten the tounge as well. The shark bites were confined at the edge and did not to through to the flesh.

We decided not to indulge ourselves in a major dissection, due to the condition of the animal. We took a big sample of the blubber and the baleensas well as measurements of the fluke and lots of pictures. Blubber has been divided in two pieces and frozen. The samples will be handed over to Mammal Research Insitute (University of Pretoria) and the government department, Oceans and Coasts. It is seldom possible to ascertain the cause of death and this instance was no different.

The carcass will be removed by the municipality, so as not to pose a problem to the public, however leaving a carcass like that can be a rich source of nutrients for other animals.

Katja Vinding Petersen (M.Sc)