The top predators

NIWA scientist Stu Hanchet explains what types of top predators can be found in the Ross Sea.

Points of interest

• What are the top predators?

• Discuss what would happen if top predators were removed from the food chain ( for example seals or whales).

Transcript

STU HANCHET

So by top predators we mean the large marine mammals, we mean the penguins, the marine birds such as the penguins, the large predatory fish and the seals. So, within the Ross Sea these top predators divide into 2 main categories – one group which are plankton feeding and the other group which are feeding mainly on fish and squid.

Now during this voyage we’ve seen several species which come into both categories. We’ve seen humpback whales, we’ve seen Adelie penguins and we’ve seen crab eater seals which are out on the ice flows. And amongst the fish and squid eaters we’ve seen the leopard seals on the ice flows and we’ve also caught several Antarctic toothfish in the trawl. Now the – most other parts of the world the top predators have been commercially exploited by humans over time, for example the great whales have been decimated and there’s been large amounts of over fishing by the large predatory fish and seals as well in some areas. However in the Ross Sea – apart from the loss of the great whales during the last century – the eco-system is relatively intact. So an important part of this voyage is to try and understand the eco-system better so that we can understand the effect that human activity such as fishing for Antarctic toothfish, the scientific whaling by the Japanese and effects of climate change may have on the eco-system.