Anonim

Whaling; the sea lions disappear
The massacre of cetaceans by Russians and Japanese has had unexpected consequences.

An image of whaling in the post-war period, the years of the great massacre by the whaling fleets of Japan and Russia.
An image of whaling in the post-war period, the years of the great massacre by the whaling fleets of Japan and Russia.

It was thought that whaling had only hit the large cetaceans. A study published in the American journal Proceedings of the national academy of science instead shows that the effects were much wider, and that they still last. Whales, almost all species, were in fact prey to the herds of killer whales that populated (and populate) the waters of all the oceans. Killer whales, the largest ocean hunters, have turned to other animals after a significant part of their prey. In this case, despite the much lower caloric power, the large predatory dolphins have thus begun to hunt and capture the sea lions and seals that populate the arctic seas.
To prove their hypothesis, researchers, US marine biologists, have graphed the number of whales captured by the Russian and Japanese whaling ships and the decrease in sea lions and seals. As the number of whales reaches the lowest value, the populations of the pinnipeds of the Arctic seas also begin to decline.
But it's not over. Given that, thanks also to the help of man, both seals and seals have diminished too much, orcas must begin to eat sea otters, small and very poor prey from the nutritional point of view. And, even in this case, the sea otter population of the Arctic seas decreases dramatically. The consequences of this decrease are curious and devastating. The sea otters in fact feed on sea urchins, which in turn graze on the bottom of the seas with meals based on giant algae. Less otters means more hedgehogs, and if the number of hedgehogs increases it can only decrease that of marine algae, thus upsetting a very important coastal ecosystem, in which many species of fish essential for fishing find refuge.
Here, say the authors of the article, how the killing of thousands of whales has upset ecosystems throughout the northern Pacific. And they add that in the Antarctic seas the massacre was even greater and prolonged. What will be the effects on the oceans around the South Pole?

(News updated September 29, 2003)