The union in deep waters between the world's largest animal and another species which is considerably smaller, although still huge, bore strange fruit.
A unique female hybrid with a mixture of blue and fin whale characteristics was produced - only to be harpooned by an Icelandic whaler.
Sir Crispin Tickell, the former UK ambassador to the United Nations, told the story while launching a fat UN report on the worsening state of the global environment in London.
Perhaps the blue whale, now among the rarest of living things, can no longer find its own kind and has had to broaden its horizons. After all, there is an awful lot of ocean and only a few hundred blues left.
The greatest of the great whales - males can top 100 feet and 150 tonnes - was the most ruthlessly hunted and the slaughter continued in secret even after it was given protected status. It emerged this year that Russia had continued to harpoon thousands of them into the 1960s.
The fin whale is the second largest animal in the family headed by the blue, the 'baleen' whales, so-called because of their baleen plates - filters of bone which they use to trap plankton and other food.
Ray Gambell, secretary of the International Whaling Commission, confirmed Sir Crispin's strange story. In 1986 an Icelandic whaler had killed a hybrid whale. Several years later, Icelandic scientists produced a report announcing that the victim was indeed a blue-fin cross. Moreover, she was pregnant with a healthy foetus.
However, hardly anyone noticed their paper in a little- known scientific journal.
'But I'm afraid there's really no reason to believe it was loneliness which caused a blue to mate with a fin,' Dr Gambell said yesterday. For the hybrid had been able to find a blue male to mate with. The scientists established this after examining the genetic make-up of her foetus.
'Well, it's a nice story,' said Sir Crispin, warden of Green College, Oxford, who is also chairman of a recently- appointed panel to advise John Major on environmental issues. 'I was told it over dinner by a biologist and I couldn't resist repeating it.'
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