A couple of rock doves passed over the Arctic Sunrise this morning, heading for nearby cliffs on Fetlar. These birds are typically found on cliffs like those around Shetland, but are probably better known as the feral pigeons that have colonised the artificial cliffs we have built in our towns and cities.
It's easy to dismiss pigeons, but around the world they are very successful at colonising and diversifying. They also represent two of the most famous cases of extinction-by-humans in history. The dodo, of course was a large flightless pigeon. Everyone knows what happened to them. Not everyone knows about passenger pigeons though, which became extinct in 1914. The last wild passenger pigeon was shot 14 years earlier in 1900.
In itself the extinction of a species by mankind may not seem that remarkable - but when you consider that the passenger was the commonest bird in the world, representing some 25-40 per cent of all land birds in the USA, it suddenly becomes more alarming. Passenger pigeons used to travel in enormous flocks, in 1870 one flock was estimated to contain a mind-boggling birds, and was over 510km long. The flocks were so big that they blotted out the sun.
Passenger pigeons were hunted non-stop - for meat and for feathers to fill quilts, and of course it seemed impossible that a population that size could be dented, never mind exterminated. But it was. And even when the numbers had dwindled drastically, the persecution continued.
But why is that relevant to us on the Arctic Sunrise? In many ways it's been the same story with cod. When cod fisheries were first discovered in the north-west Atlantic, they were seen as inexhaustible. Fishermen's tales told of cod so numerous that you could walk on their backs and not get your feet wet. Fishing them was apparently as easy as dropping in a basket, which you would haul out full of fish. It was believed that we could never damage these stocks, let alone destroy them. But we managed to do just that. After decades of exploitation the Atlantic cod fisheries collapsed in the early 1990s and still show no signs of recovery.
Let's hope it's not too late to save the cod on this side of the Atlantic.