Monday, August 16, 2010
I GOT a phone call from an excited friend of mine the other day.
He was on holidays and had been sea angling with his son in Ballinskelligs Bay in west Kerry. They had just caught two gilthead bream.
My friend has a keen interest in nature and has been fishing in these waters all his life but had never seen gilthead bream before. He had to use the internet to identify them when he got ashore. This is not surprising because they are a warm water species from off Spain and Portugal.
One of the most conclusive proofs that global warming is actually happening is that the temperature of the seas around our coasts, both in summer and in winter, is rising slowly but steadily (see Donal Hickey’s column, left). This means species, such as the gilthead bream, and other even more exotic fish such as Atlantic trigger fish and even flying fish are turning up with increasing frequency. Of course, the down-side of this is that many cold water species, including commercially important ones such as cod, are abandoning our shores and heading north in search of cooler water.
The gilthead bream is also commercially important in its home waters. It’s a large sea bream which gets its name from a gold-coloured band behind its head. It is what marine biologists call 'dorso-ventrally flattened', meaning it's not flat from side to side, like a plaice, but up and down like all the breams. It can grow to be 50 centimetres long and weigh 15 kilos, but fish of this size are rare nowadays because they taste good and have been over-fished.
Nowadays most larger giltheads are reared in fish farms and appear on continental menus as 'dorada' in Spanish, 'daurade' in French or 'orata' in Italian.
The effect human activity is having on marine life all over the globe is very depressing. There are the direct effects, such as over-fishing, and the indirect effects, such as global warming, and it adds up to a very long list.
What is even more depressing is that it seems likely many species of fish and other forms of marine life will become extinct before they’re even discovered by science.
This was highlighted recently by the publication of the results of a massive 10-year study of life in all the seas and oceans of the world. It involved 538 field expeditions by marine biologists from many nations, cost about €450 million and generated over 2,600 scientific papers. It discovered at least 1,200 previously unknown species of marine life but this is only a fraction of what's still out there.
The figures are quite extraordinary. The best estimate is that the number of marine species now known runs at about 230,000 and that this represents between 20% and 30% of the likely total. Of course, fish species are quite a small fraction of the total of things that live in the sea. Earlier this year it was estimated that there were 16,764 known species of sea fish. Scientists reckon around 5,000 species still await discovery, which is about double the number of new ones described in the past 20 years. But over that period some known fish stocks have declined by up to 90% as a result of human activity, so it seems almost inevitable that many species will become extinct before we even meet them.
Gilthead bream may have been a startling catch for a sea angler in Ballinskelligs Bay but there are probably a lot more startling events in store for us as we relentlessly meddle with the ecological balance of the oceans.
* dick.warner@examiner.ie
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