- Cod and other coldwater fish in the North Sea and North
Atlantic could soon be replaced by subtropical marine species such as tuna,
sharks and sea horses lured by warmer waters caused by climate change.
-
- One of Britain's leading marine scientists has warned
that a minor change in temperature of the seas off the north-west coast
of Scotland and the rest of the UK is having a dramatic effect on traditional
marine life.
-
- The once-thriving cod stocks, depleted by over-fishing,
are being replaced by tuna, red mullet, horse mackerel, pilchard, squid,
john dory, sea horses and leatherback turtles.
-
- Martin Angel, a government adviser and chairman of a
steering group investigating marine productivity, said close examination
of the tiny zooplankton species Calanus finmarchicus, which provides a
vital food source for young cod, salmon and other coldwater species, shows
it is being driven further north as the seas around Britain warm.
-
- "Calanus finmarchicus used to be extremely abundant
in the North Sea," Dr Angel said. "If you dipped a plankton net
into the waters off Britain it would make up about 80 per cent of what
was caught. But as the seas warm, the whole ecological system is changing;
plankton more usually associated with southern waters takes over and the
species of fish which feed on it expand their traditional territories."
-
- Dr Angel said the largest change has been in the past
15 years, and that within 10 years tuna could be almost as common in Scottish
waters as cod. "These subtropical species have been migrating north
at a rate of 50 kilometres a year," said the scientist who wrote the
last Oslo and Paris Convention report into the health of the Atlantic and
North Sea and who was the UK chairman of the International Year of the
Ocean.
-
- "The instance of leatherback turtles finding their
way to Britain has increased in the last few years because they feed on
jellyfish which thrive in the warmer water. Since the mid-1980s, there
has also been a rise in the amount of tuna caught in Scottish waters, especially
the smaller skipjack variety. This kind of change is happening with just
a minimal warming of sea temperature but it is producing quite enormous
environmental changes."
-
- Dr Angel, who is based at the Southampton Oceanography
Centre, said that within the next few years sea horses will be a common
sight around the Scottish coast as will several species of sharks and john
dory, an olive-green spiny fish more usually associated with continental
shelf waters from south-east Queensland, south and north-west Western Australia,
the western Indian Ocean, eastern Atlantic, Mediterranean and the waters
of New Zealand, Japan and Spain.
-
- "The rate by which john dory-like fish are advancing
up the coast is incredible," said Dr Angel. "Already they can
be found off Wales and within a few years they will undoubtedly be in Scotland."
The UK crab and lobster fisheries are thriving as the crustaceans enjoy
the warmer waters and other fish species traditionally more popular in
Spain and France are being caught in the North Sea.
-
- "A squid fishery is developing off the coast of
Aberdeen," a spokeswoman for WWF Scotland said. "There have been
reports of squid in Scottish waters for years but now it's actually reaching
big enough proportions for fishermen to make money from it. It's not just
the temperature of the sea; the chemical balance of the water is also changing
and having an effect on the ecological system which is attracting different
fish."
-
- The influx of new species is not necessarily good news
for the beleaguered fishing industry. Dr Angel said: "It's not just
about replacing one species with another as these new species are not as
productive as cod. Even if the fishermen could fish as much as they wanted
they would never catch as much; there are just not the numbers to sustain
that."
-
- © 2004 Independent Digital (UK) Ltd http://news.independent.co.uk/uk/environment/story.jsp?story=513250
|