2005 - Whitby Naturalists

corals. They are also important ecologically in providing the only fooii
source {br certain other invertebrates such as thc nudibranch moilusc
Tritrmiahombergi. These will disappear as wcll lt Alcyanirun is lost from
the North Sea.
The ttrirri repoft was from Eric Addison, who sighted a common scal
in *re Upper Htrrbour on the 19*,of October.
Fishermen and m:rrine scientists frequently seeil1 io be in dispute as to
hurnan impact on the North Sea. For example, a recent DEFRA, report
clairns that fish popuiations arc being adversely affected by overfishing,
while fishermen dcny this, claiming that mrnttrcrs of some species, sr.tci-t
as haddock, are at ir thirry-year high. The scienri{ic cvidence does secm
to show that year by year stocks of fish are being forced further and
further nofth as the North Sea has experienced arl averagcl
remperaturc risc of one degree C over the last twenty-five years. As the
cooler water specics move out, specics prefcrring warmer water, like
Red Mu1let, are moving in. Researchers at tl"ic Lowestoft Aquacuiture
Laboratories and the University of East Anglia found that twenty-cncr
species had changed distribution in line with the increase of sca
renlperature; eighreen of these had moved very much {urt}ier north:
the cod and hacldock popuiations had moved over one hundred
kilomerrcs north. These workers are exffemely concerned that some
fish popuiations, already overexploited, wiil be put at risk as thcsc
effects kick in more strongly rvith changes in overall climatic pattcrns.
If thc alterations in rhe flow of thc Gtrlf Stream, already beginning,
st:lrt to accelerate, then the ecosystem may enter mto :l process (]f
interaction with meteorologv and hvdrology amounting to positive
ibe.iback. The hundred-kilornertrc shift of these two species sLiggcst
that rnanagement programmes will nccd to be very resfi:ictive if the
dirninlshed southerly populations are to iecover to a reasonable levcl.
As rhcy shift north many species also seek out deeper water, perhaps
searching for c,:oler conditic-rns. Six species including cuckoo ray and
pXaice travc stayed in their original latitudes, but have moved deeper.
5l