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The populations of cormorants have been increasing
very rapidly since 1970, particularly in fresh
water. In the United Kingdom, fishermen, the
Ministry and British naturalists are very worried
about the presence of these birds.
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It is estimated that at the moment the European
population of cormorants numbers between 250
000 and 300 000 couples. Approximately 7500
pairs nest in the United Kingdom and 1500 of
these on fresh water. During the Winter, half
of the 25 000 to 30 000 are on inland waters.
In the British Isles there are two sorts of
cormorant: the large cormorant (Carbo carbo
sinensis) which nests in trees and comes from
Northern Europe in Winter and the small cormorant
(Carbo carbo) which nests on the ground and
lives near the sea.
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| Since the Middle
Ages populations have been controlled by withdrawing
eggs but from 1960 onwards the populations have
been increasing. Since 1981, in the United Kingdom
as in all of Europe the cormorant has been protected
by a Bird Protection Directive (1979). They
cannot be eliminated either in the nest or have
their eggs destroyed. When they cause serious
problems for the fishing industry and for other
wild species shooting permits can be issued.
The
cormorant eats exclusively a diet of fish
and mainly live fish. Its prey measures 5
to 15 cms but is sometimes much bigger. The
damage to fish farming is serious as cormorants
injure many fish which they do not actually
consume and these fish cannot be sold. They
have a severe impact on the ecological and
economic situation for ponds and reservoirs
even if the consequences are difficult to
estimate precisely.
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Cormorants make no distinction between the species
they eat and consume both common and protected
fish, and in particular, migratory species such
as salmon, sea trout and eels. These species
already suffer from a deterioration in the quality
of water and their environment and the presence
of these birds makes the situation even worse
and endangers their preservation.
The harm and strain inflicted by the birds is
more or less manageable depending on the areas
of water concerned and the existing fish populations.
Each case is particular and it is impossible
to define an acceptable level of presence. The
impact of cormorants on the fish can be diminished
in different ways either directly or indirectly.
The environment could be improved and zones
created which would be impenetrable to cormorants.
The measures would have less impact in the areas
most favourable to fish.
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Is shooting helpful ? The English are very doubtful
about the results ! After a shooting session
the birds leave but only to come back a few
days later. The birds which have been killed
are replaced by others which take advantage
of the situation. Shooting and scaring do not
seem to have an effect on the population present
in any one place. To achieve a real reduction
in the number of birds present in Europe it
would be necessary to shoot 50 000 to 60 000
cormorants ! Is this really possible ? Is it
reasonable? Wouldn't it be better to confine
cormorants to less sensitive areas (lakes, rivers)
rather than shooting them or frightening them
away to other sensitive sites? Moreover shooting
is hardly practicable in some places such as
towns.
A local approach to the problem would seem more
efficient than random shooting. The best solution
would most likely be to tackle the issue, as
in the past, at its source, which means at the
nesting sites. To reduce reproduction by limiting
the number of birds nesting seems obvious !
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thanks to Sea-River 75,
boulevard Haussman 75008 PARIS
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