Here is a quote from the
Cormorants.info web site.
Quote:
Why not just shoot cormorants?
Shooting cormorants as an aid to scaring can work, but its effectiveness varies. At some sites, shooting, to kill or to scare, appears to make little difference to the number of cormorants present at the site. At others, birds leave for a short while, but return after several weeks.
The cormorants in the UK are part of the European population. Any large-scale cull of cormorants here may simply create a 'gap' for birds from elsewhere in Europe. To make any difference to the cormorant population, it is estimated that 30,000-60,000 cormorants would have to be killed every year throughout Europe. This is not only impractical; it simply would not be acceptable to the general public.
There is a lot of good information on this site as well as others. Have a read.
Cheers,
Mike