Hello,
My name is Joachim Maes and I am working since 1995 as a fish biologist in
the Schelde estuary (Belgium+ Netherlands).
Recent figures of the shrimp fisheries in this area indicate a dramatical
decrease of the total yearly catch. Between 1993 and 1996 the average yearly
shrimp catch of one beam trawl was situated between 5000 kg and 10000 kg. In
1998 only 400 kg on average could be caught by one beam trawl.
Most likely, heavy dredging activies could be held responsable for this
dramatical decrease. These dredging activities are necessary to maintain
shipping and navigation to the port of Antwerp.
In my view, dredging has two possible effects on shrimps and fish.
(1) Fish and crustaceans are impinged by the pumps of dredging boats and die.
(2) Fish and crustaceans try to avoid dump sites located ouside the main
shipping channel.We have observed that all fish and crustaceans trapped in
fyke nets were killed when polluted silt was dumped at a location nearby.
After dumping, neither fish nor crustaceans were caught for at least three days.
I have, however, no relevant information on the first effect. Is there any
literature known on the intake numbers of organisms by dredging ships or has
anybody experience in this field.
All information is welcome
Friendly greetings
Joachim Maes
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