Biology Reference
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Fig. 6.15 Distribution of
cod and haddock expressed
in acoustic density
(m 2
a
nm 2 ) before ( a ),
during ( b ), and after ( c )
seismic shooting. The
region represented has a
diameter of 40 nautical
miles (Reproduced with
permission from Engas
et al. 1996 )
b
c
ACOUSTIC DENSITY
ABOVE
320
320
254
202
150
127
254 -
202 -
150 -
127 -
101 -
80 -
101
64 -
80
50 -
64
40 -
50
40
32 -
25 -
32
25
20
16
13
10
20 -
16 -
13 -
10 -
BELOW
In these systems, evidence has confirmed that oil and gas prospecting by
using air-guns has severe consequences on the local abundance of pelagic fishes of
strategic importance for the fishery such as cod ( Gadus morhua ) and haddock
( Melanogrammas aeglefinus ). In fact, after acoustic mapping and fishing trials with
trawl and longlines in the central Barents Sea, Engas et al. ( 1996 ) have found that
seismic shooting severely reduced distribution, local abundance, and catch rate in an
area of 40
40 nautical miles. Close to the shooting area the reduction of catches
was 70 % for trawls and 45 % for longline technique (Fig. 6.15 ).
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