Details are limited to information relevant to
the UK marine habitats and species listed in the
Habitats Directive and the Birds Directive.
[pr] indicates that the paper is from a peer reviewed
journal or report
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Natura 2000 Habitats &
Species
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Fishing Technique
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Effects
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Locations
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Reference
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REF: 66
Shallow inlets and bays
Sandbanks
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Beam trawling
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Experimental beam trawling trials to investigate
effects on megafauna immediately after fishing
and 6 months later on two seabed types - mobile
megaripple structures and stable uniform sediment.
Control and fished areas were sampled.
Short term changes (within ca. 24hrs) were
recorded in the megafaunal community in stable
sediments but not in the mobile sediments.
There were decreases in the relatively slow
moving megafauna eg Aphrodita aculeata,
Macropodia deflexa and Asterias
rubens. Some mobile species (eg. Pagurus
bernhardus and Ophiura ophiura
increased in the trawled area and are known
to migrate into areas of fishing disturbance.
There were also increases in some relatively
sessile species eg. Mya truncata
in the trawled areas but not statistically
significant. The effects on the megafaunal
community were not uniform, even though the
fished areas were completely swept by the
gear at least once. Six months later, seasonal
changes had occurred in both communities and
the effects of the trawling disturbance were
no longer evident.
No significant change in biomass of hydroids
and Alcyonium digitatum recorded
immediately after fishing although these organisms
were the largest proportion of the biomass
of beam trawl catches at the study site. Repeated
and more intense trawling effort is likely
to have a greater effect on these organisms.
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Area off north east coast of Anglesey, Liverpool
Bay.
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Kaiser et al., (1998) Changes in megafaunal
benthic communities in different habitats
after trawling disturbance. ICES J.Mar.Sci.
55:353-361.
[PR]
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REF: 67
Shallow inlets and bays
Sandbanks
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Bottom trawling
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Author develops a conceptual model of gear
impacts across gradients of habitat complexity
and levels of fishing effort. Habitats are
grouped into 8 general categories and scored
according to their complexity. The conceptual
model shows the response of the range of seafloor
habitat types to increases in fishing effort
scored from 0 to 4. It shows a range of changes
in habitat complexity based on the effects
of fishing grear and predicts reductions in
the complexity provided by bedforms from direct
smoothing of gear.
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Auster, P.J. (1998) A conceptual model of
the impacts of fishing gear on the integrity
of fish habitats. Cons.Biol. 12(6): 1198-1203.
[PR]
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REF: 68
Shallow inlets and bays
Sandbanks
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Otter trawling
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Comparison of two fishing areas over a three
year period, one of restricted fishing with
light levels of trawling and the other with
high levels of trawling. Results indicate
that intensive trawling significantly decreased
habitat heterogeneity. All the epifaunal invertebrates
counted were less abundant in the heavily
trawled area. No differences were found in
the number of infaunal crustacean species
but there were more polychaete species in
the lightly trawled area every year, implying
that high levels of trawling can reduce biodiversity.
This also suggests that high-intensity trawling
favours opportunistic species.
High numbers of ophiuroids and the amphinomid
polychaete Chloeia pinnata in the highly
trawled area may be because they can pass
through net mesh unscathed and then benefit
from feeding on those organisms that the net
crushes or kills. C.pinnata was also
found to be the most common invertebrate in
the diet of several commercially important
flatfish species in both areas suggesting
that certain prey species and commercially
important fish may be enhanced by some level
of trawling disturbance.
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Monterey Bay, USA
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Engel, J. & Kvitek, R. (1998) Effects
of otter trawling on benthic community in
Monterey Bay National Marine Sanctuary. Cons.Biol.12(6):1204-214.
[PR]
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REF: 69
Shallow inlets and bays
Sandbanks
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Otter trawls
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Three year study into the effects of otter
trawling on a sandy-bottom ecosystem of the
Grand Banks. Sediment samples, acoustic measurements
and video surveys undertaken.
Habitat effects Statistical analysis
of seven size fractions gave no evidence that
trawling had any immediate effect on sediment
grain size. Sidescan sonar showed the persistence
of door tracks was variable from several months
to a year. Acoustic data suggest that repeated
trawling did not affect sediment texture but
increased surface relief or roughness. Small-scale
biogenic sediment structure down to 4.5cm
also changed. Video surveys showed clear differences
in the appearance of the seabed. After trawling
hummocks were removed or less pronounced,
organic floc was either absent or less abundant
and mottled appearance of the seabed less
pronounced. Sediment grain size data suggest
that there may be natural inter-annual changes
that are more pronounced than those caused
by the experimental trawling.
Species effects. Video imagery showed
organisms and shell has organised into linear
features in the trawled areas. At times high
concentrations of Strongylocentrotus pallidus
were visible and seemed to be scavenging on
dead snow crabs. Biological effects have still
to be examined.
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Grand Banks
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Schwinghamer et al., (1998) Effects
of experimental otter trawling on surficial
sediment properties of a sandy-bottom ecosystem
on the Grand Banks of Newfoundland. Cons.Biol
12(6): 1215-1222.
[PR]
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