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: 76
Shallow inlets and bays
Sandbanks
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Bottom trawling and dredging.
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Review paper. Authors suggest that effects
of bottom trawling are the marine equivalent
of forest clearcutting, acting as a major
threat to biological diversity and economic
sustainability, and occurring at a rate two
orders of magnitude higher than forest loss
worldwide. Reasons include reduction in structural
complexity of benthic communities, alternation
of biogeochemical cycles, and slow recovery
after disturbance. The effects can be large
and long-lasting on benthic communities as
well as young stages of some commercially
important fishes although other species benefit
when structural complexity is reduced. Recent
experimental studies on trawling and dredging
impacts on benthic communities are tabulated.
The paper describes the extent and severity
of the activity noting that advances in fishing
technology have virtually eliminated de facto
refuges from trawling, and that frequency
of trawling is orders of magnitude higher
than other severe seabed disturbances. It
calls for the establishment of refuges free
of mobile fishing gear, modification of fishing
methods and a precautionary approach to management.
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Watling, L. & Norse, E.A. (1998) Disturbance
of the seabed by mobile fishing gear: a comparison
to forest clearcutting. Cons.Biol. 12(6):1180-1197.
[PR]
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REF: 77
Shallow inlets and bays
Estuaries
Mudflats and sandflats
Reefs
Sandbanks
Seabirds
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Various
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Review paper describing direct and indirect
effects of fishing gears on benthic fauna
and habitat, fish community structure and
trophic interactions.
Effects on habitats and benthic communities
most readily identified and last longest in
those areas that experience infrequent natural
disturbance. Initial effects can be dramatic,
additional effects more difficult to detect.
Authors concluded that once an ecosystem enters
the fished state, diversity, structure and
fish production tend to remain relatively
stable across a wide range of fishing intensities.
Fishing has accelerated and magnified natural
declines in abundance of many forage fishes
and this has led to reduced reproductive success
and abundance in birds and marine mammals.
Dramatic and apparently compensatory shifts
in the biomass of different species in many
fished ecosystems are considered to often
be driven by environmental change rather than
indirect effects of fishing. When predator
or prey fill a key role, fishing can have
dramatic indirect effects on community structure
Authors conclude that many marine ecosystems
are overfished and that better management
is needed. Population-based management, management
which minimises the direct and indirect effects
of fishing and the case for marine reserves
as an adjunct to other management methods
are discussed.
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Jennings, S. & Kaiser, M.J. (1998) The
effects of fishing on marine ecosystems. Adv.Mar.Biol.
34:201-352.
[PR]
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REF: 78
Shallow inlets and bays
Sandbanks
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Bottom trawling
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Report on the results of international research
project investigating the effects of different
types of fisheries on the North Sea and Irish
Sea benthic ecosystem. Provides an overview
of the effects of bottom trawling on marine
communities with chapters on physical impact,
direct mortality due to trawling, scavenger
response to trawling, comparison of undisturbed
and disturbed areas and long term trends in
demersal fish and benthic invertebrates.
Recommendations are made for future studies
including approaches to management and fishing
methods. For more conclusive evidence on the
long-term effects of beam trawling on benthic
ecosystem authors call for study of relatively
large areas closed to fisheries for many years.
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Lindeboom, H.J & de Groot, S.J. (Eds)
(1998) The effects of different types of fisheries
on the North Sea and Irish Sea benthic ecosystems.
RIVO-DLO Report C003/98
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REF: 79
Shallow inlets and bays
Sandbanks
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Suction dredging
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Comparative study of dredged and undredged
sites to investigate effects of suction dredging
on razor clam. Undredged site was characterised
by an absence of small razor clams, contained
the largest individuals, and a higher density
of razor clams. At the dredged site the population
had changed considerable in the 7 years of
spasmodic dredging. The most notable differences
were the absence of a middle size range of
clams and a decline in the number of large
razor clams. Shells from the dredged site
hand considerably more disturbance marks/damage
to the outer shell layer than at the control
site with 70% showing the highest level ie.
Deep clefts in the outer shell layer embedded
with sand grains.
Observations of the reburying of razor clams
collected by airlift and subsequently released
onto the surface of the sediment suggested
that they are highly vulnerable to attack
from predatory crabs and will experience a
high level of mortality after removal.
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Orphir Bay and Bay of Ireland, Orkney Islands
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Robinson, R.F. & Robinson, C.A. (1998)
The direct and indirect effects of suction
dredging on a razor clam (Ensis arcuatus)
population. ICES J.Mar.Sci 55:970-977.
[PR]
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REF: 80
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Gill net
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Survey of lost gill net over a three year
period using submersible. Known ghost net
sites at depths between 30m and 127m on a
variety of seabed types, surveyed quantitatively
by transects. 700m long ghost net on Stellwagen
Bank in a boulder field grading to silt-clay
substrate was visited on two occasions. Species
caught include dogfish, bluefish, lobster,
spider crab and edible crab. Hagfish were
often seen preying on the dogfish and bluefish.
A 470m long ghost net surveyed for two consecutive
years had dogfish as the most predominate
vertebrate catch. Cancer crabs were the most
common invertebrate catch. Codfish were not
seen in the ghost gillnet, nor were there
identifiable remains of cod at the base of
the net.
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Gulf of Maine
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Cooper, R.A. (1988) Manned submersible and
ROV assessment of ghost gillnets on Jeffries
and Stellwagen banks, Gulf of Maine. NOAA
Undersea Research Programme Research Report
88-4.
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