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
Natura 2000 Habitats &
Further reports of otter deaths in fyke nets
and creels. These include 2 males in fyke
nets in the upper Ythan estuary after nets
in the river for only 3 days, indicating the
speed at which an eel fyke net will operate
as an otter trap in a catchment with normally
high otter density. Also reports the release
of an otter from a fyke net providing an example
of otter surviving capture when in shallow
water if struggles bring the cod-end to the
Deaths in creels reported from a lobster
creel in Scapa Flow, crab creel off Isle of
Arran and prawn creel off Skye.
Data confirm the potential of eel fyke to
attract and kill otters living at very low
density. Also appears to be considerable attraction
when silver eels begin their seasonal migration
- August/September on East Coast, October/November
in Severn. This must be one of the last opportunities
for otters to feed on eels in quantity before
capture becomes too difficult until spring.
Overall monthly distribution of all drownings
in fykes, creels and fish traps shows a marked
concentration in autumn and winter. Partly
explained by seasonality of fishing but also
when main food may be reduced for seasonal
Four otter guard test results shows only
a significant difference with the square guard
but only approximately 17% reduction. This
guard is used by the Danes as mandatory on
fyke nets. They have been mandatory in some
UK regions since the 1980's.
Crustacean trap problem still unresolved
and an issue on the rocky coasts of NW Scotland,
the Northern and Western Isles.
Ythan Estuary, Scapa Flow, Isle of Arran
and off Skye
Jefferies D.J. (1989). Further records of
fyke net and creel deaths in British otters
Lutra lutra with a discussion on the
use of guards. Journal of the Otter Trust.
Shallow inlets and bays
Review of data on penetration of depth of
ticklers and chain arrays of beam trawls.
Habitat effects - Under normal working
conditions beam trawls influence only the
top layers of the sea bed up to 30mm on muddy
ground and up to 10mm on sandy ground. Summary
of results to date suggest average penetration
depth 4-7cm. The depth depends on the bottom
type and structure of the ticklers and does
not always penetrate as the gear moves over
the seabed at speeds of 6-7 knots.
Groot S.J. de (1995). On the penetration
of the beam trawl into the sea bed. ICES C.M.
Shallow marine inlets and
Trammel nets and gill nets (discarded)
90m long gill net (100mm diameter mesh) and
trammel net (100mm with 600mm diameter outer
mesh) set by commercial fisherman and cut
at one end to simulate net loss. Survey of
catches by direct observation, still and video
photography for the following 9 months.
Species and community effects - Both
nets caught large numbers of elasmobranchs
which took about 3 weeks to decompose.
Gadoids were eaten within 72hrs therefore
not possible to tell how many were caught
throughout the observation period and estimates
were considered by authors to be conservative.
Initially both nets caught more fishes than
crustaceans but by 20 days crustacean catch
was greater than fishes and was greatest 43
days after initial deployment. Catch per 24hr
period declined with time and for fish was
nearly zero at 70 days for gill net and 22
days for trammel net. Catch per 24hr for crustaceans
remained higher than for fish for both nets
throughout the study. Reduction of catch rate
probably linked to reduction in net size and
degree of entanglement. Overall catch over
the 134 day experiment was 261 animals in
the gill net and 292 in the trammel net.
Maja squinado and Scyliorhinus
canicula were the 2 species most commonly
caught in both nets. Other species caught
were lobster, brown crab, swimming crab, Nurse
hound and Smooth hound. All the crustaceans
caught known to scavenge carrion. Other scavengers
also aggregated to feed on the animals in
the nets included A. rubens, M. glacialis,
O. fragilis (in large swarms) and E.
esculentus. Three shags were also caught.
When nets retrieved (3 months after last survey)
2 spider crabs, previously marked were still
alive after more than 102 days in the net.
Towards the end of the experiment the free
end of the nets began to roll up reducing
the total length of net.
Authors conclude that total catch of animals
during life of a net may be considerable as
in the present study but will depend on local
fauna, habitat type and environmental conditions
at the site.
St Brides Bay, Southwest Wales
Kaiser M.J., Bullimore B., Newman P., Lock
K. & Gilbert S. (1996). Catches in 'ghost
fishing’ set nets. Marine Ecology Progress
Series. 145: 11-16.
Shallow bays and inlets
Experimental work in situ and in laboratory
to evaluate the importance of the upwelling
of sediment during dredging and, in particular,
the amount of sediment particles, nutrients
and oxygen consuming substances released during
dredging as these factors can effect macrophyte
and phytoplankton growth as well as affecting
fish and bivalves.
Habitat effects - Preliminary results
suggest a minimum flux of 2km2,
corresponding to about 0.9cm penetration of
the gear. The release of particles, nutrients
and oxygen-consuming substances seems to have
little effect on the overall environmental
conditions in the fjord. Where 10-15 boats
dredge for several days, authors note that
this will alter the local concentrations of
nutrients and suspended matter directly, but
the effect would probably only be visible
or significant, during the dredging operations.
Total annual release of suspended particles
shown to be relatively unimportant compared
with total annual wind-induced resuspension
and release of nutrients compared to load
Species and community effects - the
effects are probably much more severe on the
ecosystem by changing the bottom flora and
fauna which may in turn affect water quality.
If natural bottom community cannot be established
the areas will be characterised by low biodiversity
and by opportunistic species dominated by
young individuals of small sizes. Overall
environmental effects of this disturbance
in Limfjorden is not fully understood.
Dyekjaer S.M. Jensen J.K. & Hoffman E.
Mussel dredging and effects on the marine
environment. ICES C.M. 1995/E:13 ref.K.
Discards and offal from several fisheries
Data from a study of scavenging seabirds
in the North Sea and review of literature
on quantities of discards. Fishery waste from
North Sea fishery is important to seabirds.
The sources evaluated here are demersal trawlers
and seiners catching gadoids, pelagic trawlers
and seiners, and beam trawlers. Authors estimate
quantity available amounts to around 62,800t
offal, 262,200t roundfish, 299,300t flatfish,
15,000t elasmobranchs and 149,700t benthic
invertebrates per year. Beam trawls have the
highest rates of discards of fishing fleets
in the area. Discard fraction is dominated
by flatfish which are less favoured by seabirds
potentially supported by fishery waste in
the North Sea estimated to be roughly 5.9
million individuals in an average scavenger
community. Discards and offal may easily support
all scavenging seabirds in southern and southeastern
sub-regions of the North Sea for example but
only half in the northwest region.
Garthe S, Camphuysen K.C.J. & Furness
R.W. (1996). Amounts of discards by commercial
fisheries and their significance as food for
seabirds in the North sea. Marine Ecology
Progress Series. 136:1-11.