The survey team has been working at
full steam over the last couple of days making excellent progress. We
have completed the Central Fladen site and Western Fladen site, and
are now progressing quickly through the final South East Fladen site.
We’ve had very varied weather with the day shift getting lucky with
a burst of bright sunshine, as well as winds exceeding 40 knots, and
night shift witnessing a brief flurry of snow.
Nice seascape
The South East Fladen site has mud
sediments similar to the other sites with perhaps slightly less sand.
There have been no tall sea pens found in either the grabs or the
video footage, but the slender sea pen, Virgularia mirabilis,
can be seen in abundance. At present, Central Fladen site is the only
one of the three to contain the tall sea pen. V. mirabilis is
locally common on all coasts and is found at depths of 10-400m. It
can grow up to 60cm long and is able to withdraw into the sediment
when disturbed.
Photo of seapen in 1mm fraction of grab
Looking at maps of fishing activity
over the last five years, it appears that this area of the Fladen
grounds has been fished more heavily relative to the other sites, so
we expected to see evidence of this on the seabed. On a few of the
camera tows there were as expected a few obvious trawl marks in the
mud with more marks that appeared to be older and that had started to
backfill with mud. It was clear to us how busy this area usually is
as, whilst we were sampling, there were several fishing vessels, a
number of oil platforms and a drilling boat in the vicinity.
Image of tankers and platform
The fishery in this region generally
focuses on catching the Norway lobster (Nephrops norvegicus),
although bottom-dwelling fish may be caught also be caught in the
net. We captured a number of fish and shrimp on camera, but the
Norway lobster remained elusive leaving only burrows as evidence of
its presence. Nephrops live in a gallery burrow that can be
very large, with tunnels over a metre in length and up to 10cm in
diameter. The burrows have a number of entrances and it is possible
to estimate the number of animals from the number of burrow entrances
sighted on a video tow, though this is problematic as other species
also create burrows in this habitat. For example, burrowing crabs
such as Goneplex rhomboids, have also been seen during this
survey and create burrows similar to Nephrops, though slightly
smaller. Marks observed near the entrance to the burrow can also be
used to tell if the burrow is still occupied.
Juvenile dab (Limanda limanda) and pelican's foot (Aporrhais serresianus)
Grey gurnard (Eutrigla gurnardus)
