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Satellite tagging of Harbour and Grey seal at Rødsand
At the western tip of Rødsand sandbank, vest of Gedser, a seal sanctuary has
been established to which access is prohibited between March 1 and September
30. The Rødsand area is the most important haul-out and breeding site for Harbour
Seals (about 250) in the western Baltic Sea. The area also has the largest stock
of grey seals in Denmark (about 25). Seals also haul out on the stone reef at
Vitten about 10 km west of the seal reserve at Flintehorne Odde about 5 km north
of the seal reserve.
In the years 2002 to 2005 a total of 72 windmills will be build at Rødsand.
In the permission to build the Rødsand windfarm a specific condition states
that the construction phase must not result in considerable changes in the distribution,
diurnal behaviour, and haul-out places in the seal sanctuary from 1 March to
1 October. The condition is not specific but to meet this condition in broad
terms we will study the seals at individual level (changes in area usage), at
stock level (changes in diurnal behaviour), and at population level (changes
in the use of haulout sites). The construction of the windfarm will cause a
lot of disturbances of the area but the windmills itself will cause a lot of
noise when build. The noise will be caused when the wind passes the blades and
the base of the windmill, which transmits vibration out into the water.
Hypothesis
The three proposed studies described below will constitute the baseline
for testing the following hypothesis:
· The distribution of individual harbour seals while at sea will not change
significantly in the Rødsand area during and after construction of the windfarm.
· The diurnal behaviour of harbour seals will not change significantly at the
Rødsand seal sanctuary during and after construction of the windfarm.
· The use of haul-out sites in the Rødsand area by harbour seals will not change
significantly during and after construction of the windfarm.
Methods
The seal monitoring program for Rødsand consists of three projects that are
described in details below: Satellite tracking of individual seals, video monitoring
of the seals hauling out in the sanctuary, and aerial surveys of all haul-out
sites in the area.
Satellite tracking of Harbour Seals
Harbour Seals are very shy animals and therefore very difficult to study in
the wild. The best way to study their movement will be to attach satellite transmitters
to the animals. The transmitter is glued onto the head of the seals. The movement
of each individual seal is then followed by satellites over a period of up to
10 month (until the yearly moult in July/August where the transmitter falls
off). Data on movements (location) are logged automatically and received on-line
over the Internet.
We are expecting to catch 10-15 seals every year until 2005 and attach satellite
transmitters to them. The results might reveal a change in areas used be the
seals or show the use of alternative haul-out or breeding site.
Similar windfarm projects are planed for Horn Reef west of Esbjerg.
The project at Rødsand windfarm is sponsored by the energy concern E2
and administrated by SEAS.
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NERI Technical Report
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Movements of seals from Rødsand seal sanctuary monitored by satellite telemetry.
Relative importance of the Nysted Offshore Wind Farm area to the seals. By Dietz, R. m.fl. (2003).
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