Cetacean sigthings in North Sea

Marijke N. de Boer

Dataset credit

Marijke N. de Boer


Primary contact Marijke de Boer Wageningen Marine Research, University of Wageningen
Data entry Ei Fujioka Duke University



Minke whales and other marine mammals were recorded in the central
North Sea in an area characterised by frontal features and high productivity
northeast of the Dogger Bank (4677 km2). Survey efforts were carried
out from 28 March to 2 July 2007, at a finer scale than in earlier studies in
the region, using 2 vessels as platforms of opportunity and a dedicated line-
transect survey vessel following distance sampling methods. The high
density of whales indicated that this offshore bank slope is an important
spring habitat for minke whales in the North Sea. In total, 77 sightings of
minke whales comprising 130 individuals were recorded. The peak density
of minke whales was estimated to be 0.029 whales km–2 (minimum
estimate, 95% CI: 0.012 to 0.070) in May. During peak abundance, the minke
whales temporarily congregated in the area, suggesting that the whales
were taking advantage of the local spring abundance of sandeels. The
density found was higher than previous studies have suggested for the
central North Sea. The results correspond to recent observations of minke
whale redistribution within the North Sea, and these may be related to a
decline in sandeel availability elsewhere in the North Sea. Offshore banks
that aggregate prey may therefore become increasingly important feeding
habitats for minke whales and other top predators in the North Sea. The
observed habitat preference of minke whales along this offshore bank
appeared to be similar to that observed in coastal areas, and this suggests
some degree of generality regarding the preference for this type of habitat.


As part of a geophysical seismic survey, marine mammals observations were
carried out from three vessels: one seismic vessel, one supply vessel operating
well ahead from the seismic vessel. The third vessel, MV ‘Andfjord’, carried out
a dedicated Line Transect (LT) survey (23 April to 17 May). The LT vessel was
surveying at distances of ≥20 km away from the geophysical vessel and
followed predetermined line transects placed randomly in a zigzag pattern in
the central (German) part of the survey area.

Supplemental information





This section explains attributes included in the original dataset. OBIS-SEAMAP restricts the attributes available to the public to date/time, lat/lon and species names/counts only. Should you need other attributes described here, you are encouraged to contact the data provider.

Attributes described below represent those in the original dataset provided by the provider.
Only minimum required attributes are visible and downloadable online. Other attributes may be obtained upon provider's permission.

Attributes in dataset

Attribute (table column)Description
oidUnique ID number (generated by OBIS-SEAMAP)
sighting_numberSigthing number
dateDate of the sighting
timeTime of the sighting at GMT
vesselVessel name
latitudeLatitude in decimal degrees
longitudeLongitude in decimal degrees
speciesSpecies name
latin_nameScientific name
sp_tsnTaxonomic Serial Number added by OBIS-SEAMAP
total_numberGroup size
beaufort_windBeaufort sea state
geomGeometry field added by OBIS-SEAMAP
Marine mammals165
Sea turtles0
Rays and sharks0
Other species0
Non spatial0
Non species0
Date, Begin2007-03-31
Date, End2007-07-02
Temporal prec.111110
Latitude53.15 - 56.26
Longitude3.08 - 4.58
Coord. prec.5 decimal digits
Data typeAnimal sighting
Traveled (km)0
Contr. through
Sharing policy CC-BY-NC (Minimum)
Shared with OBIS
GBIF (via DOI)
See metadata in static HTML
See metadata in FGDC XML
See download history / statistics