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Part B - Technical instructions 
4 Marine mammals 
The investigations and monitoring relating to marine mammals comprise: 
• Surveys of abundance and distribution (Table 4.1). 
• Surveys of habitat use (Table 4.2). 
• Surveys of noise emission and immission (Table 4.3). 
Visual ship based and aerial digital surveys allow conclusions as to the abundance and distri 
bution of marine mammals and, at sufficient sightings, allow for estimates regarding the abso 
lute density of the populations. 
Stationary acoustic (click) detectors allow continuous monitoring of the habitat use of harbour 
porpoises. Acoustic detectors have to be deployed in addition to ship based and aerial surveys 
as a monitoring basis. 
During the construction and operation of wind turbines, a broad-band and tonal noise spec 
trum is likely to be emitted into the water. The estimate of potential impacts and hazard poten 
tial requires knowledge regarding the intensity of noise emissions and regarding the effective 
ness of stipulated preventive and noise reducing measures. Therefore, measurements of 
emissions at particular locations should be made during the construction and operation 
phases. 
The positioning of measuring instruments for recording underwater noise (Part A, Section 5) 
and survey start must be co-ordinated with the planning approval/approval authority at least 
eight weeks prior to installation. 
Depending on the characteristics of the construction site, the specification of emission method 
or in cases of cumulative impacts, additional measures may be prescribed to maintain 
efficiency and allow efficiency control. 
Table 4.1: Survey of abundance and distribution of marine mammals. 
Baseline study 
Construction 
phase 
Operation phase 
Objectives 
Stock inventory of marine mam 
mals in the assessment area in 
order to assess the ecological 
importance of the project area 
for marine mammals. 
Monitoring of 
the abundance 
and distribution 
of marine mam 
mals in the as 
sessment area 
to assess po 
tential impacts 
of construction 
work (in parti 
cular of pile dri 
ving). 
Monitoring of the abundance and 
distribution of marine mammals in 
the assessment area to assess 
potential impacts during the ope 
ration phase. 
Scope 
Ship based surveys take place exclusively within the scope of the avifauna survey. 
Throughout the year: 8-10 digital aircraft based suveys (video/photo), depending on 
project or area and seasonal occurrence of species. The aerial survey of marine mam 
mals takes place together with the aerial survey of resting birds (see table 3.1.1). 
Transects should cover at least 10 % of the assessment area.