Surveying for marine mammals in tidal streams - problems and possible solutions

1. Surveying for marine mammals
in tidal streams
Problems and possible solutions
Steven Benjamins, Ben Wilson, Jim Elliott,
Russell Leaper, Jonathan Gordon

2. Tidal-stream energy generation
in Scotland
Potential for significant expansion
(e.g. Sound of Islay test array)
Potential risks to marine mammals
(collision, habitat exclusion)
Assessment of relative © Hammerfest Strøm
abundance and habitat use on
site-by-site basis

3. Problems monitoring in tidal
streams
At high current speeds:
– Porpoises are even less visible
– Increased ambient noise may
mask calls

4. Porpoises with tide (flood)
Porpoises with tide (ebb)
Porpoises station to bottom
6 knots over the ground (GPS)

5. A multi-element approach (1)
Land-based visual
observations of particular
areas (as appropriate)
Visual observations from
survey vessel
– Go with current, but at an angle
– Repeat surveys through tidal 58°
cycle

6. A multi-element approach (2)
Passive acoustic monitoring:
– Towed hydrophone array (spatial
coverage)
– Moored porpoise click detectors
– (CPODs; temporal coverage)
– Drifting hydrophones (to address
water movement issue)
© Chelonia Inc.
© SAMS
Different approaches provide a range of perspectives!

7. We thank:
Cally Fleming, Robert Batty
Silurian Skippers: Dave Hannah & John Hill
Observers and crew esp. Nic Davies, Lucia Lopez &
Nienke van Geel
Funding from: