10 MARINE MAMMALS AND SEA TURTLES - Hebron Project

Hebron Project Comprehensive Study Report
Marine Mammals and Sea Turtles
10.5 Environmental Effects Analysis and Mitigation
Potential environmental effects on marine mammals and sea turtles during all
phases of the Project are discussed by Project phase and summarized at the
end of the chapter.
10.5.1 Construction and Installation
10.5.1.1 Change in Habitat Quantity
Nearshore
In the Nearshore Study Area, the bund wall footprint represents unavailable
habitat for marine mammals, although the shallow water depth would prevent
most marine mammals from occurring there even in the absence of the bund
wall. Thus, bund wall construction will result in minimal habitat loss for the
Marine Mammal and Sea Turtle VEC.
The removal of the bund wall in the Nearshore Study Area could make
previously unavailable habitat accessible to marine mammals. However, this
habitat will be in shallow water (and thus less preferable to most marine
mammals, as noted above) and disturbed. Thus, most marine mammals
would not preferentially use this habitat and it is expected to result in
negligible habitat loss for Marine Mammal and Sea Turtle VEC.
Offshore
The footprint of the Hebron Platform in the Offshore Project Area would
occupy a very limited area that may be used by pelagic and migratory marine
mammal and sea turtle species. Thus, the placement of the Hebron Platform
at the offshore site location will result in minimal habitat loss for marine
mammals and sea turtles.
Excavated drill centre(s) dredging may occur over a limited area in the
Offshore Study Area that may be used by pelagic and migratory marine
mammals and sea turtles. Species that are primarily benthic foragers (e.g.,
some phocids) would be most affected by a disruption in benthic habitat.
However, excavated drill centre(s) dredging in the Offshore Study Area will
likely result in minimal habitat loss for marine mammals and sea turtles.
10.5.1.2 Change in Habitat Quality
This effect category includes interactions that may result in physical/
physiological effects which occur as a result of a change in habitat quality.
Activities that are most likely to affect marine mammals and sea turtles are
blasting, pile-driving, and seismic surveys which produce impulsive sound
levels high enough to cause physical/physiological effects in marine
mammals (and likely sea turtles). As discussed in detail below, sound levels
thought high enough to cause a ―change in habitat quality‖ typically occur
very close to the sound source. The following section also summarizes
relevant mitigation measures which will be used during the Project. These
10-36 June 2010