Section 1 Introduction - National Marine Fisheries Service - NOAA

NBK at Bangor EHW-1 Pile Replacement Project Final Marine Mammal Monitoring Report
Qualitative Observations
In addition to the quantitative results presented above, MMOs made a number of qualitative
observations on the movements and distribution of animals, and on the potential effects of
driving activities on marine mammal behavior. Within the EHW-1 structure, which contains
hundreds of pilings and a large overhead structure, MMOs documented the presence of at least
two “resident” harbor seals, repeatedly observed and easily recognizable by their distinctive
pelage patterns. These two animals, both juveniles, were constantly swimming into and out of
the pile driving and construction areas, as well as within other portions of the EHW-1 structure.
These two animals were observed during the entire duration of monitoring activities in EHW-1
PRP (approximately 4 weeks). Harbor seals spent more time in the vicinity of EHW-1 PRP, and
their use of space and diving/surfacing patterns suggested that they were foraging, rather than
simply transiting through the area. In addition, the two juvenile animals mentioned above were
directly documented foraging in and near the construction zone on several occasions, either
because they were observed with shells or fish in their mouths, or were seen nosing into the hard
growth on the pilings.
Observations at EHW-1 involved multiple observations on a daily basis of one or both of the
“resident” juvenile harbor seals within the 50m (164ft) shutdown zone, and at other locations
within hundreds of meters from the piles. Additionally, EHW-1 repairs involved a number of
other activities including welding; construction of scaffolding on newly driven piles; and the
presence and movement of boats and barges within a confined area. Thus, the number of
sightings available to develop qualitative observations was far greater, albeit with a smaller
number of individual animals. Generally, the “resident’ harbor seals showed little avoidance of
any of the areas of noise or disturbance, and instead often surfaced in areas of activity and then
remained either lying on their backs, or positioned vertically in the water, moving their heads
back and forth scanning the activity area. After 10-20 seconds, they would then dive and either
resurface in a new area or would not be resighted. The MMOs noted that these observations
were consistent with an interpretation of animal curiosity about the activity being conducted.
As a consequence of seals frequently moving into and out of the 50m (164ft) shutdown zone,
pile driving often did not begin and/or did not continue once initiated. Once the shutdown zone
was “cleared” (i.e., no animal within 50 m (164 ft) for 30 minutes, or if within 50 m (164 ft) but
then re-sighted outside the shutdown zone), animals seemed to keep from approaching the
shutdown zone during soft start events and pile-driving activities. However, on a number of
occasions they moved within 50 m (164 ft) of the pile, which resulted in a shutdown of pile
driving. At no time were either distress behaviors or rapid flight observed. Once pile driving
had ceased, the MMOs noted that animals moved back within 50 m (164 ft) of the pile that had
been driven within a few minutes of pile driving cessation. Again, these animals were positively
identified by pelage markings, and MMOs were confident that these animals tolerated multiple
weeks of pile driving activities without abandoning the construction area, or without exhibiting
distress or flight behaviors. Instead, animals maintained heavy use of the area, which may
indicate their habituation, or indifference, to noise and disturbance. Other harbor seals were also
observed within 100 m (328 ft) of pile driving locations before and during pile driving, with no
visible distress signs or active flight behaviors. California sea lions were only occasionally
sighted during monitoring at EHW-1 and were always in transit, generally moving from north to
south. Transiting did not appear to be impaired or accelerated by the pile driving activities. In
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