Section 1 Introduction - National Marine Fisheries Service - NOAA

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NBK at Bangor EHW-1 Pile Replacement Project Final <strong>Marine</strong> Mammal Monitoring Report Summary of Quantitative Analysis. Figure 18. Pinniped Behaviors by Construction Type Because of the relatively small number of harbor porpoises observed during pile driving events, no clear cetacean behavior patterns emerged with distance from pile. Pinnipeds were more likely to engage in all activities as distance to the pile increased. There was an increase in cetacean and pinniped foraging behaviors during construction as compared to non-construction periods. Both cetaceans and pinnipeds were more likely to swim during construction, and pinnipeds were slightly more likely to enter the water, dive, look and forage during construction. Cetaceans were most commonly observed swimming before, during and after construction, and an increase in swimming activity was observed during construction as opposed to just before and just after construction. Pinnipeds most commonly dove, looked, traveled, sank and swam in conjunction with construction activities. A general increase in these activities was noted during actual construction, as opposed to just before and after construction periods. Pinnipeds were more likely to look, sink and dive just after construction as opposed to just before construction. Pinnipeds and cetaceans were more often observed swimming during vibratory procedures than during other types of construction. Generally, more behavior categories were observed during vibratory pile driving, likely because this type of pile driving typically lasted longer than the soft starts to vibratory pile driving, which provided more opportunities to observe marine mammal behavior. Vibratory drives lasted up to 41 minutes, while most soft start events occurred only over a 3- to 4-minute timeframe. Therefore, there was typically more time to collect marine mammal observations during vibratory drives than during soft starts. Bangor, Washington 62
NBK at Bangor EHW-1 Pile Replacement Project Final <strong>Marine</strong> 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 Bangor, Washington 63
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Section 1 Introduction - National Marine Fisheries Service - NOAA

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