4.4.2. Hard Surfaces: Buoys and Anchoring Systems - Collision,
Entanglement and/or Entrapment
Issue: The deployment of structures in a previously clear area brings the risk of collision and/or
entanglement of animals; primarily the larger fish, the seabirds and the marine mammals.
Findings. Kaneohe Bay: The risk of cetacean entanglement was considered minimal for this
project because the four buoys were attached to the seafloor instead of being anchored by buoys
with lines, and the cable was intended to run along the seafloor. Entrapment risk was minimized
by buoy design, and collision risk was not assessed (Sea Sound Technology 2002). Makah Bay:
The Environmental Assessment concluded that risk of cetacean entanglement was minimal
because the exposure of a single buoy was low, and the anchor lines would have sufficient
tension to avoid the entanglement characteristically seen with smaller and lighter tensions (FERC
2006). Programmatic Draft EIS: The MMS PDEIS for alternative energy (MMS 2007) states
that wave energy facilities may have as many as 2,500 mooring lines securing the wave energy
devices to the ocean floor. Thus, marine mammals swimming through a wave energy facility
may strike and become entangled in these lines, becoming injured or drowning. Depending on
the species affected, entanglement may result in minor to major impacts to marine mammals.
Worldwide Assessment: This assessment found it likely that migrating gray whales would
interact with wave energy devices on the US West Coast and that entanglement in mooring
cables could cause an impact. It also found that seabird exposure would likely increase due to
attraction to fish responding to the Fish Attraction (or Aggregation) Devices (FAD) (see below)
effect (Michel et al. 2007). Reedsport Project: This document addresses the possible collision
or entanglement of cetaceans by recommending mitigation via acoustic "guidance" devices.
Seabirds are not expected to have significant collision risk because all structures will be large
enough to be visible. The document also states that design characteristics of the buoys
themselves will prevent hauling-out by pinnipeds (FERC 2007). Scottish Executive: This report
dealt with vertebrate collision risk in some detail, citing many conclusions of a supporting study
behavioral responses (Wilson, et al. 2007). The strategic environmental assessment concluded
that risk of collision for marine mammals and seabirds was very uncertain and that the
conclusion was made with very low confidence (Faber Maunsell and METOC PLC 2007).
Mitigation. Mitigation for collision and entanglement can include visual cues, such as highly
visible paints and acoustic "guidance" to cause animals to perceive the structures or avoid them.
Entanglement may also be avoided by using thick, high-tension mooring lines. Entrapment
mitigation may be achieved both by visual or acoustic avoidance, but more likely by appropriate
device design considerations.
So, given that this collision 'problem' isn't nearly as bad as was made out by Tomás, I tend to think that it's closer to a NIMBY issue.
The reason, then, that it's not a primary point to be made is mostly because it's demonstrably incorrect that 1) it's assuredly already a problem and 2) that the number of proposed units is near the number which is expected to cause a problem.
That said, here's some more from the 'Comments' section for 2008:
40 units in an area of ocean??? Within view of the coastal bluffs?
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