"opposed to the project moving forward without first resolving issues associated with our pre-existing rights [...] it will infringe on our pre-existing offshore oil and gas tenure rights in the area. This partial sterilization of our tenure rights..."
Sterilization? Good grief. What, like Naikun's project is some sort of corporate vasectomy?
The letter is copied to Naikun and to the Haida Nation - one nation among these bickering corporations which really does have pre-existing rights.
Specifically, the oil companies are concerned that construction and operation of the offshore wind farm will interfere with their right to perform seismic testing ("seismic acquisition" they call it) and to "construct infrastructure and conduct drilling and production operations"
The "mitigative measures" sought by Shell and Chevron are:
In a joint letter to the BC Environmental Assessment Office, regarding the 
