spill are independent of the probability that a spill will 

 occur, and that it therefore is inappropriate to conclude that 

 the effects will be negligible or minor because the probability 

 of occurrence is negligible or minor. The Commission also 

 noted that some potential impacts are difficult or impossible 

 to identify or assess from available information. 



Therefore, in its letter, the Commission recommended that 

 the Minerals Management Service modify the Statement to acknow- 

 ledge uncertainties concerning the likely effects of the 

 proposed action and that the Final Environmental Impact State- 

 ment consider: (a) the possible effects on polar bears of 

 garbage disposal from drilling platforms; (b) the possibility 

 that oil spills, disturbances, etc . . will cause walrus, polar 

 bears, ice seals, and other species to move to adjacent areas 

 already occupied, thereby increasing animal densities in those 

 areas to levels that will damage or deplete food supplies; 

 and (c) the possible cumulative effects of subsistence harvest- 

 ing and other activities, as well as oil and gas exploration 

 and development, on bowhead and beluga whales, polar bears, 

 walrus, and seals. The Commission also recommended that the 

 Minerals Management Service consider developing and implementing 

 monitoring programs aimed at detecting unforeseen impacts 

 before those impacts can reach unacceptable levels. 



Proposed PCS Lease Sale #109 

 Chukchi Sea 



Lease Sale #109 is tentatively scheduled for May 1988. 

 It involves up to 5,448 blocks (approximately 29.5 million 

 acres) of submerged OCS lands in the Chukchi Sea off north- 

 west Alaska. Ten species of marine mammals, including four 

 endangered whales species (bowhead, gray, fin, and humpback 

 whales) are found in the sale area. The Minerals Management 

 Service prepared a Draft Environmental Impact Statement on 

 the proposed action, which was distributed to the Commission 

 and others for review and comment on 6 March 1987. The Draft 

 Statement concluded that possible effects of the proposed 

 activities on all species of non-endangered marine mammals 

 and on the endangered bowhead and gray whales are likely to 

 be minor, and that possible impacts on the endangered fin and 

 humpback whales are likely to be negligible. 



The Commission, in consultation with its Committee of 

 Scientific Advisors, reviewed the Draft Statement and provided 

 comments to the Minerals Management Service on 5 May 1987. The 

 Commission noted that the Statement provides a concise and 

 useful review of information on the abundance, distribution, 

 trophic relationships, and subsistence take of both non- 

 endangered marine mammals and endangered bowhead whales, and 

 that it also provides a reasonably thorough review of the 



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