Chapter IX 
OUTER CONTINENTAL SHELF 
OIL AND GAS DEVELOPMENT 
Exploration and development of coastal and off- 
shore oil, gas, and hard mineral resources may 
adversely affect marine mammals and the ecosystems 
of which they are a part. Under the Outer Continen- 
tal Shelf Lands Act, the Department of the Interior’s 
Minerals Management Service is responsible for 
assessing, detecting, and mitigating the adverse effects 
associated with such activities in offshore waters 
beyond state jurisdiction. Under the Marine Mammal 
Protection Act and the Endangered Species Act, the 
National Marine Fisheries Service and the Fish and 
Wildlife Service are responsible for reviewing pro- 
posed actions and advising the Minerals Management 
Service and other agencies of measures needed to 
ensure that those actions will not have adverse effects 
on marine mammals or endangered or threatened 
species. The Commission reviews relevant policies 
and activities of these agencies and recommends 
actions that appear necessary to protect marine mam- 
mals and their habitats. The Commission’s activities 
in this regard in 1992 are discussed below. 
Proposed Offshore Lease Sales 
The Marine Mammal Commission, in consultation 
with its Committee of Scientific Advisors, reviews 
and comments on environmental impact statements 
and other matters concerning proposed outer continen- 
tal shelf oil, gas, and hard mineral lease sales. 
During 1992 the Commission commented to the 
Minerals Management Service on proposed lease sales 
in the Gulf of Mexico and on requests for information 
on possible lease sales in the St. George Basin, 
Alaska, and the Gulf of Alaska-Yakutat area. 
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Oil and Gas Lease Sales #142 and 143, 
Central and Western Gulf of Mexico 
Proposed lease sale #142, tentatively scheduled for 
March 1993, involves up to 5,194 blocks (approxi- 
mately 28 million acres) of submerged lands in the 
central Gulf of Mexico. Proposed sale #143, tenta- 
tively set for August 1993, involves the lease of 4,715 
blocks (about 25.8 million acres) in the western Gulf. 
In April 1992 the Minerals Management Service 
issued a draft environmental impact statement on the 
proposed lease sales and distributed it to the Marine 
Mammal Commission and others for review. 
The draft statement noted that 30 species of marine 
mammals, including the endangered West Indian 
manatee and six species of endangered whales, have 
been observed in the northern Gulf of Mexico. Of 
these, the sperm whale is the most common endan- 
gered marine mammal in the proposed lease sale 
areas. The most common non-endangered marine 
mammal species in the area is the bottlenose dolphin; 
several distinct populations of the species may exist in 
the Gulf. 
The draft statement concluded that all alternatives 
under consideration would have “sublethal, chronic 
effects” on both endangered and non-endangered 
marine mammal species. It further concluded that the 
proposed action, combined with other activities in the 
affected areas, cumulatively could cause declines or 
changes in the distribution of both endangered and 
non-endangered marine mammals, and that such 
changes could last more than a generation. 
