**REPORT TITLE**: Proceedings of a Synthesis Meeting: The North Aleutian
Shelf Environment and

Possible Consequences of Offshore Oil and Gas Development.

**STUDY TITLE**: Outer Continental Shelf Environmental Assessment
Program‑‑Management

Functions‑‑Synthesis Meetings.

CONTRACT NUMBER(S): Part of Outer Continental Shelf Environmental
Assessment Program

(OCSEAP) interagency agreement(s).

SPONSORING OCS REGION: Alaska.

APPLICABLE PLANNING AREA(S): North Aleutian Basin.

FISCAL YEAR(S) OF PROJECT FUNDING: 1982.

COMPLETION DATE OF REPORT: March 1984.

COST(S): Costs of meeting(s) and report development are part of OCSEAP
management costs.

PROJECT MANAGER(S): Outer Continental Shelf Environmental Assessment
Program (OCSEAP).

AFFILIATION: National Oceanic and Atmospheric Administration.

ADDRESS: 701 C Street, Box 56, Anchorage, Alaska 99513.

PRINCIPAL INVESTIGATOR(S)\*: D. Armstrong, C. Maner, M. Pelto, F.
Thorsteinson, L. Thorsteinson.

KEY WORDS: North Aleutian Basin; synthesis; meetings; biology; hazards;
fates and effects; birds; marine mammals; fish; subsistence;
hydrography; oil spill; trajectory.

ACCESS NUMBER: SR-003

**BACKGROUND**: The Outer Continental Shelf Environmental Assessment
Program (OCSEAP) holds meetings to evaluate environmental issues and
resource use conflicts anticipated to arise within Alaska OCS proposed
lease sale areas.  The North Aleutian lease sale was slated for April
1985 (Lease Sale 92); therefore, a synthesis meeting regarding the North
Aleutian Shelf environment and possible consequences of offshore oil and
gas development was held in Anchorage, Alaska on 9 to 11 March 1982.

**OBJECTIVES**: (1) To review environmental and resource use information
for the North Aleutian Shelf; and (2) To identify potential effects of
offshore oil and gas development.

**DESCRIPTION**: Environmental data were evaluated in the light of the
proposed oil and gas leasing on the North Aleutian Shelf.  Meeting
agenda included: transport and fate of spilled oil, coastal habitats and
species, and fishery resources.

**SIGNIFICANT CONCLUSIONS**: Winds and tides force the circulation of
the shelf waters of the North Aleutian Shelf.  Winter storms can
generate severe waves in unprotected coastal areas.  Ice cover occurs in
northern waters of the North Aleutian Shelf in winter.  Coastal habitats
and estuaries are used as nursery, migratory, and spawning areas for
fishes and invertebrates; staging areas for shorebirds and water fowl;
and feeding areas by marine mammals.  In Izembek Lagoon, high eelgrass
production gives this area particular ecological significance.  Another
vulnerable area, Unimak Pass, serves as a major migratory corridor for
marine mammals migrating to and from the Bering Sea.  Coastal streams
draining into the proposed lease area are the spawning grounds of
chinook, coho, chum, pink, and sockeye salmon, which contribute to an
important domestic fishery.  A multinational groundfish fishery based on
pollack, Pacific cod, yellowfin sole, and other flatfishes exists on the
North Aleutian Shelf.  Trajectory analysis indicates that oil spilled in
the northwesterly portion of the lease area could strike the north coast
of the Alaska Peninsula at all times of the year.

**STUDY RESULTS**: Oil spill trajectories indicate that oil spilled on
the North Aleutian Shelf would respond directly to and be controlled by
ambient wind velocities.  In summer, prevailing southerly winds
(5 m s^-1^) would move spilled oil to the northeast into Bristol Bay at
6 km day^-1^.  In winter, prevailing northerly winds (10 to 15 m s^-1^)
would move spilled oil west‑southwest into the Bering Sea.  Under summer
conditions, oil spilled on the North Aleutian Shelf would lose volatile
components within 10 days.  Most beaches have coarse‑grained sands of
intermediate vulnerability and sensitivity to spilled oil regarding oil
persistence and contamination of indigenous biota.  Lagoon and bay
shorelines are much more sensitive to oil; contaminants would remain for
long time periods and biological losses could be substantial.

Winds and tides drive the circulation of the shallow continental shelf
waters of the North Aleutian Shelf area.  Mean currents are 1 to
6 cm s^-1^.  During winter months, local storms coupled with northerly
winds can generate severe waves in unprotected coastal areas.  Tides are
dominated by a semidiurnal bulge that enters the Bering Sea through the
central and western Aleutian straits as a free wave.  Tidal currents
range from 40 to 80 cm s^-1^.  Wind and tidal influences result in a
well‑mixed water column inside the 50‑m isobath.  The oceanographic
front lying along the 50‑m contour of Bristol Bay serves to divide the
North Aleutian Shelf into three distinct habitat zonations: offshore,
coastal, and estuarine.

The offshore (50 to 100 m depth) habitat is characterized by a diverse
benthic community constantly enriched by settling phytoplankton which is
inefficiently grazed by zooplanktonic herbivores.  Demersal fishes and
crabs are abundant in this area.  Seabirds, especially shearwaters, are
most abundant along the 50‑m isobath.  Walrus, sea lion, spotted seal,
and gray and beluga whales seasonally migrate across the offshore
habitat, usually in association with the ice edge.

Coastal waters also support rich infaunal communities, including high
standing stocks of clams, presumably the result of high detrital input. 
Herring, capelin, eulachon, and sand lance are common forage fishes that
use coastal areas as nursery, spawning, and migratory grounds.  These
fishes are the major food sources for several bird colonies along the
coast.  Seabirds that breed in these areas include cormorants,
kittiwakes, gulls, murres, and puffins.  Waterfowl and shorebirds are
also abundant on exposed coastal beaches.  The most common marine
mammals of the coastal habitat are harbor seal and sea otter, although
sea lion, walrus, and gray whale are also present.  The coastal habitat
is utilized as a migratory route for gray whale.

Estuarine habitats include the eelgrass beds of Izembek Lagoon, one of
the richest in the world with a daily production rate of 3.3 to
8.0 g C m^-2^.  Microbial degradation of eelgrass detritus is a major
functional process of the estuarine system.  Eelgrass meadows provide
habitat for juvenile fishes, crabs, shrimps, and other invertebrates and
the grass blades support diverse epiphytic assemblages.  Shorebirds and
water fowl use estuarine bays and lagoons as staging areas during spring
and fall; Nelson and Izembek Lagoons are especially important staging
habitats.  Harbor seal and sea otter are common estuarine mammals.  Gray
whale feed in Nelson Lagoon in summer and early fall.

Unimak Pass is one of the major migratory passages for bird and mammal
populations entering and leaving the Bering Sea.  Large aggregations of
seabirds, particularly sooty and short‑tailed shearwaters, are found in
or near the pass.  Endangered marine mammal populations (humpback, fin,
and gray whales, and northern fur seal) enter the pass during seasonal
migrations.  An oil spill at Unimak Pass during periods of peak animal
abundance could seriously affect regional populations.

The North Aleutian Shelf lease area, located within the Bering Sea, is
located within one of the world\'s most productive fishing grounds.  The
multi‑international groundfishery is situated on the western portion,
and an extremely valuable salmon fishery exists to the east in Bristol
Bay.  A region of significant red king crab harvest is within the lease
area.  Coastal and estuarine habitats of the North Aleutian Shelf are
most important as nursery, feeding, and migratory areas.  Five Pacific
salmon species, both seaward‑bound juveniles and returning adults, are
abundant in the area from May to September.  Adults move into Bristol
Bay, segregate into discrete spawning stocks, and ascend their
respective natal rivers.  During this mass inshore movement, the salmon
are most vulnerable to fishing pressure and potentially spilled oil. 
Emigrating juveniles are distributed in a coastal band approximately
60 km from shore.  The red king crab is the most vulnerable of the
commercially important species found on the North Aleutian Shelf.  This
crab\'s life cycle makes it most vulnerable; females are egg bearing for
11 months, followed by a 3‑ to 4‑month planktonic larval period.  An
environmental calamity (hydrocarbon contamination) during these times
could severely alter year class strength.  Other economically important
species occurring on the North Aleutian Shelf during one life phase or
another include pollock, Pacific cod, yellowfin sole, and other
flounders.  These species are harvested in large quantities by foreign
and domestic vessels operating within the Bering Sea.

**STUDY PRODUCT(S)**: Thorsteinson, L. K. (ed.).  1984.  Proceedings of
a Synthesis Meeting: The North Aleutian Shelf Environment and Possible
Consequences of Offshore Oil and Gas Development.  A report for the U.S.
Department of the Interior, Minerals Management Service Alaska OCS
Office, Anchorage, AK and the U.S. Department of Commerce, National
Oceanic and Atmospheric Administration, OCS Environmental Assessment
Program, Anchorage, AK.  NTIS No. PB84‑209428.  159 pp.

\*P.I.\'s affiliation may be different than that listed for Project
Manager(s).