**REPORT TITLE**: The Navarin Basin Environment and Possible
Consequences of Planned Offshore

Oil and Gas Development‑‑Synthesis Meeting.

**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): Navarin Basin.

FISCAL YEAR(S) OF PROJECT FUNDING: 1983; 1984.

COMPLETION DATE OF REPORT: May 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)\*: L. Jarvela, M. Pelto, R. Peterson, T.
Sample, A. Springer, J. Strauch, F. Thorsteinson, L. Thorsteinson.

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

ACCESS NUMBER:

**BACKGROUND**: The Navarin Basin, located on the Alaska Bering Sea
Outer Continental Shelf (OCS), was first targeted for oil and gas
leasing in 1979.  In April 1984, the first lease sale (Sale 83) for the
Navarin Basin Planning Area was held by the U.S. Department of the
Interior.  Prior to this sale, and prior to the release of a draft
Environmental Impact Statement for this area, a synthesis meeting was
held to evaluate the state of knowledge concerning environmental
consequences of oil and gas activities in Navarin Basin.

**OBJECTIVES**: (1) To assemble and review information on environmental
hazards and potential impacts on fishery resources, marine birds, and
marine mammals related to oil and gas activities in the Navarin Basin.

**DESCRIPTION**: In October 1982, a meeting was held by the OCS
Environmental Assessment Program (OCSEAP) to review and synthesize
available environmental information pertaining to Navarin Basin,
Alaska.  Summaries of major findings were organized by topic into
chapters: geography and physiography; geology; meteorology, sea
conditions, and sea ice; oceanography; lower trophic levels; fishery
resources; marine birds; marine mammals; and oil and gas development and
related issues.

**SIGNIFICANT CONCLUSIONS**: The most significant environmental hazards
to offshore oil and gas development in Navarin Basin were winds and
waves, superstructure icing, and sea ice.  St. Matthew Island is an
important nesting area for breeding birds, a haul‑out area for marine
mammals, and a region where endangered bowhead whale occur during
winter.  Consequently, this island could be particularly sensitive to an
oil spill (depending upon the season).  In Navarin Basin proper, low
densities of pelagic seabirds would not be particularly susceptible to a
major oil spill.  Egg and larval stages of commercially important fishes
are most vulnerable to oil spills.  Based on current statistics, minimum
expected oil spills (1,000 bbl) would range from two to nine, and
maximum expected spills (10,000 bbl) range from one to four, over the
expected 15‑ to 25‑year lifetime of the Navarin Basin oil and gas
activity.  The fate of spilled oil will depend on prevailing
oceanographic conditions for degradation and transport of the spill. 
Drilling fluid discharges will not present a significant problem unless
oil‑based muds are discharged.

**STUDY RESULTS**: Navarin Basin sediments are Cenozoic and Mesozoic in
age and up to 15 km thick, representing a volume of greater than
400,000 km^3^.  Grain size decreases and organic content increases to
the west across the Bering shelf.  Generally, sand and silt occur on the
shelf edge and on the upper slope and in the heads of submarine
canyons.  Sediments have accumulated at a rate of 10 to 25 cm 1,000
yr^-1^.  Shelf sediments typically have undrained sheer strengths of 2
to 22 kPa.  Limited data suggest gas charged sediments, slumps, slides,
and sand waves occur on the Navarin OCS.  Major seismic faulting has yet
to be detected in the study area.

Monthly mean atmospheric temperatures range from ‑17C in February to
8C in July; mean monthly precipitation ranges from 113 cm in September
to 9.4 cm in April.  Fog results in limited visibility during summer
months.  Surface winds are predominantly northeasterly during winter
(mean 11 m s^-1^) and evenly distributed over all directions during
summer (mean 8 m s^-1^).  Storms are usually associated with a low
pressure region over the Aleutian Islands, are more frequent during
winter months, and usually move from west to east generating potentially
hazardous wave conditions.  Large ice floes originating from the
marginal ice zone are transported by south and southwest prevailing
winds.

Navarin Basin is divided into three hydrographic domains: mid‑shelf,
outer shelf, and oceanic.  Upper water layers are mixed by surface winds
and lower layers are driven by tidal forcing.  Tidal currents in Navarin
Basin range from 3 to 10 cm s^-1^ with tidal excursions of only 5 km
when all constituents are considered.  Semidiurnal tides were the
primary driving force during summer.  Winter circulation is primarily
affected by the ice front position and observed temperature, salinity,
and current fields.

Microbial populations attain higher levels in the sediments than in the
water column.  Phytoplankton occur along the ice‑edge and at the shelf
break; both populations are comprised of particular diatom species. 
Daily productivity estimates range from 143 to 630 mg C m^-2^ while
daily ice algal production averages 2.2 mg C m^-2^.  Open ocean
zooplankton communities are primarily large grazing copepods;
consequently, minimal carbon escapes the upper 200 m.  The inner shelf
zooplankton assemblage is characterized by inefficient grazers (small
copepods) that allow most phytoplankton to sink and enrich the benthic
zone.  Benthic communities segregate by water depth; in 100 to 200 m,
123 species are known with common components being polychaetes,
amphipods, shrimps, echiuroid worms, pelecypods, ophiuroids, and
priapulid worms; in 80 to 103 m depth, 48 infaunal speces are known. 
Infaunal biomass and species richness are higher on

the outer shelf and slope and lower on the inner shelf portions of
Navarin Basin. 

Most infaunal species are deposit feeders and to a lesser extent filter
feeders.

Of the approximately 300 fish species known from the Bering Sea, one
herring, five salmon, three codfish, nine rockfish, one sablefish, one
greenling, and eight flounder species are commercially exploited in the
Navarin Basin.  Pollock, flatfishes, and Pacific cod comprise the major
portion of the foreign and domestic commercial catch.  The largest
reported catches of groundfishes (\>20,000 tons) were from near the
shelf break.  There is no present commercial crab fishery in Navarin
Basin; however, king and tanner crabs are taken as a by‑catch during
trawling operations.  As many as 192 vessels fish in Navarin Basin.

The avifauna of Navarin Basin include seabirds, waterfowl, and shore
birds.  Seabirds, the most abundant group found in the study area, are
distributed in three domains: oceanic, slope, and shelf.  The three most
important seabird breeding areas in the Bering Sea (Pribilof Islands,
St. Lawrence Island, and St. Matthew Island) are east of Navarin Basin. 
Predominant seabirds breeding at these sites are auklets, cormorants,
fulmars, glaucous gull, kittiwakes, murres, pigeon guillemot, and
puffins.  Cliff‑nesting auklets and murres are the most abundant
seabirds on all islands.

Marine mammal species occurring in the Bering Sea include: six baleen
whales (bowhead, fin, gray, humpback, minke, and right); six toothed
whales (beluga, sperm, killer, Dall porpoise, Bering Sea beaked whale,
and Bairds beaked whale); two eared seals (northern fur seal and Steller
sea lion); four hair seals (ribbon, ringed, spotted, and bearded); and
walrus.  Factors affecting their spatial and temporal distribution
include ice cover, prey availability, and water depth.  Baleen whales
traverse Navarin Basin usually during winter months and feed on
invertebrates and occasionally fishes.  Toothed whales mostly feed on
fishes and squid, with the exception of killer whale which consume other
mammals and large fishes.  Seals generally prey on pelagic and
semidemersal fishes, while bearded seal and walrus rely on benthic
invertebrates as food.

A major oil spill in Navarin Basin could affect regional biota (marine
birds, marine mammals, and commercially important fishes and
shellfishes) depending on geographic location and season.  Land‑based
support activities could also present environmental problems depending
on location and extent of development.  Direct conflicts between oil and
gas related structures and commercial fishing interests are also
possible within Navarin Basin.

**STUDY PRODUCT(S)**: Jarvela, L. E. (ed.).  1984.  The Navarin Basin
Environment and Possible Consequences of Planned Offshore Oil and Gas
Development.  A final 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. 
156 pp.

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