Listed below is background material on the Gulf of
Alaska Large Marine Ecosystem. To keep this site current, users
are requested to provide updated information or links to the LME webmaster .
Brief Description:
The Gulf of Alaska Large Marine Ecosystem lies off the southern coast of Alaska and the western coast of Canada. It is separated from the East Bering Sea LME by the Alaska Peninsula. Its climate is sub-Arctic. The cold Subarctic Current, as it bifurcates towards the south, serves as the boundary between the Gulf of Alaska and the California Current LME. For a further description of the Gulf of Alaska’s major currents, see a NOAA report on the major currents of the North Pacific Ocean. The Gulf of Alaska Large Marine Ecosystem is sensitive to climate variations on time scales ranging from the interannual to the interdecadal. An article pertaining to this LME is by Brodeur et al., 1999. The article contains a map of large-scale near-surface circulation in the North Pacific Ocean.
I. Productivity:
The climate of the North Pacific is known to change
sharply over periods of decades, centuries and millennia, in concert with
climatic processes in other parts of the world, such as in the North Atlantic.
This has an effect on plankton production and plankton species composition.
The Gulf of Alaska LME is a Class I, highly productive (>300 gC/m2-yr)
ecosystem based on SeaWiFS global primary productivity estimates. It presents
a significant upwelling phenomenon linked to the presence of the counterclockwise
gyre of the Alaska Current (see NOAA, 2002). The LME’s cold, nutrient-rich
waters support a diverse ecosystem. Large-scale atmospheric and oceanographic
conditions affect the productivity of this LME. There is speculation about
what causes changes in the eastern bifurcation of the Subarctic Current into
the Alaska current, and the possible effects of these changes on biological
production in this LME. Changes in zooplankton biomass have been observed
in both the Gulf of Alaska LME and the California Current LME directly to
the South. These biomass changes appear to be inversely related to each other
(see Brodeur et al., 1999). A well-documented climatic regime shift occurring
in the late 1970s caused the Alaska gyre to be centered more to the east
(see Lagerloef, 1995). Brodeur and his co-authors hypothesize changes in
the future production of salmons as a consequence of long-term shifts in
the plankton biomass in the last decades. More information is available
on climate variability and climate change and its effect on the abundance
and production of marine organisms .
II. Fish and Fisheries:
The statistics of many agencies tend to apply to all of Alaska, which
makes a specific statistical breakdown for the Gulf of Alaska Large Marine
Ecosystem difficult to obtain. Catch composition in this LME is characterized
by a strong prevalence of the freshwater and diadromous group, and rich salmon
fisheries. The Gulf of Alaska LME supports a diverse ecosystem that includes
several commercially important fisheries such as crab, shrimp, pollock,
Pacific cod, mackerel, sockeye salmon, pink salmon and halibut. See FAO
2003, figure 15, for catch percentages in FAO’s 12 species groupings from
1990 to 1999. The catch trends for those 10 years are rather stable. Production
was 650,000 metric tons in 1990 and was about the same in 1999. For data
on king crab landings, tanner crab, and shrimp landings in this LME, see
Our Living Oceans, 1999. For an article about the walleye pollock in the
Gulf of Alaska, see Duffy-Anderson et al., 2002. For more information on
the production dynamics of Alaska salmon in relation to oscillating periods
of “warm” and “cool” regimes, see Francis, 1993, Francis and Hare, 1994,
and Hare and Francis, 1995. There is fishing on an industrial scale in the
Gulf of Alaska. The trawlers in this LME are also harvesting untargeted species,
some of which are not recovering. NOAA Fisheries in Alaska has more
information about trawl surveys conducted through 2002. For detailed
fish catch statistics for this LME, see data collected by the University
of British Columbia Fisheries Center . FAO also has compiled
statistics for the last decade. Click on the figure below for more details.
A recent summary of the Gulf of Alaska
Groundfish Fishery Management Plan is available. For more
information on NOAA's effort to ensure sustainable fish harvests,
see Alaska Fisheries Science
Center web site . For more information on fisheries, catch statistics,
regulations and restricted fishing areas, see the National Marine Fisheries Service’s
Alaska Regional Office .
III. Pollution and Ecosystem Health:
For information on coastal condition for all of Alaska,
see EPA, 2001. For statistics on harbor seals and harbor porpoises in this
LME, see Our Living Oceans, 1999. Pollution problems affecting the Gulf
of Alaska LME include predation by invasive species, discharges of oil products,
and industrial and agricultural contaminants that enter the LME through
a variety of pathways (ocean currents, prevailing winds). Prince William
Sound is routinely crossed by large oil tankers. In 1989 the Exxon Valdez,
off of the Port of Valdez, the terminus of the Trans-Alaskan Pipeline, spilled
11 million gallons of North Slope crude oil. This was the largest tanker
oil spill in US history and it contaminated 1,500 miles of the Gulf of Alaska’s
coastline. More than 10 years later there are concerns on the lingering
effects of the oil spill and the pockets of residual oil in the environment,
especially in the Western portion of Prince William Sound. The effects of
the oil spill interact with the effects of other kinds of changes and perturbations
in the marine ecosystem. More common than spills, however, are smaller discharges
of refined oil products, crude oil and hazardous substances. The
Gulf Ecosystem
Monitoring Program (2000)
has more information about pollution issues.
IV. Socioeconomics:
Several native communities rely for their subsistence
on the harvesting of marine resources (fish, shellfish, marine mammals,
birds). The economy of the coastal communities is based on commercial fishing
of pink and red salmon, fish processing, timber, minerals, agriculture and
tourism. Shellfish fisheries developed in the 1960s in the Gulf of Alaska
(see Our Living Oceans, 1999). Conflicts have emerged between coastal and
offshore interests. In 1998, there was an increase of visitors to over 1
million a year. The livelihood of 70,000 full-time residents living in the
area was directly affected by the Exxon Valdez oil spill. They had to overcome
the effects of the oil-related fish mortalities. Others using the area
seasonally for work or recreation were also affected.
Both the USA and Canada border the Gulf of Alaska Large Marine Ecosystem, which means that there are separate databases of information about government action and management plans. Public perception of the condition of the coastal waters and public health in this LME might differ. Moreover, statistics of many USA agencies tend to apply to all of Alaska. The North Pacific Fishery Management Council, in conjuction with NOAA has produced a Gulf of Alaska Groundfish Fishery Management Plan . The transboundary management of Pacific salmon (sockeye, chum, pink, chinook, coho, and steelhead salmon) has created a problem between the USA and Canada. The Pacific Salmon Treaty (1985) was meant to facilitate the management of these salmon stocks by preventing overfishing and providing for optimum production, but there have been disagreements concerning the equitable sharing of the salmon catch. Quotas are difficult to establish, given the fluctuations of salmon from one year to the next.
Articles and LME volumes:
Brodeur, RD, BW Frost, S. Hare, R. Francis and W.James Ingraham, 1999.
Interannual variations in
zooplankton biomass in the Gulf of Alaska, and covariation with California
Current zooplankton
biomass, In: Large Marine Ecosystems of the Pacific Rim: assessment,
sustainability and
management, Q. Tang and K. Sherman, Blackwell Science, pp. 106-138.
Collie, J.S. 1991. Adaptive strategies for management of fisheries resources
in large marine ecosystem. In
K. Sherman, L.M. Alexander, and B.D. Gold, eds. Food Chains, Yields,
Models, and Management of Large Marine Ecosystems. AAAS Symposium. Westview
Press, Inc. Boulder, CO. 225-242.
Duffy-Anderson, J., K.M. Bailey, L. Ciannelli, 2002. Consequences of
a superabundance of larval
walleye pollock, Theragra chalcogramma, in the Gulf of Alaska in 1981.
Mar. Ecol. Prog. Ser.
143:179-190.
EPA, 2001. National Coastal Condition Report.
FAO, 2003. Trends in oceanic captures and clustering of large marine
ecosystems—2 studies based on the
FAO capture database. FAO fisheries technical paper 435. 71 pages.
NOAA (National oceanic and Atmospheric Administration), 2002. Large Marine
Ecosystems of the world.
On line at: http://www.lme.noaa.gov/
Other references:
A National Atlas: Health and use of coastal waters, United States of
America; Fishery resource assessment
programs. 1988. Folio Map No. 7, Office of Oceanography and Marine Assessment,
NOS/NOAA, U.S. Dept. of Commerce.
Anderson, P.J. and J.F. Piatt. 1999. Community reorganization in the
Gulf of Alaska following ocean
climate regime shift. Mar. Ecol. Prog. Ser. 189:117-123.
Brodeur, R.D. and D.M. Ware, 1992. Long-term variability in zooplankton
biomass in the subarctic Pacific
Ocean. Fish. Oceanogr. 1:32-38.
Francis, R.C., 1993. Climate change and salmonid production in the North
Pacific Ocean. In Proceedings of
the Ninth Annual Pacific Climate (PACLIM) Workshop, K.T. Redmond and
V.L. Tharp, eds. Calif. Dep. Water Res. Techn. Rep. 34, pp. 33-43.
Francis, R.C. and S.R. Hare, 1994. Decadal-scale regime shifts in the
large marine ecosystems of the
North-east Pacific: a case for historical science. Fish. Oceanogr. 3:279-291.
Hare, S.R., and R.C. Francis, 1995. Climate change and salmon production
in the Northeast Pacific Ocean.
In Climate change and northern fish populations, R. Beamish, ed. Can.
Spec. Pub, Fish. Aquat. Sci. 121:357-372.
Lagerloef, G.S.E. 1995. Interdecadal variations in the Alask Gyre. J.
Phys. Oceanogr. 25:2242-2258.
Miller, A.J., D.R. Cayan, T.P. Barnett, N.E. Graham, and J.M. Oberhuber,
1994. The 1976-1977 climate
shift of the Pacific Ocean. Oceanography 7:21-26.
Our Living Oceans—Report on the Status of U.S. Living Marine Resources,
1999. NOAA. 301 pages.