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8
Gaps in Knowledge and Recommendations
Both the gaps in our knowledge about the Bering Sea ecosystem and the research required
to fill those gaps are so extensive that a detailed elaboration could be a report in itself.
However, characterizing the general shortcomings of our past perspectives that contribute to our
present lack of understanding and specifying a list of priority research needs could help address
some of the most pressing issues concerning the Bering Sea ecosystem.
The biggest single impediment to understanding the causes of change in the Bering Sea
ecosystem (as well as in many other ecosystems) is the absence of an ecosystem viewpoint in
research and scientific analysis. Previous research has typically focused on individual species
populations, small subsets of the ecosystem, or short time periods. Such approaches have
reflected the narrow ecological and temporal focus and responsibilities of the individual
management agencies responsible for specific subsets of resources in this ecosystem. Such
partitioning of an ecosystem into separate species, or subsets of species, does not allow the broad
synthesis of information across all interacting and interdependent components of the ecosystem.
Such synthesis is required to properly interpret the dynamics of the system. The most significant
research recommendation that emerges from this study is to adopt a broader ecosystem
perspective in both science and management of the natural resources of the Bering Sea. Such
an approach makes sense scientifically and holds the greatest promise for unproved management
and understanding.
Even with adoption of an ecosystem perspective to synthesize information, ecological
science will never achieve complete understanding of what controls the dynamics of distributions
and abundances of species in any ecosystem. Gacs in knowledge will always be present and
, ~ ~ a- -- r--~-~~~ if---
unexpected phenomena will continue to arise. Such changes, if deemed important, will stimulate
demand for additional research, enhancing our understanding of causation and consequences.
The challenge to management and stewardship of ecosystems is therefore how best to manage
human activities given substantial uncertainty in the scientific understanding of the causes of
dynamic change in those ecosystems.
~ , ~ r ~ ~.
in part Because or uncersamplmg of marme ecosystems, there is probably greater
uncertainty about the causes of dynamic changes in ecosystems in the ocean than on land. The
vastness' isolation from human habitation, and large' three-dunensional domain of the open
oceans create an overwhelming problem in simply knowing the abundances and distributions of
species in the ecosystem. Although physical oceanographers have the technological capacity to
250
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Gaps In Knowledge and Recommendations
251
characterize ocean currents in three dimensions by use of acoustic Doppler current profilers, for
example, the development of analogous biological samplers (even those exploiting the same
acoustical principles) is in its infancy.
Nonetheless, despite substantial gaps in our understanding of the dynamics of marine
ecosystems, there is compelling evidence that changes in both the physical climate of the sea and
fishing have had large influences on the composition and dynamics of many marine ecosystems
(e.g., Sherman, 1991; Chapter 6). Again, distinguishing between effects of physical changes
and those of fishing (more broadly, exploitation of natural resources) was the central issue in
our evaluation of the causes of recent declines in certain marine mammals (Steller sea lions,
harbor seals, and fur seals) and seabirds (red- and black-legged kittiwakes, sea ducks, and
murres) over various expanses of the Bering Sea and adjacent regions.
A critical difference exists between these two kinds of potential causes of change in the
Bering Sea ecosystem. Changes in the physical climate of the sea occur largely, although not
completely, independent of human control, whereas exploitation of natural resources is directly
carried out by humans and theoretically can be controlled (in practice, control often is extremely
difficult). This difference potentially allows fisheries to be managed with attention to evaluating
rigorously the consequences of the exploitation (e.g., Peterson, 1993). This has been called
adaptive management (McAllister and Peterson, 1992; Walters and Hilborn, 1986). Under well-
designed fishing regulations (based on hypotheses about ecological causation), adaptive
management of fisheries can become an extremely powerful tool for improving our
understanding, not only of the impacts of fishing but also of the basic functioning of marine
ecosystems (Holling, 1993). Clearly, the potential for adaptive management of the Bering Sea
fisheries has not been adequately applied to develop the necessary understanding of the role of
fishing in contributing to ecosystem changes. These would especially include the disturbing
declines in many important marine mammals and seabirds.
Much of the research on the Bering Sea ecosystem to date has followed the traditional
reductionist path of trying to understand the mechanisms that drive the dynamics of this
ecosystem on various spatial and temporal scales. Such an approach has obvious value.
Elucidating fundamental interactions among components of the physical and biological
environment appeals to a large majority of scientists and promises the capacity to understand and
perhaps predict. Such research on basic processes should continue, but it should be
complemented by assessments of the effects of manipulating the system through fisheries-
management practices.
This effort must include the provision of resources sufficient for research to follow up
with evaluations of how variations in fishing affected the functioning of the system. It also must
examine the ecosystem's ability to sustain populations of key component species. For example,
the recent establishment of no-fishing buffers around important colonies of seabirds and marine-
mammal haulouts provides opportunities for exactly the sort of experimental adaptive
management that is required. However, there has been no experiment or dedicated research to
assess the role of fishing in declines of certain Important marine mammals and seabirds. The
U.S. National Marine Fisheries Service (NMFS) regulations of fishing were not designed with
experiment in mind, and little research support was provided to evaluate the effects of these
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The Bering Sea Ecosystem
changes in fishing practices. This is a wasted opportunity to realize an important aspect of
adaptive management; learning through rigorous evaluation of the consequences of management
interventions. These oversights must be corrected to achieve confident stewardship and
sustainable use of the living resources of this ecosystem.
To be effective, the adaptive management actions and research goals to be addressed
through intervention in fishing practices must be jointly planned by fisheries scientists, bird and
wildlife biologists, oceanographers, fisheries managers, and the users of the natural resources
on both sides of the Bering Sea. In using adaptive management to evaluate the role of fishing
in the ongoing declines of valued marine mammals and seabirds, any changes in regulation and
management of fishing must be carefully crafted. They should include tests of specific
hypotheses that relate to critical aspects of the species' ecology in the proper physical context.
For example, while average abundance of important forage fishes such as pollock may remain
high even with intense fishing when considered over the complete Bering Sea basin, dramatic
depletion of certain size (age) classes at certain times and in certain places is likely to occur as
a result of commercial fishing in this system. The creation, evolution, movement, and
transformation of those depleted patches will depend on both physical and biological processes.
Those local depletions may correspond with the seasons and locations where food limits one or
more important consumers of these forage fishes. For example, the need for abundant food of
high nutritive value around rookeries or other important foraging areas to nourish parents or
independent young may well present a conflict between fishing and sustained production of some
marine mammals and seabirds.
Design of adaptive fisheries management to test the relationship of local fishing to
successful passage through potentially critical life history stages must be achieved through
collaboration. The collaboration should take place among scientists of several disciplines and
fisheries managers, so that the management actions taken match the relevant biological time and
space scales. Thus experts on marine mammals and seabirds must participate early in the design
of the management plan, and agree that the plan is an appropriate test of the most important
hypotheses. The study plan developed must recognize relevant physical transport and mixing
processes as well. One set of adaptive management actions may not suffice to test all the
important hypotheses, several management interventions may be needed. Some disruption of
historical patterns of commercial fishing will necessarily occur in this process, but adaptive
management is the most rigorous, efficient, and effective means of evaluating the effects of these
fisheries on the broader ecosystem. Other indirect methods of testing for the effects of various
fishing practices will perpetuate the piecemeal efforts of the past, and will not dramatically
improve our understanding of the relationships until a great deal more money has been spent and
critical time for restoration has passed. Manipulation of the fisheries using a well-crafted
design, together with funding for ecological evaluation of impacts, represents the best way to
address these unanswered questions. It is important to keep in mind that fishing includes
commercial, subsistence, and recreational fishing, and that all of them to varying degrees affect
each other and the exploited organisms.
There are several additional research needs of high priority. One is the need for a better,
more complete retrospective analysis of the Bering Sea ecosystem and certain of its key
components. This analysis is especially critical for pollock, because of continuing uncertainty
over whether its present high abundance is a relatively recent phenomenon, or whether the
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Gaps In Knowledge and Recommendations
253
absence of pollock fishing before about 20 years ago gives a false impression of relatively low
pollock biomass in earlier years. The relationship between adult and ~ ~~
abundances also needs to be understood better. - ~ - ~ ~ ~
.. ~. . . .. .. . . . ..
Juvenile pollock
Resolution ot these and similar unanswered
bump Mu ~= ~c Mar; `;v~npv=~vn or one Bering pea ecosystem 's critical to
~1~:_ ~ 41~_ ._1~- _ _1~ - _= ^_ __ _ ~ ~
u~uc~vra~u~g ~c Up o~ top predators to prey resources and Questions concerning
natural versus human-caused fluctuations in species abundance
~- --O
The present monitoring of the Bering Sea ecosystem is inadequate to understand, let alone
predict, biological changes within it. In fact, there is no ecosystem monitoring. Only a few
components of the system are monitored at all, with insufficient attention to the broader context
of the ecosystem. We have little or no quantitative information on such critically important prey
species as capelin, sand lance, smelts, squids, and myctophids. Understanding and managing
an ecosystem without basic knowledge of the prey base on which the predator species depend
is virtually impossible.
Both conceptual and mathematical models of the structure and function of the Bering Sea
ecosystem must be developed and verified by comparison with field fiats tn arlv~nce
~1 _ _ _ 1~ , 1 ~, ~, ~. ~
~1 ~
ur~uers~analng or me ecosystem, lo TOCUS rurtner research on the most sensitive issues and to
guide adaptive management decisions.
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_ _ ___ ~^ ~ TV VIA ~ ~ AVER-Vat ~11~ TV
Such models are also necessary to design proper
ecosystem monitoring, Waco cannot be so extensive as to provide information on all elements
of the system. A sensible ecosystem monitoring strategy must be model-driven. For example,
a selection of specific seabirds and marine mammals may serve well as indicators of the forage
prey base of the entire ecosystem in a much more cost-efficient and biologically meaningful way
than direct monitoring of all prey populations. Monitoring a shallow-diving seabird such as a
kittiwake and a deep-diving seabird such as a murre might be one tool, for example, to monitor
offshore pelagic forage fish. Such suggestions need to be more completely developed to cover
the most important aspects of the ecosystem.
At present, there is no archive of information about the various databases that do exist
on certain aspects of the Bering Sea ecosystem. The sources and contact people for each
database need to be identified and compiled in a fashion that permits potential users to access
data. This is not to suggest that vast resources be spent in the creation of a comprehensive
database on the Bering Sea. In the modern era of distributed computing and information
highways, such an effort is not necessary. Ultimately, the use of geographic information system
technologies to achieve integration through data overlays on various scales of time and space
should be encouraged to move closer to the integration required for an ecosystem perspective.
Long-term monitoring of Important physical and biological components of the Bering Sea
ecosystem must be established to permit analyses of observed changes in the system and their
causes. The short-term perspective of almost all available data sets contrasts sharply with what
is known about the longer-term nature of many important climate changes and the population
dynamics of many long-lived organisms. Instead of initiating necessary long-term monitoring,
some of the most important long-term records are being abandoned, with grave Implications for
understanding and management of the system as a whole. For example, a long-term (30-year)
program of monitoring juvenile fur seal survivorship was abandoned in 1988 and should be
reinitiated. Other long-term monitoring programs need to be established through reference to
good conceptual models of the ecosystem.
~. ~ . ~. ~
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The Bering Sea Ecosystem
A major field research program is required to develop the necessary basic understanding
of how the physical conditions of the Bering Sea interact with the biological system to drive
changes in ecosystem dynamics. There has been a substantial research commitment to achieving
an oceanographic, process-based understanding of the eastern boundary current systems of
upwelling. In other ecosystems, these upwelling systems are critical to production of important
ecosystem goods and services. However, mechanistic understanding of the roles of climate and
physical oceanographic forcing relative to the predominantly buoyancy-driven currents of the
critical green belt of the Bering Sea is incomplete. This basic oceanographic research is central
to developing the conceptual and mathematical models for focusing research, monitoring, and
managing of this system.
A data rescue and archiving project should be initiated immediately to preserve
endangered ecological information that has been collected by individuals and institutions within
the borders of the former Soviet Union. The breakdown of institutional structures within Russia
and the republics threatens the loss of valuable information on components of the Bering Sea
ecosystem along the Asian coast. In this region of the Bering Sea, there has been virtually no
research by U.S. scientists. Furthermore, many data records that complement U.S. information
are also known to be in files within the former Soviet Union, often in such forms as
hand-written notes.
Further basic research on ecosystem dynamics is needed to address convincingly whether
ecological science can predict or even explain how a perturbation to an ecosystem cascades
through that system. The characteristics of an ecological system that will allow confident
prediction or explanation of cascading impacts should be identified. These questions need to be
addressed in marine pelagic ecosystems, where little, if any, research has ever taken a broad
perspective involving the dynamics of complete ecosystems.
Research is also needed to integrate traditional knowledge of indigenous peoples into the
body of scientific knowledge on the Bering Sea, to achieve both better scientific understanding
and better resource management. The traditional knowledge of native communities and the
acquired knowledge of fishermen and hunters represent valuable sources of information and
understanding.
Ecological research on the meaning of sustainability is necessary to address the question
of how to define sustainability under conditions of dynamic natural change in ecosystems. This
is an especially challenging question in ecosystems undergoing substantial changes in response
to major climate shifts, which force biological responses.
Management decisions concerning the Bering Sea ecosystem that affect many stakeholders
both within the region and in other parts of the world are made by local, state, regional, tribal,
national, and international entities. Good institutional structures should be designed to
coordinate the activities of these entities such that the views of all stakeholders can be heard, the
likely effects of alternative actions can be made known, and decisions can be reached. In
addition, research is necessary to design specific management regimes and regulatory tools (such
as area management, co-management, or individual transferable quotas) that are acceptable to
the stakeholders, enforceable, and capable of changing individual behavior such that the intended
objectives for resource use can be achieved. Improved knowledge of the ecosystem will have
little effect on resource use unless there are overall management structures that can implement
effective policies and overall communication structures that can facilitate exchange of knowledge
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Gaps In Knowledge and Recommendations
255
and understanding among different stakeholders. These considerations led the committee to
make the following recommendations.
RECOMMENDATIONS
Research
Adaptive Management
One research recommendation includes and influences all the others, and that is the first
one on adaptive management and monitoring. Humans have exploited the Bering Sea ecosystem
for hundreds of years, at least, but because of environmental variability and the lack of adaptive
(experimental) approaches to management, our understanding of the system remains meager.
This problem is not unique to the Bering Sea; it is common to many if not all problems of
natural resource management (see, for example, NRC, 1996 for a discussion of this problem
with respect to salmon in the Pacific Northwest.)
· An adaptive or experimental approach should be taken to all management actions
concerning the Bering Sea ecosystem. Despite the committee's conclusions that the cascade
hypothesis is a plausible explanation for at least some of the changes observed in the Bering Sea
over the past 50 years and that the only significant human activity that could have affected the
Bering Sea ecosystem is fishing, much remains unknown about the ecosystem and its
functioning. Regulated human activities such as fishing provide some of the best possible
vehicles for experimentation and improving understanding, as do protective activities mandated
by the Endangered Species Act and the Marine Mammal Protection Act. It is therefore of
critical importance that such activities and related regulations be designed such that information
can be gained from them wherever possible. In addition to information already required, such
as catch statistics, regulations should be implemented on an adaptive basis wherever possible.
For example, no-fishing zones have been established adjacent to 43 sea lion rookeries, but some
people, including members of this committee, believe that they are too small. Therefore, the
National Marine Fisheries Service should reexamine the size of the no-fishing zones based on
actual foraging ranges and habits of juveniles. In particular, no-fishing zones of various sizes
should be implemented in a controlled way. As another example, the committee suggests that
experimental fishing (and perhaps even overfishing in some carefully selected and limited areas)
would be of value. Thus, in a few selected areas, one might set catch limits on pollock and
some Catfish species above the level estimated to be sustainable, with carefully designed
experimental monitoring of a variety of ecological factors, including those mentioned in the
- recommendations that follow.
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256
Research to hnprove Understanding of the Ecosystem
The Bering Sea Ecosystem
Two of the most important questions about the functioning of the Bering Sea ecosystem
concern pollock, which appears to be an important (keystone) species in the ecosystem (Bakkala,
1993; chapters 4 and 6), and the effects of sea ice, which has a major influence on the
oceanography of the eastern Bering Sea shelf (Coachman, 1986; Ohtani and Azumaya, 1994;
Chapter 3), and hence on the life of bottom-dwelling and nearshore species such as crabs,
Catfishes, and herring. Research on the more general questions about the ecosystem should keep
these two questions in mind. The committee recommends research on the following questions.
· What are the nature and causes of the dynamics of pollock in the northeastern Pacific
and Bering Sea over the past 50 years? Understanding this broad question can be approached
by asking a number of more specific questions:
a. Is the cascade hypothesis a plausible scenario for ecosystem dynamics? To answer
this question, models would be useful. Is it possible to model energetics and energy transfers
to arrive at a result that is consistent with the cascade hypothesis, with experience in other
ecosystems, and with the available data? What is the effect of releasing zooplankton from
predation? To what degree are alternative states of ecosystem organization stable? How likely
is the organization to return to its previous state or to some other state?
b. What are the short- and long-term effects of commercial fishing on the structure and
dynamics of the Bering Sea ecosystem? Short-term effects might be investigated through
adaptive management of the fishery, as described in the first research recommendation. Longer-
term effects could be investigated through modeling and through comparisons with other large
ecosystems, in addition to the continued, controlled collection of relevant data about fishing and
its effects. Important questions include the effects of removing commercial species on their
predators, their competitors, and their prey. In each case, information about substitutability is
unportant, e.g., would their predators switch to other food sources and would their prey be eaten
by their competitors? How does fishing affect the distributions of various species? How wide-
ranging are its effects, e.g., how does fishing off Attu Island affect distributions and abundances
of species in Norton Sound?
- c. What are the roles of top-down and bottom-up forcing in the Bering Sea ecosystem?
Do commercial, subsistence' and recreational fishery effects tend to be top-down and
environmental effects bottom-up? How do such effects manifest themselves?
d. What are the relationships between juvenile pollock and other forage species (e.g.,
capelin and Pacific sand lance) in the ecosystem? How do they organize the time and space
dynamics of the top-level predators such as birds and marine mammals (and human fishers)?
Answering this question would require studies of at-sea ecology of marine mammals and birds.
More information is needed on the foraging locations and diets of marine mammals, especially
pinnipeds. Long-term information on the distribution and abundance of seabirds at sea would
be valuable to help understand foraging patterns and their relationships to oceanic productivity
and the distribution and abundance of plankton and small fish. Finally, focused time series
studies of the geographic and spatial distributions (and variability) of macrozooplankton are
needed. This information is needed to study and understand the behavior of larger invertebrates,
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257
and the vertebrates (including pollock) that rely on them and on zooplankton as a significant part
of their diet.
· What is the role of ice in structuring the Bering Sea ecosystem? This general question
encompasses many questions about the eastern Bering Sea shelf resources, in particular those
concerning crabs, Catfishes, and herring, and their population dynamics. They are all influenced
by bottom temperatures, which in turn are influenced by sea ice. More specific questions
include the following:
a. What are the habitat requirements of various commercial invertebrates (especially crab
species) and demersal finfishes (especially Catfishes and herring)? It would be valuable to know
the habitat preferences and requirements (if any) of these species, and the relationship of fishing
activities to their occupation of various habitats. A habitat and distribution atlas would be
helpful.
b. How did the seasonal and interannual dynamics of ice affect the collapse of the
eastern Bering Sea king crab fishery? Would it have been possible to manage the fishery so as
to avoid the collapse?
· What are the periodicities of ecosystem changes? Much of this information can be
obtained by analysis of existing data and by extrapolation from other related systems, but most
will require long-term study. In some cases, the information is already being collected, and
financial and administrative support is needed for continued study. Information is needed on the
periods of physical changes such as the position of the Aleutian Low, ocean circulation changes,
and sea surface temperatures. Better and longer-term information is needed on the distribution
and abundance of marine mammals, seabirds, fish, benthic invertebrates, and plankton.
· How do lower trophic levels of the ecosystem interact? Better understanding of the lower
levels of food webs is needed, especially trophic roles and dynamics. Planktivorous birds (and
fishes, if their place and time of collection are carefully documented) can be used to monitor at
least the surface distribution and abundance of various planktonic species.
· What are the structure and functioning of the "green belt?" It is important to understand
the green belt better, to know the degree to which it supports productivity of various parts of
the Bering Sea ecosystem, and to know more about the physical and biological features that
make it more productive than other parts of the Bering Sea. Does it serve as an important
source of biological production for the eastern, central, and western Bering Sea? Does it
provide a connection between those areas; i.e., do changes in the green belt affect the various
areas in a related way?
· How well are the management and institutions of the Bering Sea structured to address
problems and provide appropriate management solutions? The committee recommends
detailed study of these institutions (for the reasons described in more detail in Chapter 7); the
important questions to ask about each institution would include:
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The Bering Sea Ecosystem
· the geographic area under its purview;
· the resources and activities under its purview;
· the basis for its authority;
· the legislative mandate or other operational objectives
· its basic operational procedures;
· its source and level of funding; and
· any implicit or explicit links between it and other organizations in research, planning,
~ ,
or operations.
This information would help to develop understanding of the areas and types of regulation.
Answers to these questions could help answer other questions, such as whether the North Pacific
Fishery Management Council should be given more or less centralized authority or whether it
should be restructured, and whether the Magnuson Fishery Conservation and Management Act,
the Marine Mammal Protection Act, and the Endangered Species Act are compatible with a
program of research and management with an ecosystem perspective.
Management and Institutional Recommendations
Institutions
The committee identified four basic problems that need to be solved to achieve proper
management of the Bering Sea ecosystem: the lack of knowledge and inherent limitations on
understanding and predictability, incomplete specification of management objectives, lack of
appropriate domestic institutional structures through which to make and implement coordinated
management decisions on either side of the Bering Sea, and the Innited ability to coordinate
domestic management with users and management agencies of other nations. The committee
recommends the following steps to address these problems (described in detail in Chapter 71:
· Improve the coordination of the complete web of institutional structures that
make management decisions concerning resource use in the Bering Sea.
· Coordinate the philosophy and objectives of laws dealing with management in the
Bering Sea ecosystem.
· Improve processes and institutions to coordinate the implementation of major
federal acts relating to resource use in the ecosystem, and federal-state and international
management.
~ Develop a research program to increase understanding of the Bering Sea
ecosystem (keeping international issues and cooperation in mind), to fulfill the research
needs identified by the committee to help future policy makers solve both short-term
management and longer-term ecological problems.
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Gaps In Knowledge and Recommendations
Specific Action to Reverse Declines in Marine Manunals and Birds
259
To reverse declines in marine mammals and birds, broaden the distribution of fishing
effort in space and time, especially for pollock. As described in Chapter 6, there is a significant
likelihood that concentrated fishing for pollock in some places at some times can have an adverse
effect on availability of food for marine mammals and birds, especially juveniles. Therefore,
fishing over wider areas and over longer periods is likely to improve the food supply for these
animals, and is extremely unlikely to have adverse effects. The intent of this recommendation
is not to increase total catches, and some areas should probably still be closed to fishing for
conservation of fish, bird, and mammal populations. As with all management actions, if this
one is adopted, it should be done on an adaptive basis.
TO FUTILE
The Bering Sea ecosystem, like all ecosystems, has been affected by natural fluctuations
since time immemorial. Like most ecosystems, it has been affected by human activities since
prehistory, but especially within the past 200 years as commercial exploitation developed. Thus,
the recent changes that we see today should not be thought of as perturbations of a "pristine"
ecosystem, but as part of a pattern of change affected by a complex array of natural and human
influences.
The complexity of the influences on the ecosystem makes understanding and management
difficult, but some things are clear. First, environmental change will continue to occur in the
future. Second, significant human exploitation of a single species can affect not only that species
but many other species as well. In other words, there are connections among ecosystem
components. Finally, the total productivity of the ecosystem has a limit, which means that
human use of living resources will affect the ecosystem to some degree. Those three
conclusions imply that unexpected events will continue in the future and that they will be larger
as living resources are more heavily exploited. It also follows that actions with respect to single
species will have complex consequences that will be hard to predict. Simply changing
exploitation rates on a single species-pollock, for example-is unlikely to have easily
predictable effects on other ecosystem components-marine mammals, for example.
To operate successfully within this complex system, management strategies must be based
on long-term data on physical and biological phenomena and must be adapted as we learn more
about the structure and functioning of the ecosystem. A better understanding of institutional and
socioeconomic factors will also be needed. Finding a balance between human uses of the
region's many resources and maintaining other desired aspects of the ecosystem, such as high
productivity of marine mammals or a particular composition of fish communities, will be an
ongoing challenge.
Representative terms from entire chapter:
sea ecosystem
