The issue
The ocean varies naturally The
primary source of food from the oceans is from
capture fisheries (including gleaning and
recreational fisheries) and aquaculture. The
biological productivity which fisheries exploit
varies from place to place and over time in
relation to oceanographic conditions which change
naturally, from year to year and seasonally. Some
natural fluctuations are less frequent, changing
only after decades. In addition, the oceanic
environment is affected by long-term global climate
change caused by both natural processes and human
impacts, such as the emission of greenhouse gasses.
Any effects of such climate change on fisheries
will occur in a sector already characterized on a
global scale by full utilization, massive
over-capacities of usage and sharp conflicts
between fleets and among competing uses of marine
ecosystems. Climate-change impacts are likely to
exacerbate existing stresses on marine fish stocks,
notably fishing pressure, diminishing wetlands and
nursery areas, pollution, and UV-B radiation. The
effectiveness of actions to sustain fisheries
depends on our capacity to distinguish among these
stresses and other causes of change. This capacity
is insufficient and, although the effects of
environmental variability are increasingly
recognized, the contribution of climate change to
such variability is not yet clear.
Natural variation obscures global change and
both affect fisheries development and management
outcomes. An overarching concern is that society
will not recognize the effects of climate change
because the natural variability of the marine
environment and fisheries production is so great.
Only in the last few years has it become clear that
there are climate patterns of a decadal scale that
affect production on an ocean basin scale, perhaps
even globally for some species. Will global climate
affect the frequency of these natural oscillations
or change their magnitude? Presently there is no
answer. However, society has the opportunity to
monitor environmental changes and learn about their
effects, so that better production forecasts can be
made for fisheries managers.
Potential effects Scenarios
developed by the Intergovernmental Panel on
Climate Change (IPCC) forecast - with
indications of "confidence" levels - the following
effects:
- Globally, saltwater fisheries production is
hypothesized to be about the same, or
significantly higher, if resource management
deficiencies are corrected. Also, globally,
freshwater fisheries and aquaculture at
mid-to-higher latitudes could benefit from
climate change. Medium Confidence
- Local shifts in production centres and mixes
of species in marine and fresh waters are
expected as ecosystems are displaced
geographically and changed internally. High
Confidence
- Positive effects such as longer growing
seasons, lower natural winter mortality and
faster growth rates in higher latitudes may be
offset by negative factors such as a changing
climate that alters established reproductive
patterns, migration routes, and ecosystem
relationships. High Confidence
- Changes in abundance are likely to be more
pronounced near major ecosystem boundaries. The
rate of climate change may prove a major
determinant of the abundance and distribution of
new populations. Rapid change due to physical
forcing will usually favour production of
smaller, low-priced, opportunistic species that
discharge large numbers of eggs over long
periods. High Confidence
- There are no compelling data to suggest a
confluence of climate-change impacts that would
affect global production in either
direction.
- Marine stocks that reproduce in freshwater
(e.g. salmon) or require reduced estuarine
salinity will be affected by changes in
temperatures and the amount and timing of
precipitation and on species tolerances. High
Confidence
- Where ecosystem dominances are changing,
economic values can be expected to fall until
long-term stability (i.e. at about present
amounts of variability) is reached. Medium
Confidence
- Subsistence and other small-scale fishers
who lack mobility and alternatives, and are
often the most dependent on specific fisheries,
will suffer disproportionately from changes.
Medium Confidence
- Because natural variability is so greatly
relative to global change, and the time horizon
on capital replacement (e.g. ships and plants)
is so short, impacts on fisheries can be easily
overstated, and there will likely be relatively
small economic and food supply consequences so
long as no major fish stocks collapse. Medium
Confidence
- The sensitivity to global change will vary
between fisheries. The most affected will be
fisheries in small rivers and lakes, in regions
with larger temperature and precipitation change
and on anadromous species. They will be followed
by fisheries within Exclusive Economic Zones,
particularly where rigid access-regulations
reduce the mobility of fishers and their
capacity to adjust to fluctuations in stock
distribution and abundance; fisheries in large
rivers and lakes; fisheries in estuaries,
particularly where there are species without
migration or spawn dispersal; and in the high
seas.
More specifically for fisheries, climate
change-related warming may result in:
- longer growing seasons and increased rates
of biological processes - and often of
production.
- greater risk of oxygen depletion.
- species shift to more tolerant of warmer and
perhaps less-oxygenated waters.
- redeployment or re-design and relocation of
coastal facilities;
- coastal cultures may need to consider the
impacts of sea-level rise on facilities and the
freeing of contaminants from nearby waste
sites;
- changes in precipitation, freshwater flows,
and lake levels. Strong regional variations are
likely.
- introduction of new disease organisms or
exotic or undesired species;
- establishment of compensating mechanisms or
intervention strategies;
- a longer season for production and
maintenance;
- modification of aquaculture systems, e.g.
keeping them indoors under controlled light, may
be needed more often to protect larvae from
solar UV-B. In addition, several of the above
and other factors, such as competing demand for
coastal areas, may argue for technological
intensification in ponds and non-coastal
facilities.
Possible solutions
While the fisheries sector cannot do much to
impede or seriously affect global climate change,
it could contribute to its stabilization or
reduction, and to mitigating its effects. Climate
changes notwithstanding, there are several actions
to consider. The most important strategies are
those needed to promote sustainability and which
are useful and practical, even in the absence of
climate change. Further, when developing
strategies, we need to consider both the problems
and the opportunities that are being presented, in
the following way:
- active participation at global and regional
level, to ongoing debate and collaboration, to
obtain the best possible information of
fisheries-related impacts;
- allocating research funds to analyze local
and regional potential changes in resource
magnitude and composition and likely
socio-economic impacts;
- sharing information obtained with the sector
on potential changes, their scale and possible
effects on resources and fisheries;
- establishing institutional mechanisms to
enable or enhance the capacity of fishing
interests (fleets and other infrastructures) to
move within and across national boundaries as a
consequence of changes in resources
distribution. This implies developing bilateral
agreements.
- preparing contingency plans for segments of
the sector that might not be able to move,
particularly for disadvantaged areas and
small-scale fishers lacking mobility and
alternatives.
- developing effective national and
international scale resource management regimes
and associated monitoring systems to facilitate
adaptation of exploitation regimes in a shifting
environment;
- strengthening regional fisheries management
organisation and other mechanisms to deal with
cross-border stocks;
- integrating fisheries management into
coastal areas management to ensure that
fisheries needs are taken up when dealing with
protection of coastal areas from sea level rise,
etc. For instance, to ensure that public works
to protect coastal areas do not unnecessarily
obliterate nursery areas important to
fisheries;
- analyzing aquaculture sustainability in an
eco-regional context, forecasting changes in
productivity or resistance and in required
related changes in culture systems, cultured
species or delocalisation of productive systems.
Particular attention should be given to coastal
investments.
- fostering interdisciplinary research, with
scientists meeting periodically to exchange
information on observations and research
results, and meeting with managers to ensure the
proper interpretation of results and the
relevance of research.
- foreseeing and planning infrastructure
adaptations. It could be expected that, in
response to shifting populations and species,
the industry will respond with faster,
longer-range fishing craft, install on-board
processing equipment to replace endangered
coastal ones or use floating processors when
feasible, and find alternative means of
transport when coastal roads are flooded and
relocation is not possible. Governments should
also consider constructing and maintaining
appropriate infrastructure for storm
forecasting, signalling systems and safe refuges
for dealing with possible rising sea level and
increased storminess. There may be opportunities
to take advantage of reduced need for ice
strengthening of vessels and infrastructures in
a warmer climate, except perhaps for areas with
increased icebergs.
Action taken
The international activity already related to
climate change is very intense as can be seen
looking at the various Web sites dealing with it.
Most of the action refers, however to research and
international agreements. Research focuses on
tracking indicators of change, studying
cause-effect relationships, modelling, assessing
and forecasting impacts. International agreement
such as the UN Framework Convention on Climate
Change aim at mobilising attention and
commitments of governments to reduce greenhouse
gases. Little or no action has been taken by
governments to mitigate the possible effects, and
information on contingency plans is lacking.
In fisheries, while climate change has been
addressed occasionally in scientific literature,the
subject has not yet been formally addressed by most
industry or fishery management administrations.
However, the fishery sector and fisheries research
are fairly advanced in this matter, through their
dealing with the El Niño, decadal changes in
ocean environments and other longer terms
fluctuations in fisheries environments and
resources. The observation programmes, scientific
analyses, computer models, the experience gained
and strategies developed by fishers, processors,
fishfarmers, and management authorities confronted
with the problem of medium-to-long-term natural
fluctuations, is extremely useful for dealing with
climate change. Many of the principles and
strategies developed to deal with "unstable" stocks
will be of use when having to deal with climate
change.
The Global Ocean Observing System (GOOS)
has been established under the aegis of
IOC-UNESCO.
Outlook
Changes remain uncertain and competing theories
are still developing as to the reality of the
change, its magnitude and its mechanisms. Progress
in implementing the UN Framework Convention on
Climate Change is slow and resistance from some of
the major players to pledge reduction of gas
emissions remains a stumbling block. It is not
possible to forecast how the question will
evolve.
Fisheries will be able to move faster towards
specific assessments and contingency plans when
more precise and reliable predictions are available
on projected climate change with at least a
regional resolution. An example of a regional
analysis showing potential impacts of climate
change (along the East Coast of the USA) is listed
in "additional reading". In the meantime, dealing
effectively with medium-term natural changes offers
a good "training field".
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