Download Impact of climate change on fisheries and fishing communities

Impact of climate change on fisheries and fishing communities
Climate change (global warming) is leading to changes in the basic
biophysical processes that determine the structure and function of the oceans
and other aquatic ecosystems, and it is these ecosystems that sustain capture
fisheries and provide the environments in which fish are farmed. As recently
reviewed by the Intergovernmental Panel on Climate Change (IPCC, 2007),
climate change in the oceans and freshwaters leads to changes in physical
processes such as: alternations in the major ocean currents and in the local
circulation patterns in coastal systems; thermal expansion and addition of icemelt to the oceans, leading to sea level rise.
In freshwater, rainfall and river-flow patterns and rates of evapo-transpiration
are changing. Storms, floods and droughts are changing in frequency and
intensity. Chemical changes brought about by warming are also leading to an
acidification of the oceans, with consequences for ocean food chains and the
formation of coral reefs. The links between warming, these physical changes
in hydrology and oceanography, the ecological changes in aquatic food webs,
and the operation and economics of the fishing sector are thus complex.
We structure this review around a simplified schema that illustrates some the
main potential pathways of impact from physical and chemical changes to fish
and ecosystems. These impacts on production and distribution of fish and on
the structure and function of oceanic and aquatic ecosystems and food webs
then interact with effects of increased storminess, floods, droughts and sealevel rise, and with a variety of indirect effects (including adaptation in other
sectors), to have impacts on fisheries at household or operational level,
community and sectoral level, and on national economies in countries where
fisheries are significant.
Many of the potential pathways of impact linking global warming, through
physical and chemical change of oceans and fresh waters, to effects on
aquatic ecosystems, have been identified in the scientific literature. Some of
these pathways have been modelled and their effects quantified but it is still
not possible to make predictions about the combined effects of all of these
changes, and how they may reinforce or counter-act each other. It is thus
impossible to make confident science-based forecasts about the future
composition, distribution and productivity of exploited fish species. What one
can do, in some but not all cases, is to identify which pathways are likely to
have special relevance to different kinds of fishery system (inshore, coastal,
reef-based, oceanic) and infer the direction of change that can be expected in
the fish resources within the waters of the countries studied and the means of
production.
Climate change implications for fisheries
We consider the impacts of climate change on fisheries and aquaculture as
social and economic systems. Thus, we elaborate on the fishery and
aquaculture impacts that result from changing production and distribution of
fish populations and the ecosystems that support them, and we also consider
the physical impacts climate change, has directly on fishing operations and
fishing communities, independently of impacts on fish and ecosystems (e.g.
sea level rise and increased storm severity affecting fishing and fish-farming
people‘s homes and fishing and aquaculture infrastructure). We also highlight
some of the many and complex potential indirect effects of climate change on
fisheries (e.g. increased investment in water storage and irrigated agriculture,
leading to impacts on river and reservoir fisheries; emissions reduction
policies leading to reduced subsidies on aviation fuel, in turn leading to
increased costs of air-freighted fresh fish exports). We consider impacts at
two main levels, which correspond approximately to the domains of microand macro-economic analysis:
Within the sector – impacts on incomes, assets, livelihoods of individual
fishers, processors, fish farmers and communities; and
Sector contribution to national economies – impacts on revenues, exports,
per capita fish supply, contribution to employment and GDP at national levels.
The potential impacts on these two levels will vary by region/location, and
differing levels of adaptive capacity of individuals, communities, fleets and
economies and societies. In general terms, macro-economic concerns arise
only when fisheries are sufficiently prominent in society and the economy to
be a concern for national economic planning. This will be the case for many
small developing Commonwealth States, particularly many island states,
where fisheries number among the major export revenue sources. Within the
sector, the impacts of climate change will be experienced by all, regardless of
the relative importance of the sector in the wider economy, and investment in
adaptation that is commensurate with the size of the sector will be required.
Climate-related impacts will also be affected by other non-climate related
stresses and opportunities. In capture fisheries, the principal additional stress
is heavy pressure from poorly regulated fishing activity; in aquaculture, it is
competing uses for coastal, land and water resources.
Climate change implications for fishers, communities, fleets and
national economies
Within-sector impacts: Direct and indirect impacts of changes in production
volumes and species mix and of changes in aquatic environmental conditions
Changes in total catch, the composition of the catch, and the distribution of
fish will have impacts on costs and earnings of fisherfolk. While some areas
may experience an increase in fish production – as has been suggested for
the Arabian Sea. Many areas will see reductions in production associated with
reduced primary productivity and, for near-shore tropical fisheries, habitat
damage from coral bleaching, as well as other stresses on the coastal
environment.
Changes in fishing methods used; for example from targeting small pelagic
fish with seines to diving for shellfish, or from line-fishing to pot and trapfishing, as different species become more or less available.
Changes in aquaculture production systems: This could include the use of
warmer-water adapted species, or species able to grow on a diet low in fishderived feed - itself in short supply due to excess demand and impacts of
climate change on small-pelagic stocks used for fish oil and fish meal. There
could also be changes in production systems, for example in coastal areas,
there may be a greater inland penetration of brackish-water aquaculture, such
as shrimp farming, as low-lying coastal land gets flooded by salt water more
often and loses its value as rice-growing land. Increased frequency of toxic
algal blooms associated with both temperature rise and increased nutrient
levels could close off shellfish fisheries, such as those for scallops, oysters
and mussels.
Changes to marketing chains: Many species of fish currently traded in
higher-value international markets by Commonwealth States and other
developing countries are both suffering intense exploitation and are sensitive
to climate change. These include the fish traded in the live reef-fish trade to
Asia, and the global trade in tuna species. Domestic urban and export
markets that are supplied from aquaculture dependent on the collection from
the wild of climate-sensitive natural larvae, spat or seed could begin to
disappear in their current locations. These may include oysters, mussels,
some shrimp and crab species, spiny lobsters and some groupers and, in
freshwaters, some of the Indian major carps. An obvious adaptive measure is
to close the life-cycle of these species by developing hatcheries, but this can
be both technologically demanding, expensive, and lead to loss of an
important source of livelihood for the poor. In coastal Bangladesh, for
example, hundreds of thousands of people make a seasonal living by
collecting shrimp post-larvae for the country‘s export-orientated shrimp
farming sector.
Shifts in the balance between fishing, aquaculture and other livelihood
activities:
If fishing becomes less profitable or predictable, fisherfolk will invest more in
seeking alternative occupations. Although some disinvestment will be
beneficial where there is over-capacity and over-reliance on fisheries,
diversification can also imply less investment in efficient technology and a
consequent reduction in comparative advantage. Alternatively, with agriculture
also impacted by climate change and increasing drought-induced crop failure
in some areas (e.g. Southern Africa, Sahel fringe), more people could come
into fishing as a safety net‘ occupation, further threatening over-exploited fish
stocks and reducing resource rents and sectoral efficiency and
competitiveness in export markets. In aquaculture, problems with disease
management and a lack of stable and equitable access to input and output
markets mean that it can be a high risk venture. Further climate-associated
risks could slow the growth of aquaculture and lead to further capital
intensification, reducing recent gains in closing the supply gap‘ through
provision of lower-cost food to lower-income fish consumers, and providing
millions of small-holder farmers in developing countries with a new cash-crop
and nutritious supplement to staple crops.
Direct and indirect impacts of increased storm severity and sea level
rise:
There are on-going scientific controversies around the general perception that
storm frequency and severity are increasing due to climate change, and that
there may be changes in seasonality and typical track of storm events. An
emerging consensus around recent trends and predictions for hurricane
energy (a measure of storm severity) indicate no evidence for increased
frequency of storms, but strong evidence for a trend of increasing severity and
therefore destructiveness of storms over the last 20-40 years (i.e. exceeding
the periodicity of decadal cycles in the ocean climate system and attributable
to anthropogenic warming); this trend is particularly evident in the western
Atlantic.
Vulnerability and resilience of the fisheries sector to climate change
impacts
A recent study on the vulnerability of national economies and food systems to
climate impacts on fisheries has revealed that African countries are the most
vulnerable to the likely impacts of climate change on fisheries. This is in spite
of over 80 percent of the world‘s fishers being in South and Southeast Asia,
and fish catches being greater in Latin America and Asia. What makes African
fisheries so vulnerable? The analysis suggests that semi-arid countries with
significant coastal or inland fisheries have high exposure to future increases in
temperature (and linked changes in precipitation, hydrology and coastal
current systems), high catches, exports and high nutritional dependence on
fish for protein, and low capacity to adapt to change due to their comparatively
small or weak economies and low human development indices. These
countries include Angola, Congo, Mauritania, Mali, Sierra Leone, Senegal and
Niger.
Fisheries provide employment for up to ten million people in Africa and
provide a vital source of protein to 200 million people. Protein may be
particularly limited in these countries resulting in high dependency on wild
caught fish and bush-meat. Other vulnerable nations include Rift valley
countries such as Malawi, Uganda and Mozambique and Asian riverdependent fishery nations including Pakistan, Bangladesh and Cambodia.
Countries such as Russia, Peru and Columbia are sensitive to climate
changes due to their high catches and reliance on exports or high
employment from fisheries, but their larger economies and higher human
development indices mean they are likely to have a higher adaptive capacity
to deal with potential impacts.
Biophysical &
Environments
Ecological
Changes
to
Marine
&
Freshwater
Climate change is having a significant impact on the United Kingdom’s marine
environment according to a new report. The Marine Climate Change Impacts
Partnership report card 2007-08 highlights just how much climate change has
affected the UK’s marine environment and what the future impacts may be:
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2006 was the second warmest year for UK coastal waters since
records began in 1870; seven of the 10 warmest years have been in
the last decade.
Warmer winters have been strongly linked to reduced breeding
success and survival in some seabird populations.
Models predict fewer storms in future but there will be increased
numbers of severe storms.
Coastal erosion and flooding is expected to increase.
Marine climate change is having a significant impact on the marine
environment and the goods and services it provides.
Coastal erosion is occurring along 17 per cent of the UK coastline (30
per cent of England’s coastline; 23 per cent of Wales; 20 per cent of
Northern Ireland; 12 per cent Scotland).
Recent warmer conditions and associated shifts in the abundance and
geographical distribution of plankton have led to reduced availability of
prey fish for some seabirds, which has been strongly linked to recent
poor breeding success and reduced survival rates.
The impacts of climate change on the commercial services provided by
our seas will be significant. Sea-level rise, coastal flooding, storms and
bigger waves will affect ports, shipping and built structures. Fishing and
fish farming will be affected by temperature change and plankton (prey)
availability.
Coastal regions, areas that are home to a large and growing proportion of the
world's population, are undergoing environmental decline. The problem is
particularly acute in developing countries. The reasons for environmental
decline are complex, but population factors play a significant role. Today,
approximately 3 billion people, about half of the world's population live within
200 kilometres of a coastline. By 2025, this figure is likely to be double. The
high concentration of people in coastal regions has produced many economic
benefits, including improved transportation links, industrial and urban
development, revenue from tourism, and food production. But the combined
effects of booming population growth and economic and technological
development are threatening the ecosystems that provide these economic
benefits. Unless governments and users of coastal resources take action,
population pressures and the associated levels of economic activity will
further degrade many coastal habitats.
The challenge for policymakers and coastal resource managers is to figure
out how to reap the economic benefits of coastal resources while preserving
them for future generations. Addressing population issues is key to achieving
such balance. This policy brief looks at how population growth, urbanization,
and other factors affect coastal resources; how environmental degradation
influences people's lives; and how policymakers can integrate population and
resource management issues.
The socio-economic context of fisheries, or a direct threat to coastal
populations
Coastal Regions: Benefits and Challenges
There is no common definition of what constitutes a coastal region. Most are
based on an area within 60 to 200 kilometres of the shoreline and may include
coastal floodplains, coastal forests called mangroves, marshes, and tideflats
(coastal areas affected by the rise and fall of the tide), as well as beaches,
dunes, and coral reefs. The term "coastal regions" also covers marine
fisheries because the bulk of the world's marine fish harvest is caught or
reared in coastal waters. Coastal areas help prevent erosion; filter pollutants;
and provide food, shelter, breeding areas, and nursery grounds for a wide
variety of organisms. Coastal regions also provide critical inputs for industry,
including water and space for shipping and ports; opportunities for
recreational activities such as fishing and diving; and other raw materials,
including salt and sand.
In many countries, populations in coastal areas are growing faster than those
in non-coastal areas. This is a concern because population growth and the
activities associated with it can degrade coastal and marine ecosystems. A
number of worrying trends are already visible. In some areas, heavy use of
fisheries has reduced endemic coastal fish stocks to 10 percent to 30 percent
of the supply that existed 30 years ago. Half of the world's wetlands
disappeared in the 20th century, as did 50 percent of all mangroves, and
nearly 60 percent of the world's coral reefs are seriously degraded, in some
cases beyond recovery or threatened by development and other human
activities. Pollution from industry, agriculture, and urban areas is degrading
the quality of much of the world's fresh water. These challenges are
particularly acute for island countries, where coasts often comprise the entire
territory. Such countries may also be threatened by rising sea levels, a
possible consequence of climate change.
Population Factors Effects on Coastal Regions
Changes in the size, composition, and distribution of human populations affect
coastal regions by changing land use and land cover. Fishing or harvesting,
the destruction of mangroves, and pollution and sedimentation from human
activities all can affect the coastal environment.
Population Density
The average population density in coastal areas is about 80 persons per
square kilometre, twice the world's average population density. Up to 50
percent of the population in northern Africa and Bangladesh lives in coastal
areas; along the Nile Delta, the population density reaches 500 to 1,000
people per square kilometre. The additional demands that high population
density places on the coasts have meant that higher density is associated
with increased risks to marine ecosystems. But higher population densities
may have beneficial effects as well: As population grows, some governments
make greater investments in infrastructure such as sewer lines and sewage
treatment plants that ultimately reduce levels of environmental contamination.
Migration
Migration is a key factor affecting coastal zones. The figures in China and
Southeast Asia are staggering: 1,000 people arrive in China's large coastal
cities each day, and similar numbers move to the coasts in Vietnam and the
Philippines. The population of Ecuador's Galapagos Islands has grown rapidly
since the early 1980s, largely due to the arrival of coastal fishermen. These
fishermen sometimes unknowingly exacerbate a problem created by tankers
and ocean liners. By discharging ballast water near the islands, large vessels
and smaller fishing boats have introduced non-indigenous plant and animal
species to the islands' coasts. The situation in the Galapagos Islands also
highlights how migration can contribute to the depletion of natural resources.
The arrival of new fishermen, together with the introduction of new fishing
techniques and increased access to credit and markets, has contributed to the
overexploitation of sea cucumbers in the region.
Urbanization
Many of the world's coasts are becoming increasingly urban. In fact, 14 of the
world's 17 largest cities are located along coasts. Eleven of these cities,
including Bangkok, Jakarta, and Shanghai, are in Asia. In addition, two-fifths
of cities with populations of 1 million to 10 million people are located near
coastlines. The urbanization of coasts brings with it coastal development
(including demands for fresh water and sewage treatment) and damage to
coastal ecosystems.
Urbanization has a deleterious effect on mangroves. Mangroves, forests of
salt-tolerant trees and shrubs that grow in the shallow tidal waters of estuaries
and coastal areas in tropical regions, about 8 percent of the world's coastlines
and 25 percent of the world's tropical coastlines, where they absorb the
impact of storms and offer nutrients for most of the world's marine life. A study
by the U.S-based World Resources Institute found that mangrove loss was
strongly correlated with the growth of cities and ports. Mangrove forests are
also cleared for timber and to make room for fish and shrimp ponds, human
settlements, and agricultural and industrial development. Kenya, Liberia, the
Philippines, and Puerto Rico, have lost over 70 percent of their mangroves.
Population's Interaction with Other Factors
Non-demographic factors, including the economy, national and local policies,
technology, and culture, interact with population changes to affect the natural
environment. Tourism, fishing, and aquaculture are industries with major
economic influences on coastal ecosystems.
Tourism
Coastal areas worldwide are major destinations for tourism, which represents
the fastest growing sector of the global economy. Tourism dominates the
economy of some regions and small island states; for example, tourism
constitutes 95 percent of the economy of the Maldives and is the country's
only source of hard currency. Tourism can offer some environmental benefits,
such as greater appreciation of the value of natural resources. In the
Caribbean, for instance, diving tourism has helped raise awareness about the
need for reef conservation. But tourism can also have harmful effects such as
it can lead to unsustainable coastal development as infrastructure is built on
the shoreline to accommodate tourists. In the Caribbean, official estimates
say that 70,000 tons of waste is generated annually from tourism activities.
Yachts, charter boats, and cruise ships are major sources; they bring visitors
to ports that often have inadequate collection systems for dealing with the
solid waste discharged by the ships. Moreover, the ships provide few longterm economic benefits for the local population, since they do not employ
many local citizens.
Fishing and Aquaculture
Marine fisheries and aquaculture (the controlled cultivation and harvesting of
freshwater and marine organisms) produce close to 100 million tons of fish,
shellfish, and edible plants every year, providing a livelihood for about 35
million people, most of whom live in developing countries. Over-harvesting to
meet global consumers' growing demand for seafood can deplete many
species and alter the biological structure of coastal ecosystems. Many
species are over-harvested because the world fishing fleet is larger than it
needs to be. Other problems include destructive harvesting methods such as
trawling (dragging weighted nets across the sea floor to catch shrimp and
bottom-dwelling fish), and by-catch (unintended catch of non-target species).
Modern trawling equipment scoops through sediment and rock and often kills
the worms, sponges, and other species that live on the seafloor. Aquaculture,
the world's fastest growing food production activity, with an annual growth rate
of about 10 percent in the 1990s, can lead to the destruction of mangroves
and may lead to irreversible damage to both estuarine and offshore fisheries
by introducing biological, chemical, and organic pollutants (such as antibiotics
and pesticides) and by modifying habitats.
Human Health, Food Security, and Gender Issues
People who live in coastal regions may suffer the cumulative burden of
environmental stress from the activities and overcrowding of the coast and
from upstream and inland development. If not properly managed,
development can result in pollution, deforestation, and inadequate
management of soil, water, pesticides, and fertilizers. Damming rivers can
also have negative environmental effects, such as soil erosion and destruction
of ecosystems that support various fish and marine mammals. When
concentrated in small, confined, and overcrowded areas such as coastal
zones, pollution and other problems pose greater threats to human health.
Worldwide, sewage is the largest source of environmental contamination, and
discharges have increased dramatically in the past three decades. Eighty
percent of marine pollution comes from land-based sources; the remaining 20
percent comes from atmospheric sources, including acid rain and marinebased sources such as oil spills. As coastal communities grow, sewage can
become a threat to local waterways: Demand often exceeds available sewage
treatment, and much of the sewage is dumped without being treated. Bathing
in or ingesting sewage-contaminated water can cause infections and transmit
diseases such as cholera, particularly among children under 5.
In developing countries, more than 90 percent of wastewater and 70 percent
of industrial wastes are discharged in coastal waters without being treated.
The United Nations Environment Programme estimates that South Asian
waters are at the highest risk of pollution: 825 million people in the region do
not have basic sanitation services. In Mumbai, India, for instance, almost half
of the city's 12 million residents are either slum dwellers or homeless with little
access to sewage and sanitation facilities. The Municipal Corporation of
Brihan Mumbai, with support from the World Bank, has started the $300
million Bombay Sewage Disposal Project to collect and dispose of 80 percent
of the sewage currently flowing untreated into the sea.
Chemicals and heavy metals found in pesticide runoff and industrial effluents
also damage human and marine health. The most serious concerns
worldwide involve persistent organic pollutants (POPs), which can be
transported in the atmosphere and have become common in the oceans.
POPs tend to linger in living tissue and become more concentrated as they
move up the food chain, so they are sometimes found even in people who live
in remote, undeveloped regions. Evidence links long-term, low-level exposure
to certain POPs with reproductive, immunological, neurological, and other
problems in marine organisms and humans. In Mozambique, for example,
more than 100 factories in and around the capital city of Maputo do not have
waste treatment plants; toxic wastes, poisons, non-degradable substances,
and organic matter are drained into coastal waters. These toxins can kill or
contaminate marine life; people who eat seafood from polluted areas or who
swim in contaminated waters are vulnerable to gastric and other infections.
Contaminants and activities that destroy coastal habitats and ecosystems also
contribute to the loss of the marine fauna on which many people rely for food
and income. Maintaining a healthy coastal habitat is critical because most of
the world's fish produce their young inshore and feed on organisms in coastal
waters. Breaking the marine food chain reduces vital supplies of protein for
about 1 billion people, most of whom live in developing countries.
Yet restricting fishing rights and access to coastal waters in order to project
marine fauna may harm vulnerable groups of people. Poor women depend
especially heavily on fish and fishing. They tend to fish close to the shore and
use the catch to feed their families, whereas men typically engage in largescale commercial fishing offshore or in major inland water bodies. Operating
on a smaller scale, women who fish earn only 40 percent of what men earn
for fishing in El Salvador. The situation is similar in rural Honduras, where
women earn about half of what men do.
Being less visible in their work, women are also less likely to have access to
decision-makers or to be consulted about the management of natural
resources. In the early 1990s, community leaders in El Salvador informally
banned fishing in estuaries due to concerns about the overfishing of shrimp
and other sea life in the estuary. Women were not consulted in this process
and lost a vital source of household protein and income. Women usually have
different access to and control over land and water in coastal zones: Fewer
than 5 percent of beneficiaries of land reform in El Salvador and Honduras
were women.
Integrated Coastal Management
Managing population pressures in coastal zones is difficult because those
regions encompass many physical, social, and regulatory divisions. In
addition, multiple competing economic sectors, including tourism, fishing,
agriculture, aquaculture, forestry, manufacturing, oil and gas extraction, waste
disposal, marine transportation, and real estate development have interests in
coastal zones. Governments usually manage each sector separately, if at all.
Consequently, many coastal nations have experienced rapid uncontrolled
development along their coastlines.
In a growing number of countries, coastal zone managers are adopting
integrated, multidisciplinary approaches to resource management that
incorporate the perspectives of all stakeholders, including governments, the
private sector, non-governmental organizations (NGOs), and individuals.
Integrated coastal management (ICM), an internationally accepted approach
to managing resources that is based on the United States' 1972 Coastal Zone
Management Act, allows policymakers and planners to take population issues
into account when looking at the pressures, threats, and opportunities facing
coastal areas. ICM has been endorsed repeatedly in international
conferences, including the 1992 UN Conference on Environment and
Development in Rio de Janeiro, Brazil, and the 2002 World Summit on
Sustainable Development in Johannesburg, South Africa.
ICM attempts to forge a balance between users of water and natural
resources while ensuring that long-term environmental health and productivity
are not compromised. Countries may use ICM to address the depletion of
coastal and ocean resources; deal with pollution that endangers public health;
distribute the economic benefits of using the coast and ocean; or develop and
manage coastal and marine areas that are not yet being exploited.
At least 107 of the world's 134 coastal developing nations are involved in
some type of ICM effort at the national or sub-national level. In general, the
most successful ICM efforts share several characteristics:
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Multiple stakeholders, including representatives from all levels of
government, NGOs, indigenous groups, communities, and the private
sector;
A strong scientific foundation to inform the management process;
A formalized mandate and funding mechanisms;
Formal decision-making that incorporates social, environmental, and
economic data;
Public participation starting at the initial stages of policy formulation
and program development;
Community-based management initiatives to develop community
experience, build support, and provide information about regional or
national programs;
Capacity building of local experts through training, education, and
applied research;
Strong outreach services that provide information and education to all
levels of management; and
Regular collection of reliable data to measure the success of
management initiatives.
Future Steps in Addressing Population Issues in Coastal Regions
Managing coastal areas requires concerted multi sectoral efforts by
government institutions at all levels, the private sector, and community
groups, as well as sustained political support. Achieving a balance between
top-down legislative authorities and bottom-up community involvement
requires understanding issues and maintaining strong links with stakeholders
in the area.
Efforts to balance local interests with national legislation need to consider the
socioeconomic context of coastal populations and what role demographic
patterns play in the region. Policymakers and program managers can take
several steps to address and integrate population concerns into their coastal
management efforts.