Extended periods of summers or winters, unusual rains, extreme droughts or floods and many more natural calamities that human started experiencing is depicting one phenomenon: Climate Change. Climate of any region refers to averaged weather over a period of 30 years or more and climate change refers to a significant and lasting change in the statistical distribution of weather patterns, over a period ranging from decades to million. According to IPCC, climate change refers to a change in the state of the climate that can be identified by changes in the mean and/or the variability of its properties and that persists for an extended period, typically decades or longer, this could be naturally or can be caused by the anthropogenic agents. However United Nations Framework Convention on Climate Change (UNFCCC) considers only those changes which are in addition to the natural climate variability observed over comparable time periods and are attributed directly or indirectly to human activity that alters the composition of the global atmosphere.
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Within the past 100 years global temperature has increased approximately 0.6 °C, and is projected to rise by 2 to 4 °C by the end of this century (IPCC 2007). This increase in earth surface temperature cause glaciers shrinkage, melting of ice, sea level rise, changes of large ocean currents, shifts in the rainfall, evaporation and runoff pattern and thus affecting regional weather system and considerably influencing human and other life forms. Carbon dioxide is considered to be the main causative force attributing to climate change along with other greenhouse gases like methane, nitrogen oxide etc., which induces the warming of earth surface.
Climate change is the biggest global challenge before mankind and fisheries is one of the sector which seems to be under imminent threat as alteration in water flow, fluctuation in water temperature and alteration in water quality influences the metabolic rate which regulates the important activities like feeding, digestion, growth rate, maturation, breeding and survival of fish. According to Natural Resource Defence Council (NRDC) global warming lead to disappearance of Salmon and Trout as much as 18 to 38 per cent of their habitat by the year 2090. And India having a vast coast line (8129 kms) is highly vulnerable to effects brought about by climate change and the rise in sea level can cause an ecological disaster (UNEP, 1989). This articles deal with enlisting some of the major impacts climate change will have on marine fisheries.
Impact on physical environments
As the temperature is increasing, the oceans are warming, but with geographical differences and some decadal variability. Global average sea level has been rising since 1961, but the rate has been accelerated since 1993. Higher frequency and intensity climate processes, such as El Niño-Southern Oscillation (ENSO), and decadal-scale regime shifts, are expected to continue, with possible increases in their intensity or/and frequency in coming decades. Warming is more intense in surface waters but is not exclusive to these, with the Atlantic showing particularly clear signs of deep warming. Changes in ocean salinity have been observed, with increasing in salinity in near-surface waters in the more evaporative regions near to equator, and high latitudes showing decreasing salinity due to greater precipitation, higher runoff, melting ice and advection. The oceans are also becoming more acidic, with likely negative consequences to many coral reef and calcium-bearing organisms. Although there are no clearly discernible net changes in ocean upwelling patterns, there are indications that their seasonality may be affected. It is very likely that over the short term (within a few years), there will be negative impacts on the physiology of fish in localities where temperature increases, through limiting oxygen transport.
Impact on biological functions and fish stocks
Although large regional differences exist, especially at regional scales, most models predict a slight decrease in primary production in the seas and oceans and many models predict composition shifts to smaller phytoplankton which are likely to lead to changes in food webs in general. Changes in fish distributions in response to climate variations have been observed, generally consisting of pole ward expansions of warmer-water species and pole ward contractions of colder-water species. Changes are likely to affect pelagic species more rapidly than other species groups. Some examples of responses to climate change by different marine species are discernible in the Indian seas. (1) Until 1985, almost the entire catch of Oil sardine and Indian mackerel was from the Malabar upwelling zone and the catch was either very low or there was no catch from latitudes north of 14 °N. In the last two decades, however, the catches from latitude 14 °N to 20 °N are increasing which shows an extension of distributional boundary and a positive correlation was found between the catches and sea surface temperature (SST). (2) During 1970-2007, the catches of Catfish from southwest and southeast coasts decreased. On the other hand, the catches from the northwest and northeast coasts increased during the same period. It shows the strong negative correlation between catfish catch and SST along the two southern coasts and positive correlation between catch and SST along the northern coasts and hence a good example of shift in latitudinal distribution and abundance (3) During 1985-1989, only 2% of mackerel catch was from bottom trawlers, and the rest of the catch was contributed by pelagic gear such as drift gillnet where as in 2003-2010, 15% of mackerel catch is contributed by bottom trawlers along the Indian coast which shows a shift in the depth of occurrence of mackerels. The Indian trawlers operate at a depth ranging from 20m to 80m by employing high opening trawlers. As the surface waters are also warming up, it appears that the mackerel, being a tropical fish, has extended its vertical boundary to deeper waters. (4) data on the number of female spawners of threadfin breams Nemipterus japonicus and N. mesoprion collected every month off Chennai (south-east coast of India) from 1981 to 2010 indicated a trend in the shifting of spawning season from warmer (April – September) to cooler months (October – March) was discernible.
Impact on fishers and fishermen communities
Other than the direct impact of climate change on the present day human life, there are a lot of indirect impacts which adversely affects the fisher which are as varied as the climate change themselves. Impacts would be felt through changes in capture, production and marketing costs, changes in sales prices, and possible increase in risks of damage or loss of infrastructure, fishing tools and housing. Fishery-dependent communities may also face increased vulnerability in terms of less stable livelihoods, decreases in availability or quality of fish for food, and safety risks due to fishing in harsher weather conditions and further from their landing sites. Within communities and households, existing gender issues related to differentiated access to resources and occupational change in markets, distribution and processing, where women currently play a significant role, may be heightened under conditions of stress and increased competition for resources and jobs stemming from climate change.
Communities located in deltas, coral atolls and ice dominated coasts will also be particularly vulnerable to sea level rise and associated risks of flooding, saline intrusion and coastal erosion. Coastal communities and small island states without proper extreme weather adaptation programmes, in terms of infrastructure design, early warning systems and knowledge of appropriate behaviour, will also be at high risk. Salination of the agricultural fields due to seawater intrusion is negatively impacting the agriculture field, however this leads to taking aquaculture as major adaptive measure and thus adaptive role as an alternative livelihood, compensating for income and some aspects of food supply.
Impact on Coral reef ecosystems
Risks to coral reefs are not distributed equally. Three different time scales can be identified for climate change-related impacts to coral reef systems:
years: increased temperature effects on coral bleaching;
decades: increasing acidification and dissolution of carbonate structures of reefs;
multidecades: weakening of structural integrity of reefs and increasing susceptibility to storms and erosion events.
Increasing acidity (decreasing pH) is a significant and pervasive longer-term threat to coral reefs. Potential for coral reef systems to adapt to these environmental stresses is uncertain: symbiotic zooxanthellae may adapt to be more tolerant of high temperature whereas migration of corals to higher latitudes is unlikely. These declines in corals will have negative impacts on reef fish biodiversity along with the putting pressure on the integrity of the eco-system.
Positive Impacts of climate change
Some of the positive impacts includes
Increased food conversion efficiencies & growth rates due to warmer waters;
Increased primary production would provide more food for filter-feeding invertebrates;
Increased length of the growing season & range expansions to pole wards due to decrease in ice;
Sea level rise also has the potential to flood coastal land areas, mangrove and sea grass regions which may supply seed stock for aquaculture species.
Shortened duration of larval cycles can also help in the availability of seeds.
Potential adaptation measures in fisheries
A wide range of adaptations is possible, either carried out in anticipation of future effects or in response to impacts once they have occurred. In general, responses to direct impacts of extreme events on fisheries infrastructure and communities are likely to be more effective if they are anticipatory, as part of long-term integrated management planning. However, preparation should be commensurate with risk, as excessive protective measures could themselves have negative social and economic impacts.
Examples of potential adaptation measures in fisheries
Impact of climate change on fisheries
Potential adaptation measures
Access higher value markets/ shifting targeted species.
Increase effort or fishing power.
Reduce costs to increase efficiency.
Exit the fishery.
Increased variability of
Design insurance schemes.
Change in distribution
Migration of fishing effort/strategies and processing/distribution facilities.
Exit the fishery.
flooding, sea level and
Add new or improved physical defences.
Rehabilitate infrastructure, design disaster response.
Integrated coastal management.
Set up early warning systems.
Increased dangers of fishing
Set up weather warning system.
Invest in improved vessel stability/safety/ communications.
Influx of new fishers
Support existing local management institutions, diversify livelihoods.
Potential adaptation measures in post-harvest, distribution and markets
Both capture fisheries and aquaculture feed into diverse and spatially extensive networks of supply and trade that connect production with consumers, adding significant value and generating important levels of employment. To some extent, this system can be used to provide an important mediation and buffering function to increasing variability in supply and source location, but direct impacts will also affect its ability to do so. A range of issues and adaptation measures can be considered.
Table: Climate change-related impacts potential adaptation in post-harvest/distribution
Impact on post harvest, distribution/markets
Potential adaptation measures
Reduced or more variable yields, supply timing
Source products more widely, change species, add value, reduce losses
Develop more flexible location strategies to access materials
Improve communications and distribution systems
Reduce costs to increase efficiency
Temperature, precipitation, other effects on post- harvest processes
Change or improve processes and technologies
Improve forecasting, information
Vulnerability of infrastructure and
communities to extreme events
Add new or improved physical defences, accommodation to change
Rehabilitate infrastructure, design disaster response
Set up early warning systems, education
Trade and market shocks
Diversify markets and products
Provide information services for anticipation of price or market shocks
Management and institutional adaptations
Ecosystem approaches to fisheries (EAF) and to aquaculture (EAA) that embed precautionary approach applications within integrated management (IM) across all sectors have the potential to increase ecosystem and community resilience and provide valuable frameworks for dealing with climate change. This would create flexible management systems and support decision-making under uncertainty.
Where aquaculture could be used for adaptation in other sectors, planning would be required at appropriate system and management scales, such as watersheds, and estuaries. These approaches would serve to provide guidance in understanding and minimizing perverse incentives that lead to overcapacity, overfishing, excessive environmental impact and other harmful practices while, at the same time, defining positive incentives to meet sustainable development goals. Well defined sectoral performance criteria need to be set out to bring climate change threats, risks and potential adaptations within normal management practice. Public and private sector linkages and partnerships will be essential in developing efficient and effective responses. Market demands will be key mechanisms in supporting adaptation, and their impacts on equity among suppliers, intermediaries and consumers will need to be recognized and applied. Thus certification systems, including sustainability, organic, fair-trade and other criteria will need to be addressed more carefully in the context of climate change, and consider the potential for more vulnerable groups to take advantage of economic opportunity. Adaptation will need to contain strong mechanisms for equity, as increased competition may reduce access for poorer people and other vulnerable groups to production, employment and consumption.
For the global issue of the climate change we can contribute through some of the goals which are given below:
raising awareness of the impacts of climate change, to ensure that the special risks to the fishery sector are understood and used to plan national climate change responses, including setting of mitigation targets through mechanisms such as the Kyoto Protocol;
reducing fuel subsidies granted to fishing fleets, to encourage energy efficiency and assist towards reducing overcapitalization in fisheries;
supporting the use of static-gear – pots, traps, longlines and gillnets, which uses less fuel than active gear such as trawls and seines – and therefore emits less CO2;
restoring mangroves and protecting coral reefs, which will contribute to CO2 absorption, coastal protection, fisheries and livelihoods;
managing aquaculture to optimize carbon retention, reduce energy use and minimize impacts on mangroves and other important habitats; and
Raising awareness through seafood campaigns, reducing food miles, and promoting corporate social responsibility in the commercial sector.
promoting research on short- and medium-term climate change impacts to support the identification of vulnerability hot spots and the development of adaptation and mitigation strategies, including financing and risk reduction mechanisms aimed at enabling integrated and broader national planning;
addressing other issues contributing to vulnerability of the sector’s communities, such as access to markets and services, political representation and improved governance; and
Engaging in long-term adaptation planning, including promotion of fisheries- and aquaculture related climate issues in Poverty Reduction Strategy Papers and National Adaptation Programs of Action, to address longer-term trends or potential large-scale shifts in resources or ecosystems.
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