In spite of all the debates and controversies, a global consensus has been
reached that climate change is a reality and that it will impact, in diverse
manifestations that may include increased global temperature, sea level rise,
more frequent occurrence of extreme weather events, change in weather
patterns, etc., on food production systems, global biodiversity and overall human
well being.
Aquaculture is no exception.
The sector is characterized by the fact
that the organisms cultured, the most diverse of all farming systems and in
the number of taxa farmed, are all poikilotherms. It occurs in fresh, brackish
and marine waters, and in all climatic regimes from temperate to tropical.
Consequently, there are bound to be many direct impacts on aquatic farming
systems brought about by climate change. The situation is further exacerbated
by the fact that certain aquaculture systems are dependent, to varying degrees,
on products such as fishmeal and fish oil, which are derived from wild-caught
resources that are subjected to reduction processes. All of the above factors
will impact on aquaculture in the decades to come and accordingly, the aquatic
farming systems will begin to encounter new challenges to maintain sustainability
and continue to contribute to the human food basket.
The challenges will vary significantly between climatic regimes. In the tropics,
the main challenges will be to those farming activities that occur in deltaic
regions, which also happen to be hubs of aquaculture activity, such as in the
Mekong and Red River deltas in Viet Nam and the Ganges-Brahamaputra Delta
in Bangladesh. Aquaculture in tropical deltaic areas will be mostly impacted
by sea level rise, and hence increased saline water intrusion and reduced
water flows, among others. Elsewhere in the tropics, inland cage culture and
other aquaculture activities could be impacted by extreme weather conditions,
increased upwelling of deoxygenated waters in reservoirs, etc., requiring greater
vigilance and monitoring, and even perhaps readiness to move operations to
more conducive areas in a waterbody.
Indirect impacts of climate change on tropical aquaculture could be manifold
but are perhaps largely unknown. The reproductive cycles of a great majority of
tropical species are dependent on monsoonal rain patterns, which are predicted
to change. Consequently, irrespective of whether cultured species are artificially
propagated or not, changes in reproductive cycles will impact on seed production
and thereby the whole grow-out cycle and modus operandi of farm activities.
Equally, such impacts will be felt on the culture of those species that are based
on natural spat collection, such as that of many cultured molluscs.
In the temperate region, global warming could raise temperatures to the upper
tolerance limits of some cultured species, thereby making such culture systems
vulnerable to high temperatures. New or hitherto non-pathogenic organisms may
become virulent with increases in water temperature, confronting the sector with
new, hitherto unmanifested and/or little known diseases.
One of the most important indirect effects of climate change will be driven by
impacts on production of those fish species that are used for reduction, and
which in turn form the basis for aquaculture feeds, particularly for carnivorous
species. These indirect effects are likely to have a major impact on some key
aquaculture practices in all climatic regimes. Limitations of supplies of fishmeal
and fish oil and resulting exorbitant price hikes of these commodities will lead to
more innovative and pragmatic solutions on ingredient substitution for aquatic
feeds, which perhaps will be a positive result arising from a dire need to sustain
a major sector.
Aquaculture has to be proactive and start addressing the need for adaptive
and mitigative measures. Such measures will entail both technological and
socio-economic approaches. The latter will be more applicable to small-scale
farmers, who happen to be the great bulk of producers in developing countries,
which in turn constitute the backbone of global aquaculture. The sociological
approaches will entail the challenge of addressing the potential climate change
impacts on small farming communities in the most vulnerable areas, such as
in deltaic regions, weighing the most feasible adaptive options and bringing
about the policy changes required to implement these adaptive measures
economically and effectively.
Global food habits have changed over the years. We are currently in an era
where food safety and quality, backed up by ecolabelling, are paramount; it was
not so 20 years ago. In the foreseeable future, we will move into an era where
consumer consciousness will demand that farmed foods of every form will
have to include in their labeled products the green house gas (GHG) emissions
per unit of produce.
Clearly, aquaculture offers an opportunity to meet these
aspirations. Considering that about 70 percent of all finfish and almost 100
percent of all molluscs and seaweeds are minimally GHG emitting, it is possible
to drive aquaculture as the most GHG-friendly food source. The sector could
conform to such demands and continue to meet the need for an increasing
global food fish supply. However, to achieve this, a paradigm shift in our seafood
consumption preferences will be needed.
Presented in the Aquaculture 2010 conference proceedings, published in 2012 by the Food and Agriculture Organisation of the United Nations (FAO) and the Network of Aquaculture Centres in Asia-Pacific (NACA)
August 2012
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