Climate change will have strong impact on fisheries

The UN food agency’s note of caution came at the start of a four day scientific symposium on climate change and marine fisheries being held at its Rome headquarters (8-11 July 2008). The event, which involves over 200 experts and policymakers from around the globe, aims to paint a fuller picture of the challenges that climate change poses to marine fisheries and the millions of people who depend on them for food and income.

High degree of vulnerability

Wild capture fisheries are fundamentally different from other food production systems in their linkages and responses to climate change and in the food security outcomes that result, according to FAO.

Unlike most terrestrial animals, aquatic animal species used for human consumption are poikilothermic, meaning their body temperatures vary according to ambient temperatures. Any changes in habitat temperatures significantly influence their metabolism, growth rate, productivity, seasonal reproduction, and susceptibility to diseases and toxins.

Impacts already being felt

Impacts of climate change on fisheries and aquaculture already being observed include:

In marine waters, climate processes and extreme weather events will increase in frequency and intensity – the most well known of these is the El Niño phenomenon in the South Pacific.

The ongoing warming of the world’s oceans is likely to continue, but with geographical differences and some decadal variability. 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 fish distributions in response to climate variations have already been observed, generally involving poleward expansions of warmer-water species and poleward contractions of colder-water species.

Shifts in ocean salinity are occurring, with near-surface waters in the more evaporative regions of most of the world’s oceans increasing in salinity, while marine areas in high latitudes are showing decreasing salinity due to greater precipitation, higher runoff, melting ice and other atmospheric processes.

And the oceans are becoming more acidic, with probable negative consequences to many coral reef and calcium-bearing organisms.

Implications for food security

Although large regional differences exist, the world is likely to see significant changes in fisheries production in the seas and oceans, FAO says.

For communities who heavily rely on fisheries, any decreases in the local availability or quality of fish for food or increases in their livelihoods’ instability will pose even more serious problems.

Fishing communities located in the high latitudes and those that rely on climate change-susceptible systems, such as upwelling or coral reef systems, will have the greatest exposure to climate-related impacts. In addition, fisheries communities located in deltas, coral atolls and ice dominated coasts will be particularly vulnerable to sea level rise and associated risks of flooding, saline intrusion and coastal erosion.

But countries with limited ability to adapt to the changes, even if located in low risk areas, are also vulnerable.

FAO also noted however that the impacts of climate-related physical and biological changes in fisheries on the communities that depend on them will be as varied as the changes themselves. Both negative and positive impacts are likely, depending on local circumstances and the vulnerability and adaptive capacity of the affected communities.

A key sector at risk

At both the local and global levels, fisheries and aquaculture play important roles in providing food and generating income. Some 42 million people work directly in the sector, the great majority in developing countries. Adding those who work in associated processing, marketing, distribution and supply industries, the sector supports several hundred million livelihoods.

Aquatic foods have high nutritional quality, contributing 20 percent or more of average per capita animal protein intake for more than 2.8 billion people, again mostly in developing countries.

Fish is also the world’s most widely traded foodstuff and a key source of export earnings for many poorer countries. The sector has particular significance for small island states.

Accordingly, FAO is increasingly focusing its attention on how climate change will affect fisheries and aquaculture.

In April, the agency convened a workshop of experts to look at climate change implications for fisheries and aquaculture in advance of the June 2008 summit on food security, climate change, and bioenergy. That group generated an overview document which looks at the issues and risks involved, and also outlined possible responses governments and policymakers could make to begin to adapt as well as highlighting the responsibility of the sector vis-à-vis its role in minimizing its carbon footprint.

This week’s symposium is intended to deepen and broaden scientific knowledge on how climate change is affecting marine ecoystems and the communities that depend on them.

The symposium is being co-sponsored and co-organized by FAO, Global Ocean Ecosystem Dynamics (GLOBEC) and European Network of Excellence for Oceans Ecosystem Analysis (EUR-OCEANS).

source: FAO