M. S. Swaminathan Research Foundation, India

Presentation of Dr.Yugraj Singh Yadava (Director, BoBP) - Significant Points

Launch of WWF Report and Panel Discussion on

IMPACT OF CLIMATE CHANGE ON GLOBAL FISHERIES

Presentation of Dr.Yugraj Singh Yadava (Director, BoBP) - Significant Points

Surface water temperature is expected to rise up to 3 degrees in the next 100 years if the current rate of emission continues.
Some bodies of water may become too warm for the fish that inhabit those areas; but warmer temperatures may also enable fish in cold ocean waters to grow more rapidly.
The amount of oxygen may decline while pollution and salinity levels may increase.

Implications of global warming on different types of fisheries:

Inland Fisheries:

Most fish species tolerate seasonal variations in temperature, but have limits to how hot or cold the water can be before they must either find more hospitable temperatures or perish. Higher water temperatures lead to lower levels of dissolved oxygen. With the 700 F warming that could eventually occur, majority of rivers will have oxygen concentrations below the level necessary to support most fish.

Coastal Fisheries:

Wetland loss, salinity changes, and higher temperatures are all likely to affect finfish and shellfish in the coastal zone. Coastal marshes are the primary nursery grounds; most of the reproduction occurs in the part of the wetlands that are within about 50-100 feet of the open water. The species that either reproduce in coastal wetlands, spend their entire lifetimes in an estuary, or both would be the most severely affected. As sea level rises and inundates wetlands, the initial effect will be the increase in total area of marsh to which fish have access. Hence, sea level rise may initially increase the production of these species. As sea level continues to rise, however, the loss of marsh accelerates; and eventually most or all of the wetlands in an area are replaced by open bodies of water. Thus, in the long run, an accelerated rise in sea level would decrease production of these species.

Oceanic Fisheries:

Scientists generally expect fish on the high seas to be less affected by global warming than coastal and inland fisheries. Overall biological activity is greater at higher temperatures, more food is available, fish grow faster, and they reproduce at a younger age. However, this expected increase in fisheries from warmer temperatures might be partly offset, by a decline in the upward flow of deep ocean water to the surface (upwelling). Coral reefs have proved to be particularly sensitive to warming. As surface temperatures have risen in recent years, many reefs have bleached, and with further increasing temperatures over longer periods the corals die.

El Nino and Fisheries: El Nino results from changes in atmospheric pressure in the Pacific Ocean and is associated with higher sea surface temperatures and sea levels, lower nutrients, and increased intensity of storms and storm surges. Recent El Ninos have resulted in death of up to 98% of coral reefs in some regions. El Nino has wreaked havoc in stocks of sardines and anchovies in Peru, marine iguanas and kelp forests off California. It is believed that global warming itself may be increasing the frequency of El Nino.

For complete presentation click here

(1.16 MB)