Climate change to also majorly affect fish catches in our seas, rivers.
Climate change and a rise in sea temperature may result in the disappearance of reef-building corals along the Lakshadweep and Andaman and Nicobar coasts in 10 to 50 years. The distribution and harvest of different fish species in the Indian seas and major river systems may also alter perceptibly.
Sea surface temperature is anticipated to rise about three degrees by the end of this century. This is likely to impact marine flora and fauna in a major way.
This has been indicated by studies conducted under an elaborate “national network project” on assessing the impact of global warming and climate change on the Indian agro-ecosystems, launched by the Indian Council of Agricultural Research (ICAR). Around 15 research institutes are studying how agriculture, fisheries, livestock and other sectors will be affected and what can be done to mitigate the effect.
Coral reefs are known to be highly sensitive to climate influences and are among the most vulnerable of all marine living beings to temperature changes. Reef-building corals are currently the dominant creatures in the coral diversity in the Indian seas.
The ICAR studies have projected that the reef-building corals are likely to fade away as dominant organisms between 2020 and 2040 in the Lakshadweep region and between 2050 and 2060 in the Andaman and Nicobar waters.
These projections have taken into account only the effect of warming of ocean water. But since the rise in water temperature is also likely to be accompanied by an increase in the acidity of sea water, the adverse effect on corals may actually be worse. Higher acidity would dissolve the calcium carbonate that forms the skeleton of the reefs.
The studies on the effect of sea water warming on marine fisheries have revealed that some significant changes in the distribution of the fish species are already underway. The presence of oil sardines, which abound Indian coastal waters, has been extended to beyond their known boundaries in the.
Oil sardines did not exist in the northern and eastern latitudes along the east coast before 1976 but they are found there now, because the water temperature is now conducive to their survival.
“It is expected that the distribution of sardines may extend further to Gujarat and West Bengal coasts in the coming years, assuming that other fisheries-related physical and biological parameters will not vary considerably”, maintains P K Aggarwal, ICAR National Professor, who is engaged in compiling the results of the climate change studies.
However, if the sea surface temperature on the southern side increases beyond the optimum levels for fish, it may drive the fish population away from this zone, resulting in reduced catches along the south-west and east coasts.
Where river fishery is concerned, the studies have recorded some significant changes in fish stocks in the Ganga river system. The changes in the water flow patterns as a result of the factors related to climate change has lowered fish spawn (eggs) availability. Leading to erratic breeding of fish in the Ganga river. The fish landings have, consequently, declined from, on an average, 85.2 tonnes in 1959 to 62.5 tonnes in 2004.
Besides, there is a noticeable shift in the geographical distribution of fish in the Ganga. The warm water species (such as Glossogobius giuris, Punitius ticto and the like), available earlier in the middle stretch of the river, are now found in the relatively colder stretch of the river around Hardwar. This is attributed to the rise in river water temperature in recent years.
