Climate change and global warming are threatening the livelihood and the natural ecosystem. The fisheries sector is also greatly affected by the alarming impact of climate change, resulting in a decline in total production worldwide. According to the FAO report (FAO, 2020), globally, 59.5 million peoples are directly or indirectly involved with this sector and the total fisheries production in the year 2018 was 178.5 million metric tons (MMT). India is one of the major contributors to world fish production (8% of total production) and ranked second in inland production (Department of Fisheries, Govt. of India, 2020). The annual fisheries production from India, in the year 2019-20 was 14.16 MMT, where the majority comes from the inland sector (10.43 MMT).  Again, this sector contributes 1.24 % (2018-19) in total Indian GDP and 7.28 % of the total agricultural GDP (Department of Fisheries, Govt. of India, 2020). India has a huge potential in terms of fisheries resources (Figure 1) but due to rapid increase in the population growth and huge demand for fish increasing the tendency of overfishing and declining the stocks of few species. Climate change accelerates this process and acts as a dispensatory factor on fish populations. Several studies revealed that climate change has a strong impact on the fisheries sector with far-reaching consequences for food and livelihood security (Vivekanandan & Krishnakumar, 2010).

 Changes in hydro-climatic variables in India

Fisheries production largely depends on several hydro-climatic variables like sea surface temperature, salinity, chlorophyll, air temperature, pH, rainfall, sea level height, ELNINO, frequency and intensity of cyclones, drought, etc. (Kumar et al., 2009; Mohanty et al., 2017). The changing pattern of these variables in recent days is immensely observed and visible in future forecasts/predictions. India is blessed with two tropical basins, namely the Arabian Sea in the western part and the Bay of Bengal in the estern part. The oceanographic characteristics of these two seas are different from each other. The Arabian Sea has a high salinity level compared to the Bay of Bengal. This is mainly due to the Bay of Bengal receiving a large amount of freshwater discharge from the rivers during the summer monsoon. The tropical cyclonic events occur more frequently on the eastern coast of India, compare to the western part and the frequency has been increased in recent days, resulting in huge capital loss as well as increased vulnerability of the coastal livelihood. The marine fish production also decreased and due to intrusion of saltwater, the freshwater fisheries production is also affected as its increases the salinity level. Observed changes and future prediction of different climate and environmental variables in the Indian scenario may be summarized as follows:

i.     Indian Meteorological Department (IMD) reported that the average maximum air temperature over India has shown an increasing trend of 1 °C/100 years over the period 1901–2019 (George & Athira, 2020). Air temperature over the Bay of Bengal has increased at a rate of 0.019 °C/ year from 1985 to 2000 and a study found that if this increasing trend will continue, the average air temperature in this area may rise up to 1 °C by 2050 (Hazra & Bakshi, 2003).

ii.     In India, there is also a visible shift in the onset of the southwest monsoon, generally, it used to start at the end of May but now it has shifted to the second week of June.  Rainfall of monsoon and post-monsoon months showed a decreasing trend in India at a rate of 3.84 mm to 4.42 mm every year, whereas pre-monsoon rainfall showed an increasing trend (0.98 mm/year) (Mandal, 2005). 

iii.     The average sea surface temperature (SST) has been increased by 0.45°C along the east coast and by 0.67°C along the west coast during the period 1880-2014 (Mohanty et al., 2017).

iv.     The average mean sea-level rise along the Indian coasts was calculated as 1.3 mm/year from 1878 to 2004. Sea level predicted to rise by 2040 with compare to 2020 in  Mumbai coast by 0.12m; at Hiron Point in Sundarbans sea level will rise up to 0.17m; Cochin coast will likely rise of 0.15m and at Bhavnagar coast, sea level will rise up to 0.22m. (INCOIS, 2018)

v.     About 7 percent of global tropical cyclones occur in the north Indian Ocean and the east coast is more prone to cyclones. The study reported that the number of cyclones occurring in the Bay of Bengal (East coast) is four times more than in the Arabian Sea (West coast). Analyzing the data from 1891 to 2013 of tropical cyclone frequency over the north Indian Ocean has shown that there is a trend of enhanced cyclogenesis during four months i.e. May, October, November and December, while the maximum number of severe cyclone hits in the region on November due to increasing the temperature (Mishra, 2014).

vi.     The salinity level over the past three decades has been increased by 6 ppt (2 ppt/decade) in the eastern sector, which is much higher than the average of the Indian Ocean (0.01–0.02 ppt/ decade) (Mitra et al., 2009).

vii.     The pH level in Indian seas has been declining at a mean rate of about 0.002 every year. This is due to the increasing trend of the atmospheric CO_2, which added to the seawater resulting in decreasing the pH level and increasing the ocean acidification. The marine ecosystem is greatly influenced by the pH level of the water especially calcifying organisms like corals, foraminifera, pteropods, and coccolithophores, etc.

 Impacts of climate change in the Indian fisheries sector

Changing patterns of different hydro-climatic variables has been greatly influencing both the freshwater as well as marine fisheries sector. However, the effects of climate change have been observed more intended in the marine sector compare to inland fisheries (Mohanty et al., 2017). The pathways through which (Table 1) the potential impact of climate change can affect the distribution and production of fish stocks, the risk and viability of fishing operations and livelihoods have been described below (Allison et al., 2009)

Table 1: The potential impact of different climatic variables on the fisheries sector

The potential impact of climate change in the Indian fisheries sector can be described into two-part i.e. a) climate change impact on the marine sector and b) climate change impact on inland fish production.

A.        The potential impact of climate change on the Indian marine fisheries sector

The impact of climate change on different marine organisms responds differently. It effects on the habitats, geographic affinities, and biological traits of several species. Many species shift to higher latitudes in response to climate change. Most marine fishes shift their horizontal and vertical movements to avoid unfavorable climatic conditions. For, example to adapt to increasing sea surface temperature (SST), fishes used to move deeper parts of the sea or to different water masses. The other impact are changes in age/size at maturity, fecundity, growth, spawning, and phenology found as an indicator of climate change. The Indian marine fisheries sector is also greatly affected in terms of changing the growth rate, fecundity, spawning, and maturity age of several important species (Table 2). The increasing number of mechanized vessels increases the overfishing issue and restricts the juveniles to maturity stage and along with climate change, this becomes a serious concern for the government and the policymakers.

Table 2: Potential impact of climate change on different important fish species in India