Effects of climate change on fish stocks

M. Ramar1, D. Kesavan1, S. Monikandon1, R. Palani2, Tamil Nadu Dr. J. Jayalalithaa Fisheries University 1College of Fisheries Engineering 2Dr.MGR Fisheries College and Research Station, Thalainayiru Nagapattinam - 611 002, Tamil Nadu, India

2021-08-25 16:13:28

Credit: pixabay.com

Credit: pixabay.com

Climate change is the statistical change in the course of time over a period of decades from decades to millions of years. It can be a change in the average season or a change in the events around an average season. (e.g., more or less severe seasonal changes). Climate change may be localized to a particular region or to the entire earth. These may be recurrent, often cyclical, climatic patterns; or come as single events that can be referred to as a dust storm.

In recent usage climate change especially in terms of environmental protection policy, usually refers to changes in the current climate. It can be referred to as climate change due to human activities; more generally, it is called global warming or "global warming caused by human activities".

Although climate change will intensify by 2050 and the effects of climate change cannot be accurately predicted, the potential for greater impact of the climate challenge becomes clear. Climate change is one of the most important global environmental challenges affecting food production, including fisheries and aquaculture, ecosystems, freshwater supply and health. Climate imagery developed by computer models shows that India may experience hot and humid conditions as a result of the effects of climate change and climate change on aquatic ecosystems, including increasing the frequency and intensity of heavy rains and extreme weather events (EWE), Sea Surface Temperature (SST) elevation and changes related to the anatomy of the organism or indirectly by sea acidification, directly by hydrological changes and sea level rise.

Climate change in fisheries habitats

Marine ecosystems are not in a stable state, but are affected by the environment. It varies in many spatial and temporal measurements. Fishermen respond to variation in different ways. Decades of variation can have unintended consequences, including cyclical changes in the production levels of marine ecosystems that may be favorable to one species or group to another.

Impact on fish stocks

A 10% increase in metabolism is equivalent to an increase in temperature of 1°C, with seawater less than 1°C affecting the distribution and life processes of fish physiology. This barrier causes distribution, recruitment and numerous changes. Time changes of biographical events are expected with climate change. Species with short lifespan and rapid returns of generations such as plankton and small pelagic fish are likely to experience such changes. At intermediate time scales ranging from a few years to a decade, the distribution, recruitment, and numerous changes of many organisms can be drastic at the peak of the organism’s limits. Numerous changes can change the composition of species and cause changes in the structure and function of ecosystems. In long-term measurements of decades, it is possible to make changes in net primary output and shift to higher file levels.

Time changes of biographical events can also occur as a result of global warming. Many tropical fish stocks have already become highly temperature tolerant and are already facing regional extinction and may move towards some higher latitudes. Many commercially important fish stocks, such as threadfin bream, already have changes during the spawning season. Changes in the distribution patterns of two major species in Indian fisheries have already been established. Migration patterns have changed drastically in the last 50 years with Indian oilseeds and Indian mackerel.

Ocean-atmospheric combined climate models predict changes in ocean cycles and suggest that changes in ocean cycles may stimulate the production of phytoplankton biomass in nutrient depleted areas in the open ocean. The effect of atmospheric CO2 is uncertain because the relationship between enhanced primary production of CO2 and air-sea exchange is not understood.

Most models show a reduction in primary production by converting the phytoplankton compound into smaller forms, albeit with greater regional variation. Significant effects on plankton distribution are observed in parallel with changes in ocean surface temperature. These changes may affect the distribution of fish stocks prior to plankton. Ocean acidification is believed to have adverse effects on marine tannins, specifically counting organisms, which are at risk of dissolution. Primary productivity decline is also predicted.

Impact on fish stock availability

There is evidence to increase the damage caused by extreme weather events over time, especially hurricanes, and there are various explanations for this. The higher the population density, the wider the effects of climate change. Until the mid 1980s, a controlled supply of herring oil ensured that all of herring oil was available off the southwest coast of India. North of 14°N, herring oil has not been caught before. Over the past two decades, however herring oil catchment has gradually and steadily increased from 14°N to 20°N, contributing 15% to the all-India herring oil catch in 2006. Since capture in the southwestern regions has not decreased overall, this indicates an expansion of the central fish oil supply range.

Studies of the seasonal distribution of skipjack tuna show that during the winter months, when the sea surface temperature is low, they migrate to the oceans, and during the warmer months, they migrate to the coastal areas. Changes in sea surface temperature due to global warming may cause changes in the seasonal distribution of some organisms and may eventually interfere with their harvest, which is generally based on domestic knowledge. Changes in distribution boundaries have the potential to raise subtle questions about fisheries rights, especially in the context of geopolitics and the exploitation of resources within neighboring exclusive economic zones.

Impact on the harvest field

Climate change affecting distribution also affects fishing methods used to harvest affected fish stocks. In the Bay of Bengal, rising sea surface temperatures have increased the depth at which fishermen cast their nets. Studies have shown that oil slick and Indian mackerel recruitment and capture increase in the post-monsoon period as a result of increased temperatures.

Changes in wind direction and speed adversely affect the yellow fin tuna fisheries off the southeast coast of India. During the months of October-January the tuna are favorable for fishing from north to south, with tuna moving with the wind and going from the deep waters of the sea to the shallow waters of the nearby coast. In Mumbai, studies on sea surface temperature against a unit effort per hour revealed a slight positive correlation between the two parameters. This means that with rising temperatures, a certain amount of energy has to be expended to harvest a certain amount of fish.

Studies confirm that the impact of fishing pressure on fish populations is much greater and more widespread compared to sea surface temperatures. However, since 14% of species are susceptible to changes in sea surface temperature, fishing control measures should be increased in parallel with conservative management measures. This may increase the vulnerability of organisms to vulnerability to climate change.

Impact estimates made by surveys of 8000 households in coastal villages in India have revealed that the level of knowledge about the effects of climate change is insufficient, requiring further input from government agencies and stakeholders.

A potential impact from climate change is an increase in the frequency of extreme weather events and damage to the fisheries sector. Hurricanes of sufficient strength can damage equipment and fishing facilities, as well as disrupt fishing activities. Life cycle estimates performed in the fishing industry show that most of the emissions from the fishing industry are generated during the actual harvest phase.


The impact of climate change on Indian fisheries has become clear through scientific studies conducted by leading national organizations. These climate parameters affected the country’s fisheries sector, creating challenges to food and nutrition security. The research also revealed changes in the anatomy of fish species and the three-dimensional dynamics of water. Changes in germination season, changes in maturity, reduction in average length and change in distribution of fish species were identified. They have implications for stock availability, capture, livelihoods and the national economy.