Maarg Manthan · Topic 12.5

Energy and Biotic Resources of the Oceans

Geography › Coral Reefs, Ocean Resources and Law of the Sea · Topic 12.5

The oceans supply energy from offshore oil and gas, offshore wind, tides, waves, ocean thermal energy conversion and gas hydrates, and biotic resources such as fish, shellfish, seaweed, pearls and marine medicines. Overfishing, pollution and warming now threaten these resources, so sustainable use is the central aim of the blue economy, in which India is a major fish producer.

6 min read · UPSC Prelims · Geography · Coral Reefs, Ocean Resources and Law of the Sea

At a Glance

Energy forms Tidal, wave, OTEC, offshore wind, hydrates
OTEC needs Temperature difference of about 20 degrees Celsius
Biotic resources Fish, seaweed, pearls, medicines
Overfishing More than a third of fish stocks
India Second largest fish producer
Exam link UPSC Prelims, Geography: Coral Reefs, Ocean Resources and Law of the Sea

Where Does It Fit?

This is the fifth topic of the category on coral reefs, ocean resources and the law of the sea. The previous topic described the mineral deposits of the sea, and this one covers the energy and living resources. The last topic of the macro covers the law that governs the use of the sea. Previous topic: copper, cobalt Regulator International Seabed Authority,…">Ocean Deposits and Mineral Resources. Next topic: UNCLOS, Territorial Waters and Exclusive Economic Zone.

What Energy Can the Oceans Provide?

Source	How it works	Status and India
Offshore oil and gas	Drilling on the continental shelf and in deep water	About a third of world oil production; Bombay High is India’s largest offshore field, and the Krishna-Godavari basin has deep-water gas
Offshore wind	Turbines at sea, where winds are stronger and steadier than on land	Fast growing in Europe and China; India has a coastline suited to it off Gujarat and Tamil Nadu, with a national policy since 2015 and support for the first projects approved in 2024
Tidal energy	Turbines driven by the rise and fall of the tide, as in Tidal Bore and Importance of Tides	Predictable, but limited to sites with a high tidal range
Wave energy	Machines that convert the up-and-down motion of surface waves to electricity	Still at the pilot stage; an Indian pilot was tested off Vizhinjam in Kerala
Ocean thermal energy conversion (OTEC)	Uses the difference in temperature of at least about 20 degrees Celsius between warm surface water and cold deep water to run a turbine	Suited for tropical islands, as in Temperature Distribution of Oceans; India’s NIOT built a low-temperature thermal desalination plant at Kavaratti in Lakshadweep
Salinity gradient and currents	Energy from the difference between fresh and salt water, or from strong currents	Experimental
Gas hydrates	Methane trapped in sediments of the slope	Large resources in India’s Krishna-Godavari, Mahanadi and Andaman areas; extraction is not yet commercial

What Are the Biotic Resources of the Ocean?

Fisheries: the oceans give about 80 million tonnes of wild-caught fish and other seafood a year, and aquaculture now supplies about as much again. The best fishing grounds are on the continental shelf, where warm and cold currents meet and upwelling brings nutrients, as in Effects of Ocean Currents: the Northwest Pacific, the Northeast Atlantic, the Peruvian coast and the Indian Ocean. India is the second largest fish producer in the world, with a coastline of over 7,500 km, after China.
Seaweed: used for food, agar and alginates, fertiliser and biofuel; India is promoting seaweed farming along the coast of Tamil Nadu, Gujarat and Lakshadweep, and has set up a multipurpose seaweed park at Ramanathapuram.
Shellfish, pearls and corals: oysters, prawns, mussels and pearls, such as at Tuticorin in the Gulf of Mannar.
Marine biotechnology: sponges, corals, and microbes provide compounds for medicines, such as anticancer drugs.
Mangroves and coastal ecosystems: nurseries of fish, protectors of coasts and stores of carbon, as in the Sundarbans.

How Sustainable Is the Use of Ocean Resources?

The FAO estimates that more than a third of the world’s marine fish stocks are fished beyond sustainable limits, and the share has been rising for decades. Overfishing, destructive methods such as bottom trawling, bycatch, subsidies that support the overcapacity of fleets, illegal fishing, pollution and warming of the sea are the key causes, as in Temperature Distribution of Oceans. The collapse of the cod fishery at the Grand Banks in 1992 is a standard example, as in The Atlantic Ocean.

The concept of the blue economy, the sustainable use of ocean resources for growth, jobs and ocean health, is the response. Instruments include catch limits, closed seasons such as the annual fishing ban of 61 days in Indian waters, marine protected areas, the global target to protect 30 per cent of the oceans by 2030 under the Kunming-Montreal Global Biodiversity Framework, and the new treaty on the biodiversity of the high seas, the BBNJ Agreement, which was due to come into force in January 2026 after reaching the 60 ratifications needed. India’s policies include the Pradhan Mantri Matsya Sampada Yojana, launched in 2020 to raise fish production and to modernise the sector, and the Deep Ocean Mission, as in Ocean Deposits and Mineral Resources. As an analytical point, small-scale fishers, who are the majority of Indian fishers, depend on the nearshore stocks that are under the most pressure, so the sector needs better data, credit and cold storage as much as it needs regulation.

Why Is This Topic Important?

Concepts OTEC and blue economy asked
India Fisheries and offshore wind
Sustainability Overfishing and treaties

What Came Next?

The last topic of the macro describes the law of the sea, territorial waters and the exclusive economic zone. Next topic: UNCLOS, Territorial Waters and Exclusive Economic Zone.

Key People and Terms

OTEC Energy from ocean temperature difference
Offshore wind Wind farm at sea
Overfishing Catching fish faster than they reproduce
Bycatch Unwanted catch of other species
Blue economy Sustainable use of ocean resources
BBNJ Biodiversity Beyond National Jurisdiction agreement

Exam Corner

Points to Remember

OTEC needs about 20 degrees Celsius difference.
India’s annual fishing ban is 61 days.
More than a third of stocks are overfished.
30 by 30 is the ocean protection target.
PMMSY was launched in 2020.

Do Not Confuse With

Tidal and wave energy Tide range versus surface waves
Capture fishery and aquaculture Wild catch versus farmed fish
Blue economy and fishing industry Sustainable sector-wide use versus one sector

Memory Hook

Wind, tide, wave and heat power the sea; fish feed us, but only if we leave enough in the water.

Mains Angle

Questions ask for potential and sustainability. These points add depth.

Energy Offshore wind and OTEC
Food Fisheries and seaweed
Governance Blue economy and BBNJ

A Question You May Face

An original practice question, not a past paper question.

“Discuss the energy and biotic resources of the oceans and the challenges of using them sustainably, with reference to India’s blue economy.”

How to Answer

Energy Forms and status.
Biotic Fish and seaweed.
Problems Overfishing and warming.
Policy Blue economy and treaties.

GS Relevance

Prelims: forms of ocean energy, OTEC, fishing grounds, overfishing, blue economy policies. GS Paper 3: renewable energy, fisheries, blue economy.

Frequently Asked Questions

What is ocean thermal energy conversion?

Ocean thermal energy conversion, OTEC, produces electricity using the temperature difference of at least about 20 degrees Celsius between warm surface water and cold deep water. It is suited for tropical areas with deep water close to the coast, such as islands, and can also provide fresh water by desalination.

What are the main forms of ocean energy?

The main forms of ocean energy are offshore oil and gas, offshore wind, tidal energy, wave energy, ocean thermal energy conversion, salinity gradient power and gas hydrates. Offshore oil and gas and offshore wind are developed at scale, while the others are still at an early stage.

Why are some parts of the ocean rich in fish?

Fish are abundant where nutrients reach the sunlit upper layers, as on shallow continental shelves, in areas of upwelling, and where warm and cold currents meet. These conditions support plankton blooms that feed the food chain, as in the Grand Banks, the seas around Japan and the Peruvian coast.

What is overfishing?

Overfishing is catching fish faster than the stocks can reproduce, leading to decline or collapse of the population. According to the FAO, more than a third of the world's marine fish stocks are overfished, and the collapse of the Grand Banks cod fishery in 1992 is a well-known example.

What is the blue economy?

The blue economy is the sustainable use of ocean and coastal resources for economic growth, better livelihoods and jobs while preserving the health of marine ecosystems. It covers fisheries, shipping, ports, offshore energy, tourism and biotechnology, and is a part of India's policy through programmes such as the Deep Ocean Mission.

PYQ Practice — Statement Analysis

1 OTEC works on the temperature difference between surface and deep ocean water.

True

A difference of about 20 degrees Celsius is needed.

2 Cold-water fish stocks have never been overfished.

False

The Grand Banks cod collapsed in 1992.

3 Seaweed is used to make agar and alginates.