Every fifth fish caught worldwide is done so illegally, the United Nations Food and Agriculture Organization says.

Meanwhile, sea-bordering countries are using military force to protect what they see as critical national assets.

With growing demand for the resource and scarcer quantities, the fight for fish is likely to intensify.

The battle for oil and water

There are similarities between the world's reliance on oil and a comparable dependence on fish.

"Oil is a very conflict-ridden sector," Johan Bergenas, a senior director of public policy at Washington DC-based technology firm Vulcan, tells Blueprint For Living.

"I believe there are some numbers that say 25 to 50 per cent of all conflicts, in one way or another, are driven by the lack of or access to oil."

Through his research, Mr Bergenas has identified parallels between oil and fish resources.

"There is a concentrated supply. The Middle East has nearly half the world's supply of recoverable crude," says Mr Bergenas.

"Similarly, the central Pacific has 60 per cent of the world's tuna which is a highly pursued commodity."

Sorry, this audio has expired Are the fish wars coming? Johan Bergenas talks to Jonathan Green.

This concentration of supply is likely to drive conflict.

"This is a critical commodity for the human condition", says Mr Bergenas.

"One billion people today rely on seafood for their primary source of protein."

He says unless we dramatically change how we think about the oceans and the riches that they hold, we're going to be in trouble.

"The last 10,000 years, one of the most common sources of conflict has not necessarily been over territory or ideology — it's been over access to natural resources.

'We have fought wars over agricultural lands, spices, sugar and a wide range of other more natural resources. So why not fish?"

Who owns the fish?

Establishing ownership over the oceans and respective fish populations is not always easy — fish move back and forth between territories.

Smaller countries find it harder to enforce treaties and laws governing their fishing boundaries. ( Getty: In Pictures Ltd )

Mr Bergenas says it is very difficult to survey these vast areas of water.

Even if keeping an eye on the thousands of kilometres of coastline was doable, the enforcement of the boundaries is a challenge for many small countries.

But for larger countries, the sea is literally their oyster.

Mr Bergenas says China has "perfected a strategy" where they send fishing vessels into disputed waters.

"When a different country attacks these fishing vessels ... the Chinese are sending in their Coast Guard and Navy to protect them.

"Bigger, hungrier nations like China and others will continue to use both military, diplomatic and economic power to gain access to waterways and territory that are fish-rife.

"Smaller, poorer countries are going to have an enormous amount of pressure on them to not only keep these countries out, but also enforce and go after violators."

'A matter of enforcement'

Fish consumption in less developed countries is expected to rise by 21 per cent by 2022. ( Getty: Sonny Tumbelaka )

There are approximately 70 or more treaties, laws and regulations that govern operations in the world's oceans, Mr Bergenas says.

So on paper, keeping the superpowers toeing the line should be easy.

"It isn't necessarily a shortage of the rule of law but it's a matter of enforcement," he says.

"Every country has the exclusive economic zones or rights to its natural resources in their waters."

But logistically, there are some hurdles for smaller countries to overcome.

"A radar reaches about 12 nautical miles from their territory, that is, even if they can afford or manage a radar on the coast.

"A fishing boat, maybe travelling at 12-15 knots, will take a couple of days to get to the broader outskirts of their exclusive economic zones where the illegal fishing boats are.

"So what we are up against over the next number of years, hopefully, is a global and sophisticated capacity building initiative that will help not only poorer countries but richer as well to have a better understanding of what is out there beyond the line of sight."

Climate change increases threat of conflict

The world has been fighting over limited resources since the beginning of time, but we are now seeing growing populations, scarcer fish resources and more competition for this marine protein.

Impacts of climate change on global fishing industry Recent studies show that 75 per cent of Pacific Island coastal fisheries will not meet food security needs by 2030

Recent studies show that 75 per cent of Pacific Island coastal fisheries will not meet food security needs by 2030 UN/World Bank are increasingly focused on declining fish stocks, and the ramifications for food security and economic development

UN/World Bank are increasingly focused on declining fish stocks, and the ramifications for food security and economic development United Nations report [2018] found many fish species are changing their distribution, which threatens to disrupt fishing as we know it

United Nations report [2018] found many fish species are changing their distribution, which threatens to disrupt fishing as we know it Source: Australian National Centre for Ocean Resources and Security (UOW)/CSIRO

As Mr Bergenas says, "there are very few outcomes that are good in that scenario".

Fish consumption in less-developed countries is expected to rise 21 per cent by 2022, according to Australian National Centre for Ocean Resources and Security.

Add to the pot the growing threat of climate change — hotter oceans mean fish are migrating to colder waters in search of relief.

There is also the increase of ocean acidification, more harmful algal blooms and decreasing coral reefs.

"Countries might lose entire stocks that they were reliant on for food, for work and for cultural and other historical values," Mr Bergenas says.

Have the fish wars started already?

Globally, fights are breaking out over scarce seafood resources.

"There was an engagement ... in the English Channel during the summer where French and English fishermen were fighting over, and trying to scuttle each other over, the scallops in the English Channel," Mr Bergenas says.

Dubbed the "scallop wars", a deal was reached in September over the long-running dispute.

"In the South China Sea, Indonesia's been blowing up 300 fishing vessels over the last number of years," Mr Bergenas says.

"Other engagements of military style capacity have happened in Africa and South America."

From Mr Bergenas's perspective, Australia and China are two countries that are taking water and the ocean as a natural resource seriously.

On the whole, it is not an ocean-dreamscape of a picture.

"The sustainable development goals and the resource commitments that are being made ... to oceans and ocean sustainability are among the lowest [priority].

"This is brewing a very dangerous pattern that we are seeing and we really need to find ways very, very quickly to do more about it."