He said as with previous years a number of Indonesian and Papua New Guinean boats had also been caught.

Fisheries expert Professor Colin Simpfendorfer​ from Queensland's James Cook University said a rise in the price of sea cucumber or beche de mer, low diesel prices and strong fish populations were also behind the trend but the diplomatic tensions were clearly a factor.

"With China building islands up and creating military installations that's driven some of the fishermen who have historically worked in that area to other areas and that includes coming to Australia," he said.

Dr Simpfendorfer said it cost Australia "millions" to pick up the boats, hold the fishermen in immigration detention centres and destroy the boats, not to mention the damage to marine sanctuaries.

While the number of boats and fishermen has come down dramatically since the historic highs in the early 2000s, 147 Vietnamese fishermen have been apprehended by the Australian Border Force for fishing on board 10 boats since March. In 2015 no Vietnamese fishing boats were apprehended.

Twenty foreign fishing boats were captured in the 2015-16 financial year, compared with six in 2014-15.

Diplomatic tensions


Relations between the countries that have claims to various bits of the South China Sea have come under pressure this year because of the election of Rodrigo Duterte's pro-China government in the Philippines, uncertainty over US power in the Pacific following US President-elect Donald Trump's victory and tensions in ASEAN – arguably giving China "the upper hand" to pursue its agenda in the contested seas.

China has ignored a July ruling by a UN court in the Hague against China's 'nine-dash line' line of control.

Director of International Security at the Lowy Institute, Euan Graham, said while it is not "game over" in the South China Sea, China has had a good four to five months.

In recent years China has also been stricter at enforcing a fishing ban in the Gulf of Tonkin, which Vietnam says violates its sovereignty.

The Vietnam Fisheries Society says the move impedes the work of its fishermen.

In an article in Vietnam's Bien Phong, a state media outlet that belongs to Department of Border Defense, authorities point the finger at "forces" preventing their fishermen operating in the country's exclusive economic zone.

"In fact, in recent years, the South China Sea dispute has been complicated. Foreign forces threaten, scare away Vietnamese fishermen operating in waters under the sovereignty of Vietnam and the disputed waters. Their fishing areas, therefore, have been increasingly shrunk and exhausted," Bien Phong journalist Van Tanh wrote in August.

Indonesia also has shifted to a stricter enforcement regime around illegal fishing, which has seen the nation blow up 234 foreign boats since December 2014.


Aaron Connelly, of the Lowy Institute, argues that Indonesian President Joko "Jokowi" Widodo has taken a more nationalistic and unilateral approach to the South China Sea due to "an increase in Chinese incursions" around a remote set of islands in the far southern end – part of Indonesia's exclusive economic zone.

Vietnamese Coast Guard's High Command, Colonel Tran Van Nam, blamed the wave of arrests on China's expansionism and other South East Asian countries tightening control over their own waters in response.

"For a long time our fishermen were used to fishing in foreign waters without being arrested," he said.

But in the last two or three years, law enforcement forces of other countries [such as Indonesia and Malaysia] have been tightening their control."

There is a human toll. Poor fishermen, often the major breadwinner, can spend months in immigration detention when they are caught as the Vietnamese embassy wrangles with Australian authorities to free them and ship captains face court and are often slapped with fines, even when they were only obeying orders.

In one case that attracted publicity, Vietnamese fisherman Nguyen Xuan Thanh was thrown into Australian immigration detention for eight weeks for illegal fishing before he was released in August, according to Vietnamese media reports.

Mr Thanh is known in Vietnam for discovering and reporting that a Taiwanese company called Formosa was poisoning waterways and causing mass fish deaths.

He was caught fishing for sea cucumbers in Australian waters north of Queensland in April with about 20 others. His family was now struggling and his absence had a big financial cost, according to the reports.


Sixteen Vietnamese fishermen caught with three tonnes of sea cucumber were given two- to four-month sentences in the Darwin Magistrates Court in November. In other cases fines of a few thousand dollars have been given to the masters of the ships, where shark fin and turtle meat have been found on board as well as tonnes of sea cucumber.​

Further reports in Vietnamese media suggest that the heavy indebtedness the ship captains and their owners face in order to buy the boats was also a factor.

One ship captain said it cost $US630,000 to build a ship, which meant he had to take on as much as $US314,000 to $US358,000 in bank loans.

"If I only fish around our waters God knows how long it will take before I can pay back my debts. Therefore I had to take risks, even though I knew I could get caught," he told Vietnamese channel VTV4.