Illegal fishing in Indonesian and East Timorese waters is driving a rise in the practise in northern Australia, according to an Australian academic.
In a Darwin court last week, six Indonesian fisherman pleaded guilty to attempting to steal trochus shell near Browse Island, off the Kimberley coast.
The crew received fines ranging from $2,000 to $6,000, and two repeat offenders were sentenced to immediate jail time.
Even with last week's charges, the situation is a dramatic improvement on illegal fishing from its peak in 2005, according to Australian Fisheries Management Authority general manager of operations Peter Venslovas.
But industrial scale illegal fishing in Indonesian and East Timorese waters is forcing poor and exploited fisherman from those areas to return to the illegal fishing practices in northern Australia that were once common, researchers are warning.
Illegal fishing cascade
Illegal foreign fishing in northern Australian waters peaked in 2005 with around 7,000 illegal fishing vessels sighted in Australia's exclusive economic zone.
But a series of border security operations reduced illegal incursions to less than a tenth of that number by 2007.
Since then, illegal fishing has steadily risen again, according to Professor Karen Edyvane from the North Australia Research Unit for the Australian National University in Darwin.
"Since about 2010 we've seen a major and sharp increase in what we call illegal fishing vessel activity," Dr Edyvane said.
Australia's policing of our maritime borders is not at fault, according to Dr Edyvane, who puts the increasing illegal fishing pressure down to the destruction of fish stocks in Indonesian and East Timorese waters by foreign-owned, long-range industrial fishing trawlers.
Better cooperation between Australian, Indonesian and East Timorese governments in fighting industrial-scale illegal fishing is the best way to prevent small-scale Indonesian fishing in Australian waters, she said.
"We've really got to be working together, all of us together, in terms of tackling the issues of illegal fishing."
Stopping boats helped exploited fishermen
Indonesian fisherman are also pressured to risk arrest in Australian waters by traders who finance their meagre operations and then demand increasing returns, according to Emeritus Professor James Fox from ANU.
"Most people don't know that the traders who buy the products from the fisherman are usually exploiting them," he said.
Dr Fox has studied small scale fishing on the Indonesian archipelago for over 30 years and has lived on the island of Roti on-and-off since 1965.
Despite befriending Indonesian fisherman who travelled to Australian waters to fish, he welcomed the crackdown on illegal fishing in the mid-2000s as it ended the exploitation that he said was driving the fisherman to act illegally.
Poor, small-scale Indonesian fisherman would become indebted to traders who would pressure them to take greater risks.
"They come down within the legal area, and then they sneak across further down towards the Australian coastline where the fishing is better," Dr Fox said.