When travelling up the glacial rivers that thread through parts of New Zealand’s rugged South Island Jackie Adams often uses his 1,500CC motorbike to move quickly over the shingle beds.

But in his line of business speedboats and helicopters can come in handy too.

“No-one expects someone from the government to cruise up a river on a motorbike,” said Adams.

The former British Army colonel’s unique job is to hunt for illegal gold miners, an increasingly large number of them who work the ground at night.

It is a job this burly Irishmen who served in Bosnia during the war never imagined he’d be doing - especially alone in the remote ‘wild west’ of the south island, where the summer season of illegal gold-mining is just beginning to heat up.

“A lot of these cowboys, they think that gold just jumps into their hands,” said Adams, who also worked as a police detective in New Zealand, heading the CIB unit on the west coast.

“But they have no real knowledge or feel for mining and they are giving the fourth and fifth generation miners on the coast a bad-name.”

With the price of gold recently fetching nearly NZ$1800 (£1000) an ounce, Adams has been brought in by New Zealand Petroleum and Minerals to investigate the black market trade; mostly conducted by opportunists who sneak onto private farm land and national parks without permits to fossick for gold.

The modern-day gold rush is particularly evident on the coast, with the region’s mining history and crumpling traditional employment paths attracting prospectors from around the country - and the world.

Using diggers, metal detectors and even the humble shovel and pan, these hopeful amateurs are willing to wade through frigid west coast creeks in the middle of the night - once awash with gold swept down from the Southern Alps - and still concealing hundreds of millions of dollars worth of the precious metal.

“A lot of people have jumped on the bandwagon, there are probably thousands mining illegally in New Zealand, and a few hundred making a full-time living off it - we’re in the midst of a modern day gold rush, not just in New Zealand, but world-wide, although New Zealand is particularly attractive because it is a very stable country,” said Dan Gerber, who sells mining equipment over the internet.

“Humans have gone crazy over this metal for thousands and thousands of years. I caught the virus called gold bug more than 30-years-ago, and there is no medication; ever since then I have been hooked.”

The original West Coast Gold Rush kicked off in the 1860s, and the settlements of Hokitika and Ross sprung up around it, the setting of Eleanor Catton’s 2013 Booker prize -winning novel The Luminaries.

At the height of the rush Hokitika had 72 hotels and few women; those were the days when the ‘wild West Coast’ earned its reputation as a lawless region; catnip for adventurous pioneers and eccentrics. Like today the original miners were secretive about their claims, often laying false trails and misinformation to lure their competitors away from prosperous sites.

More than a century later, Hokitika is still home to a number of thriving gold shops and plastic pans and shovels are available to rent and buy at several places in town.

At The Gold Room in Hokitika trays of glittering gold rings studded with nuggets line the window display; with cheaper flakes of delicate west-coast gold mounted as stud earrings, and rubies and diamonds woven into necklaces to break up the rows and rows of tinsel-bright yellow metal.

Owner Barry Rooney, a former butcher, says the price of gold has doubled in the 15 years he has owned the shop; and modern technology has made even historic West Coast mining sites lucrative again.

“We have people offering to sell us gold all the time, they just walk into the shop,” says Rooney.

“We know a lot of the people we are dealing with but it’s still an old-fashioned trust thing. If they say they have found it in such and such an area we can only take their word for it - we are not policeman.”

That’s where Adams comes in. He is the first investigator of his kind hired by NZPM, after they became increasingly concerned about small and medium sized illegal mining operations making sizable money from gold that belonged to the crown.

“There is a large black market,” says Adams, who is in the process of prosecuting six people for illegal mining, and uses government satellite imagery, google earth and tip-offs from locals to scour the dense back country bush, sometimes alone, and sometimes with a geologist, Department of Conservation ranger or police back-up.

“Some of these cowboys have a history of mining and after the big down-turn of mining on the west coast in the 1990s they have the experience but no jobs. Others have jobs in the day but are mining at night, selling it quietly for cash to jewellery shops and cash converters - they’re simple opportunists.”

According to the latest figures from NZPM gold production is at its highest level since 2009; increasing from 583kg in 2014, to 750kg last year; a leap of nearly 30 percent.

There are 17 gold fossicking sites open to the public in New Zealand, but as most are easily accessed by road they are largely of interest only to hobbyists and tourists, as a shovel and pan is the only equipment permitted to be used on the sites. Everywhere else a permit is required to mine, of which there are currently 400 granted.

Dean McNamara runs the popular website mineforgold.co.nz and is the great-grandson of a gold miner who died in a west coast gold mine. He caught the “bug” over twenty years ago and compares fossicking to the thrill of buying lottery tickets.

“There is mining in my blood and when the world economy is so fragile it makes gold an attractive commodity to find and hold on too,” he said. “For some people there is a nostalgic element to it as well, of continuing the west coast traditions, of getting out in the New Zealand bush - the thrill, the excitement, the possibilities - there has always been an adventure side to it; a lot of people really feel they are one pan away from striking it rich.”

Adams says descendants of the original west-coast miners are quickly getting fed-up with unskilled opportunists galloping into the industry, and trampling up their backyard with heavy-handed operations, which are damaging to their reputation and the environment.

Many, he says, have become good informants, determined to defend their profession, and keep the rich back-country to themselves, and their families.

“I am getting more tip-offs and information from the west coast locals than anywhere else in the country,” says Adams.

“Mining has been a massive part of the culture on the coast and they are really proud of that tradition; for a lot of people it has been their entire lives and put their children through school. So these dodgy fellows coming in, they’ve got no time for and nor do I. ”