The sudden disappearance of northern pike from Watson Lake remains a mystery, says a fishery technician with the Department of the Environment.

'It's wierd,' Aaron Foos said simply, summing up how the namesake of the community went from a destination for anglers in search of trophy pike to a lake without a trace of a single pike in one year.

In the summer of 2002, anglers caught 1,680 of the feisty game fish, of which 158 were kept. The rest were released, according to an angling survey, Foos explained in an interview Tuesday.

In the summer of 2003, there is no known record of any pike being caught, nor did any of the species show up in an intensive search by Environment staff.

But the rest of the fish in the lake, the lake trout, the grayling, white fish and burbot are doing just fine, Foos said.

Watson Lake conservation officer Ryan Hennings said he received reports last spring from locals living on the lake and boaters of dead pike floating, though he never did recover any of the reported fish.

Hennings said he's not bothered by not being able to recover any of the dead fish, with wind, water currents, ice movements and the like that can push the carcasses around and take them back down to the deep.

He is bothered, like Foos and others, by the overnight disappearance of the pike.

Reports started coming in last spring of dead fish showing up, and concern became focused. Henningss started checking the shallow spawning beds used by pike, where they are normally clearly visible.

There were none.

In the summer of 2002, anglers were catching trophy pike in abundance. Seven months later, as the ice started to recede and the June spawning season for pike arrived, not a trace of a single live pike could be found.

Not an angler on the lake reported catching any pike, not even the most seasoned of the pike masters were catching fish, Hennings said.

'That is when we realized, that yep, we have a serious problem.'

Through the summer, the conservation officer intensified his patrols of Watson Lake to speak with anglers. He conducted his own net surveys. Still no pike.

Fisheries biologist Sue Thompson was dispatched from Whitehorse to the community last July to net for pike, as the mystery grew more pressing. After 24, one-hour sets, no pike, but lots of other fish.

A public meeting was held in the community last week to let Watson Lakers know that Environment staff do not have anything to explain the disappearance.

In the fall of 2002 at Halloween, Foos recalled, Hennings received a report from a lake resident of four pike dead under his dock.

Hennings retrieved the fish. He could see no visible signs of trauma, like blows to the head, or mouths scarred from fishing hooks. Nothing abnormal was apparent. Though unusual, the four dead fish on their own were not something to ignite an indepth scientific investigation.

It was the following spring when the disappearance of northern pike began to become evident that the fish recovered by Henningss the previous fall were sent to various experts for examination, Foos explained.

He said a search began for similar stories of pike being wiped out in a blink of an eye, with no impact on other fish.

There was a case in Vermont where 80 per cent of the pike population was killed off by a species-specific virus.

Examination of the carcasses recovered by Henningss in the fall of 2002 show no evidence of the virus, nor do they show any evidence of anything one might expect to explain the situation, Foos confirmed.

He said there are no signs of contamination by any toxic substance.

Besides, said Foos, one would expect something foreign like a toxic material would not just target pike, but would also affect the other species in the lake.

There's also no evidence of effects on the pike living in the lake above which, drains into Watson Lake, he said.

Foos said where the Department of Environment is going in terms of implementing some sort of management plan is very much contingent on what this spring brings.

The conservation officer said he and other Watson Lakers are planning to keep a close eye on the spawning beds after spring breakup, and he plans to do more test-netting to see if he can recover even a pike minnow.

Foos said one lake-area resident is sure he saw a juvenile northern pike last fall.

The popularity of Watson Lake had grown through the 1990s as a lake with large northern pike.

He said it was not unusual to catch 20-pounders, and pike more than 40 pounds were not abnormal.

Working from the catch-and-release figures of 2002 with nearly 1,700 pike caught, it would not be far-fetched to think there were upwards of 20,000 pike in the lake when the die-off began, he said.

Derrick Rothermel, of Kamloops, B.C., came to know the abundance of the northern pike in Watson Lake by chance, but has visited the lake every year since he hooked onto the northern gold in 1998.

As a lifelong pike fisherman who uses a fly rod, and who grew up on the Prairies where a large pike is 28 inches long, Rothermel said he immediately became tied to Watson Lake after his first night of fishing.

'I have never seen pike like that in my life,' Rothermel said this morning from Kamloops.

In one evening, between 5:30 p.m. and 1:30 a.m., he hooked into close to 50 northern pike, 24 of them over the length of 41 inches, which is described in the Yukon's angling guide as a trophy size.

'One or two I hooked that night were over 50 inches,' he said.

As a member of the worldwide pike fishing fraternity, Rothermel recalled how he told fellow anglers around the globe of his Watson Lake experiences. Many would only believe him after he sent videos and photographs.

He recalls boating through one shallow bay where he looked down to see what were apparently logs logs he did not recognize from before but took notice of, as any angler worried about his propellor would do.

Upon closer inspection, the logs were fish. From his side of the boat, Rothermel could see the heads. His fishing partner could see the tails on the other side of the boat, which measured 58 inches across. And in just a metre of water, there was not much distortion.

'So how big do you think those fish were?' Rothermel asked.

Every year since 1998 he came, sometimes with angling friends in tow.

He was here for the 2002 season, and while it seems to him the fishing was slightly off from previous years, it was still phenomenal.

And he was here last spring.

'We fished for three days and never saw one pike,' he recalled. He noted he was fishing with longtime Watson Laker and angler Dale Rudd, who also runs a taxidermy business.

'Oh, it broke my heart. And Dale said I do not know what is going on here,' and he said, I have never seen anything like this.'

'He just could not believe it. I mean, we checked every nook and cranny and could not come up with anything, not even a minnow. I have never seen anything like it.'