First it was the giant panda, then the polar bear, now it seems that the grizzly bear is the latest species to face impending disaster.

A furious row has erupted in Canada with conservationists desperately lobbying the government to suspend the annual bear-hunting season following reports of a sudden drop in the numbers of wild bears spotted on salmon streams and key coastal areas where they would normally be feeding.

The government has promised to order a count of bears, but not until after this year's autumn trophy hunts have taken place. It has enraged ecology groups which say that a dearth of salmon stocks may be responsible for many bears starving in their dens during hibernation. The female grizzlies have their cubs during winter after gorging themselves in September on the fish fats that sustain them through the following months.

"I've never seen bears hungry in the fall before, but last year they were starving," said British Columbian wildlife guide and photographer Doug Neasloss. "I noticed in the spring there weren't as many bears coming out, but I felt it was premature to jump to conclusions." But now, he said, "there just aren't any bears. It's scary."

It was the same story, he said, from other guides over 16 rivers where once they would have been encountering dozens of grizzly bears. "There has been a huge drop in numbers. I've never experienced anything this bad." Reports from stream walkers, who monitor salmon streams across the vast territories, have been consistent, according to the conservation group Pacific Wild – no bears, and more worryingly, no bear cubs.

"There are just no bears out there, I'm hearing that from every side now," said Ian McAllister from Pacific Wild. He said that because a few grizzlies have been wandering close to centres of human habitation people thought there were plenty of bears around. "In fact it's the shortage of food that's driving them into town. They're starving," he explained.

In one river alone, the Fraser on Canada's west coast, 10 million sockeye salmon were expected back to spawn there this summer. Only one million turned up. Canada's Ministry of Environment announced in July that it would ban hunting of grizzly bears on an additional 470,000 hectares, bringing the total protected area for grizzlies and black bears to 1.9 million hectares.

The news came after Jane Goodall, the renowned wildlife campaigner, added her voice to the campaign against the hunts, which are for trophies, not meat.

"I'm very distressed and shocked that the bear hunt – grizzly bear and black bear – is continuing in a country like Canada," she said. "These bears are such amazing, magnificent creatures and there are so many secrets still to discover about their lives."

Grizzlies once roamed across most of North America and the Great Plains until European settlers gradually pushed them back. Only 1,000 remain in the contiguous US, where they are protected, but the number is less clear in the vast wilds of Canada and Alaska, where they are prized by hunters who shoot hundreds of the 350kg giants every year, providing a lucrative income for provincial governments that license the hunts. "It's appalling wildlife management, considering the widespread concern for coastal bears at the moment," said McAllister.

Indigenous groups have added their voice to the call to save the bears, pointing out that trophy hunting is against their traditions and threatens tourism, which is a vital source of income for the remote areas of Canada.

But a senior biologist with the US National Wildlife Federation said the evidence remained anecdotal and called the reports "alarmist". Bears would not starve so quickly because of the decline in salmon while there were other food sources, such as berries, around, Sterling Miller told reporters. He said the long-term impact of the salmon decline on bears was a serious issue, but several years of data would need to be compiled to reveal a change in population trends.

A report released last week showed species numbers to have fallen dramatically in the province of Alberta, where local officials have decided to suspend the annual hunting season despite intense lobbying from hunters. "There's no question that bears are worse off now than 20 years ago – both in numbers and range," said Jim Pissot, of the group Defenders of Wildlife.