Canada's sports fishery is rapidly declining and may collapse as the commercial cod and salmon fisheries did, researchers warn.

A new study says stocks of trout, walleye, pike and other fish are depressed, especially within a three- to four-hour drive of cities in Alberta, British Columbia and Ontario.

"Bottom line, if you're talking about stocks close to large urban areas, there are few stocks produced through natural reproduction anymore," said lead author and University of Calgary scientist John Post.

The Alberta fishery, especially, is in decline. Scientists keep track of 27 populations of walleye in the province and 21 of them have collapsed recently.

"It look as if the same sorts of collapses will develop in recreational fisheries as the commercial fisheries if we go with the status quo," said Post.

For example, in the 1980s, about 2,000 people fished in Alberta's Wolfe Lake each year, and one in four would have caught a walleye within an hour.

In the 1990s, about 10,000 people fished in the lake each year, and one in 50 would have caught a fish.

Post said the collapse of sport fisheries goes unnoticed because each one is so small and affects so few anglers.

One of the reasons for the decline is technology such as sonar that make it easier to catch fish, Post said.

He also recommended a lottery for fishing licences to reduce the total number of anglers across the country.

The study appears in the Journal of Fisheries Management.