The recent hot weather is creating difficult conditions for salmon in New Brunswick's famous Miramichi River. (CBC)

The hot temperatures that roasted much of New Brunswick last week also caused a tough time for the cold-water loving salmon in the Miramichi River.

Debbie Norton, owner of Upper Oxbow Outdoor Adventures, said she is usually busy this time of year, hosting salmon anglers who come to her outfitting business to fish on the famous Miramichi River.

That started to change as the temperatures soared past 30 C in the Miramichi region last week, hitting 36.3 C on Wednesday, 31.9 C on Thursday and 30.5 C on Friday.

"We have chosen not to fish until the weather gets better and what I mean by better is colder," Norton said.

Hot weather warmed up the river to temperatures less hospitable for the prized salmon.

"Of course when the water's hot, there's less oxygen in it, salmon are cold-water fish, they like cold water and so they're finding this a very stressful time," she said.

Dying salmon

Normally this time of year there are anglers all up and down the Miramichi River trying to catch one of the region's famous fish.

But the warm weather really slows that activity and Miramichi salmon observers say some salmon are not surviving the warmer waters

"We've been getting reports of a number of salmon dying — not only adult salmon, but even salmon parr," or young salmon, said Mark Hambrook, the president of the Miramichi Salmon Association.

Over the past decade, parts of the Miramichi River have failed to meet the spawning requirements needed to maintain a healthy population.

The Department of Fisheries and Oceans imposed a catch-and-release only policy for salmon on the Northwest Miramichi River on June 30. The number of salmon eggs in the Northwest Miramichi River has dropped dramatically in the past decade.

The salmon association says that last year only 34 per cent of the required number of eggs needed to preserve a healthy population was met.

Hambrook said the warmer water doesn't help the struggling salmon numbers.

"When the water temperature gets to 23 C, salmon have to start looking for cold water," Hambrook said.

"And if they happen to be in an area where they can't find cold water or there's too many fish to take advantage of the cold water, we start to see fish dying."