Hay River RCMP said on Friday their search for four missing fishers was "in recovery mode" and would be scaled back after five days with no sign of the men.
Relatives of the fishers began a land search of the Great Slave Lake shoreline on Friday in a bid to find their loved ones.
On Thursday, police had said the likelihood of the men remaining alive was low.
They have been missing since leaving Hay River by boat early on Sunday to check their nets. Their submerged boat was found on Tuesday, near the lake's west ocast.
"While a vast portion of the Great Slave basin has been searched for the missing fishermen, the search operation became focused on an area between the south shoreline and Windy Bay area, after the discovery of the fishermen's boat," read an RCMP statement on Friday.
"Fishing debris, believed to be from the identified vessel, was located in the open water in the area. However, there have been no sightings of the missing fishermen after four days of searching.
"Under the circumstances and with the low probability of survival, RCMP are now scaling back the search effort and proceeding with a recovery mission."
The missing men are Stacy Linington, a 59-year-old from Hay River, and three fishers from the area of Lesser Slave Lake, Alberta: 51-year-old Daniel Courtoreille, 50-year-old Michael Courtoreille, and Jason Fulton, 40.
Sgt Brandon Humbke of Hay River RCMP said: "It’s been a difficult week for friends and family of the missing four men. They were well-known and respected fishermen.
"We are working hard to try to collect any information and evidence that could bring answers to their loved ones as to what happened."
Police said they would remain in regular contact with the families, while cautioning people carrying out their own searches to "use extreme caution."
Posting online late on Thursday, Beatrice Lepine – a Hay River resident closely connected to the town's fishing community – said some family members would "be commencing a ground search along the shoreline" on Friday morning.
Lepine, whose grandparents were fishers, said the search would begin at Sandy Creek, on the Kátł'odeeche First Nation reserve, then move east toward Sulphur Point, where the fishers' nets had been.
Chief April Martel of the Kátł'odeeche First Nation wrote: "Anyone is more than welcome to assist."
Those who would like to help were told to call the First Nation's office at 867-874-6701. The First Nation was said to be providing boats and coordinating the search.
Lepine appealed for help rounding up items like binoculars, flagging tape, flashlights, and safety equipment ranging from bear spray to high-visibility vests.
"The families appreciate your support," Lepine wrote.
Members of the four men's families have been travelling to Hay River as the search continues.
Relatives have created a Facebook group, "Please bring the four fish men home safely," to share updates and provide support.