The body of a person who is believed to be one of four men missing since yesterday from a fishing trip off the coast of Perth has been discovered by searchers west of Garden Island, police say.

Key points: Four men went fishing off Perth on Wednesday morning and failed to return

Four men went fishing off Perth on Wednesday morning and failed to return A major search by police and volunteers has found one body off the coast, south of Fremantle

A major search by police and volunteers has found one body off the coast, south of Fremantle The men's car and trailer remain at the boat ramp and no distress calls were made

Four men from the same family have been reported missing as a large-scale air and sea search between Perth and Rottnest Island continues.

Police said the body was yet to be identified and coronial investigations have begun.

The men set off from Woodman Point near Fremantle on Wednesday morning in a 5.5-metre boat for an overnight fishing trip to the island.

Sorry, this video has expired Search underway on Friday for men who failed to return from Rottnest fishing trip

No names have been released, but police confirmed among the missing were the 50-year-old owner of the boat from the southern Perth suburb of Coodanup, his brother believed to be aged in his 40s, the 24-year-old son of the boat owner and a 31-year-old man who was also a member of the family.

They were due back yesterday but never arrived.

"When they failed to return to Woodman Point at approximately 7:00pm, family members checked Woodman Point car park and found that the vehicle and boat trailer were still present at that location, and at that point they raised the alarm with police," Fremantle Police Inspector Sean Togher said.

The men's vehicle and boat trailer were found at the Woodman Point boat ramp. ( ABC News: Samia O'Keefe )

Police said members of the fishing party had been in contact with family and friends throughout their expedition, but there had been no contact since 3:30pm yesterday, and it was not known if the men had spent Wednesday night on the boat or on Rottnest Island.

"It was all very casual conversation from all the available information, basically reflective [of the fact that] that they'd been on the fishing trip and intended to return," he said.

An Australian Maritime Safety Authority rescue plane has been doing loops off the coast as part of the search. ( Twitter: @weather_wa )

Attempts to contact the men have been unsuccessful and police said there had been no sign of the group or their vessel on or around Rottnest Island.

No emergency calls were received from any of the men.

Men set out in severe weather

A severe weather warning was issued for the Perth metropolitan area on Wednesday night, with strong and damaging winds forecast.

Inspector Togher said there had been heavy fog around midnight.

"I don't think the actual sea conditions were treacherous, it was just a bit wet and windy," he said.

The men set off in a 5.5-metre boat called 'Yeah Buoy' but failed to return the following day. ( Supplied: WA Police )

Bureau of Meteorology observations show wind gusts on Rottnest Island reached speeds of 54 kilometres per hour on Wednesday night.

Speaking from aboard a search boat, Fremantle Sea Rescue volunteer Nick Hill said the conditions at the time were cause for concern.

Loading

He said his boat had been searching for more than 12 hours and the situation was becoming increasingly urgent.

"The ideal would be to find the boat floating with four people on board," he said.

"But by this time we have to be looking for boats in the water, upturned boats, damaged boats and people in life jackets."

The search currently involves nine search and rescue vessels, three helicopters and an Australian Maritime Safety Authority jet aircraft.

Emergency equipment not activated

Inspector Togher said weather conditions had been favourable for the search. More than 400 square kilometres of ocean had been searched by boat, and "the air search has been probably three times that area".

He said the operation remained a search and rescue mission and the men's survival would come down to many factors, including their level of fitness and what they were wearing.

The boat had a full suite of emergency equipment including an EPIRB, life jackets and flares, but neither the EPIRB nor the flares had been activated.

He said the family were "very concerned" and a family liaison officer had been appointed by police to assist them.

Rescuers say the search for the men is becoming increasingly urgent. ( ABC News: Kathryn Diss )

"We would expect that we would have found some trace of the vessel, but that is not to say the vessel hasn't drifted," Inspector Togher said.

He said the search area was based on both the vessel drifting and on the men being in the water.

"I would have expected that we would have seen some sign of it if the boat was afloat, unless of course it has been moored in a location that we are unaware of," Inspector Togher said.

He said the search would continue Friday evening and into Saturday "at the very minimum".

Water Police said they would like to hear from anyone who was boating at Rottnest Island yesterday and saw the white 5.5-metre vessel with four people on board.