The federal Fisheries Department has changed its practice of towing small vessels in ice following the recent deaths of four sealers whose boat capsized as it was being hauled behind a large icebreaker.

A department official said Wednesday that coast guard icebreakers will no longer tow vessels 33 metres or less in length if the crew of the stricken boat refuse to disembark.

Phil Jenkins said the change was made immediately after the deaths.

"The coast guard suspended its practice of towing small vessels in ice with crew aboard the disabled vessel while the internal safety review is underway," he said in an e-mail.

Jenkins wouldn't elaborate on the measure or explain why the department decided to changes its procedures.

He would say only that the restriction will be kept in place while the coast guard undergoes a review of its actions in the early hours of March 29, when a sealing vessel out of the Îles de la Madeleine, Que., went down off Cape Breton.

The Sir William Alexander icebreaker was towing L'Acadien II, a 12-metre sealing boat that lost its rudder in thick ice while taking part in the annual seal hunt.

What was an uneventful tow from the Alexander ended when the much larger ship swerved to dodge a massive chunk of ice in the otherwise relatively clear waters, one of two survivors from L'Acadien said last week.

The ice cake ended up directly in the path of L'Acadien II, flipping it on its side while the icebreaker reportedly kept pulling the small boat through the frigid waters.

The bodies of three men were later recovered from the submerged wreck, while a fourth is missing and presumed dead.

The decision not to tow crewed vessels seems to reiterate existing guidelines in the coast guard's towing precautions checklist, which recommends removing "all people from the disabled vessel when necessary, safe or practical."

A Newfoundland fisherman has said he was involved in a similar capsizing in 1997 and now believes crew on disabled vessels should be taken off during such tows.

Baxter Nippard, 60, said he called for a tow after his vessel got stuck in the ice and lost its steering in Bonavista Bay. As the vessel was being towed by the coast guard vessel Sir Humphrey Gilbert, his boat capsized.

None of his four crew members was injured.

The incident involving L'Acadien II has raised questions about the coast guard's handling of the capsizing and whether it followed limited guidelines it has on towing in ice.

Witnesses have said no one appeared to be monitoring the dangerous tow as it was taking place, although officials with the Transportation Safety Board of Canada have said otherwise.

The independent agency is also investigating the accident, as is the RCMP, and has said two coast guard crewmen watched as the icebreaker pulled the small boat up onto an ice floe before it capsized and started sinking.

One witness said he screamed into his radio repeatedly to alert the icebreaker crew to the sudden emergency but got no response.

Investigators with the safety board have been to Îles de la Madeleine, a cluster of Quebec islands north of P.E.I., to interview survivors and witnesses after speaking with crew aboard the Alexander following the accident.

Teams were also continuing their search for the sunken vessel to see if the missing sealer was trapped inside.