Transport Canada says it's lifting speed restrictions for cargo ships in the Gulf of St. Lawrence after recent surveillance failed to detect North Atlantic right whales in shipping lanes.

The agency said in a statement released Friday evening that the government's aerial surveillance team monitored shipping lanes closely over the past month.

It says its National Aerial Surveillance Program spent 240 flight hours in 44 missions scouring the waters.

They say whale surveillance will continue and that speed restrictions will resume if right whales are found in shipping lanes.

The interim slowdown was first implemented in April and expanded in area in June and July.

Transport Canada says during the slowdown period that vessels started using routes other than shipping lanes, including zones where right whales are known to gather.