Orca rules have been effective

American regulations that limit vessel noise and traffic around endangered killer whales off the West Coast are working, a new study says.

The U.S. National Oceanic and Atmospheric Administration, or NOAA, said in its review of regulations adopted in 2011 that the changes are benefiting southern resident orcas without having negative effects on the local whale watching and tourism industries.

The southern residents that ply the waters off British Columbia and Washington state are listed as endangered species in the United States and a species at risk in Canada.

The last census in July showed there were just 77 whales in the three pods that make up the population known to use the Salish Sea that includes the straits of Georgia, Juan de Fuca and Puget Sound.

The Center for Whale Research in Washington state said as of December this year there were 76 whales, down from 83 in 2016.

Regulatory changes implemented by the American government prevent vessels from going within 200 yards, or 182 metres, from the whales.

Vessels aren’t allowed to go in the path of the whales or try to intercept them.

“We know from the science that when boats are in close proximity to the whales, they don’t forage as much and possibly don’t forage as effectively, both because they’re disturbed by the presence of the vessels and possibly by the sound of the engines,” said Michael Milstein, a spokesman for NOAA.