British Columbia鈥檚 endangered population of southern resident killer whales are more likely to go extinct, now that the Liberal government has approved Kinder Morgan鈥檚 Trans Mountain pipeline, some environmental scientists say.

The whales, which roam the southern coast, are symbolically important for several First Nations and also attract tourism dollars.

Raincoast Conservation Foundation, a scientific body that advocates for wildlife issues, says it is considering legal action since the government greenlit the contentious project, which would significantly increase tanker boat traffic in the Salish Sea, where the 80 whales live and hunt salmon.

Even without an oil spill or whales being struck by tankers, the group fears that persistent boat noise would overpower the orcas鈥 ability to hunt and communicate using echolocation.

鈥淓ven if this project goes completely according to plan -- no ship strikes and no oil spills -- just the increase in noise alone dramatically increases the risk of extinction,鈥 Misty MacDuffee, a biologist and wild salmon program director for the group, told CTVNews.ca.

Similar concern for the orcas has been voiced by Green Party Leader and Saanich Gulf Islands MP Elizabeth May, who has vowed to go to jail if necessary to fight the project.

How tankers impact killer whales

To understand how boat noise could seriously affect the orcas, it鈥檚 important to understand how they hunt. Orcas that hunt fish 鈥 such as the southern residents 鈥 use chirps and clicks to size up a fish, locate its whereabouts and communicate with other whales amid the underwater hunt.

MacDuffee says that when tanker boats are in the region, those chirps and clicks become 鈥渕asked鈥 by the drone of engine noise.

鈥淔oraging decreases in the presence of boats. And right now in the Salish Sea, vessel traffic is present about 85 per cent of the time for whales,鈥 she said. 鈥淎nd we know that vessel traffic is going to go to 100 per cent.鈥

Southern resident orcas don鈥檛 live exclusively in the waterways between B.C. and Washington. The whales are known to swim up the western coast of Vancouver Island and travel as far south as California in colder months.

But the whales have evolved from generation to generation to rely on the chinook salmon hunt in southern B.C. during warmer months -- an instinctive behaviour that isn鈥檛 likely to change on a dime.

鈥淭here鈥檚 not a whole lot of other options. It鈥檚 not like they can switch their dominant food source. So they鈥檙e really relying on this general region for chinook,鈥 MacDuffee said.

To make matters tougher, the population鈥檚 diminutive size means that the loss of just a single whale has broad repercussions. If one whale doesn鈥檛 get enough to eat and starves or is struck by a tanker, the consequences affect the larger group.

What about B.C.鈥檚 other orcas?

Southern residents aren鈥檛 the only whales in B.C. There are also the northern resident killer whales, which naturally swim in northern waters, and seal-hunting transient orcas, which travel across the coast. MacDuffee says northern resident whales wouldn鈥檛 be directly affected by the Trans Mountain pipeline due to where they live, but transients could be seriously harmed by an oil spill.

MacDuffee said the southern residents are 鈥渙n a precipice鈥 and that, at the moment, their fate can fall either way. According to a population viability analysis by the Raincoast Conservation Foundation, the southern resident killer whales can be saved if noise in the region is reduced and food is made more available.

鈥淚f we take a different course, we can recover this population,鈥 she said. 鈥淏ut doing nothing isn鈥檛 going to recover the population. And adding horrific stressors is only going to make it worse.鈥

MacDuffee said the Raincoast Conservation Foundation plans to weigh its legal options in the coming days. The group has already challenged the National Energy Board鈥檚 decision to approve the project on the grounds that it didn鈥檛 adequately consider the Species at Risk Act, which stipulates that 鈥渟ignificant adverse effects鈥 cannot be placed on an endangered population.

She insisted that the loss of the southern residents wouldn鈥檛 simply be a sad day for science 鈥 it would be a cultural blow.

鈥淔or British Columbians, these are iconic animals that help distinguish who we are here on the coast,鈥 she said. 鈥淧ursuing something simply because it鈥檚 economically profitable for a certain segment of society, that鈥檚 just not good enough anymore. These trade-offs are no longer acceptable.鈥

Other whale researchers have spoken out against the project. Ken Balcomb with the Center for Whale Research said it was a 鈥渄ark day鈥 when the decision was announced Tuesday.

鈥淔ortunately there are other species of whales in other parts of the world that haven鈥檛 been destroyed yet,鈥 Balcomb said. 鈥淚f people want to whale watch, they鈥檙e going to have to go to those.鈥

With a report from CTV Vancouver Island