Big oil v orcas: Canadians fight pipeline that threatens killer whales on the brink

Conservationists say the proposed Trans Mountain Expansion project poses the greatest risk yet to a killer whale population on the edge of extinction

On one shore there are snow-capped mountains. On the other side loom towering skyscrapers. These churning waters off the coast of Vancouver are marked by a constant flow of ferries and containers ships - but they are also home to 80 or so orcas.

Known as the southern resident killer whales the group has long had a fraught relationship with the urban sprawl they live alongside, leaving them on the knife's edge of extinction.