One of the Southern Hemisphere's biggest seasonal populations of killer whales or orcas have begun congregating at the Bremer Bay canyon in Western Australia.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Listen Duration: 8 minutes 32 seconds 8 m Marine scientists discuss the significance of the Bremer Bay canyon ( Fiona Pepper ) Download 3.9 MB

The deep sea canyon lies 70 kilometres off the coast of the small town of Bremer Bay, 180 kilometres east of Albany in Western Australia's Great Southern region.

It is thought that during a six-week period in summer a cold, salty current flows from the Antarctic, filling the canyon and picking up hydrocarbons or deep water fossil fuels.

This salt-rich, nutrient-filled water then hits the surface and attracts all sorts of marine life, including killer whales, sharks, dolphins, sperm whales and giant squid.

The discovery of this biological hotspot is relatively new, expeditions out to the canyon only began two years ago and marine scientists are still grappling with what is drawing this concentration of marine life to this particular spot for a short period of the year.

Dolphins dart in front of the boat at the Bremer Bay canyon. ( ABC Rural: Fiona Pepper )

When in 2005, Dave Riggs was contracted to observe marine wildlife onboard a Japanese tuna research vessel, Bremer Bay canyon was one of the areas covered.

"During that expedition I just noticed an unusual amount of activity … to put it in simple terms it smelt different, it felt like there was something special about this place," Mr Riggs said.

For the next 10 years Mr Riggs continued to study the canyon, and he said it all fell into place after contacting an oil and gas company conducting seismic activity in the area, which confirmed what he was observing.

Mr Riggs now runs daily expeditions out to the canyon, attracting both tourists and marine scientists.

Given the environmental significance of the canyon, he hoped to have the area protected from oil and gas exploration long into the future.

However, a spokesperson from the Australian Petroleum Production and Exploration Association said there were currently no oil and gas exploration leases covering the site and any decision to release a permit would be up to the federal government.

This week a group of officials with close ties to Western Australian tourism and regional development travelled to the canyon to witness the biological hotspot.

After visiting the site, Minister for Tourism Kim Hames said it was important the canyon be preserved.

"This is something that you wouldn't see in many places around the world, so we need to take an opportunity like this and work out how we can preserve it and make sure everyone else knows about it," he said.

A baby killer whale blows water as it reaches the surface of the water at the Bremer Bay canyon. ( ABC Rural: Fiona Pepper )

Every day brings something new for scientists

The abundance of apex predators that gather at the canyon over summer offers marine scientists a unique opportunity to conduct their research.

PhD candidate at Curtin University, Bec Wellard preparing equipment to record the bioacoustics of killer whales. ( ABC Rural: Fiona Pepper )

Sammy Andrzejaczek is eight months into her PhD at the University of Western Australia, focusing on the movement and diving behaviour of sharks, in particular the blue shark.

Blue sharks are commonly caught by fishermen and it is believed the predators follow killer whales on the hunt.

Ms Andrzejaczek hoped to tag the sharks and monitor their diving behaviour.

"We want to see how closely related they are to the killer whales, maybe they're following the pod to scavenge off the prey they have killed," she said.

Curtin University PhD candidate Bec Wellard has been monitoring the acoustics of killer whales.

Ms Wellard's research hopes to determine what dialects killer whales have and if they differ among varying locations and pods.

"Killer whales in the northern hemisphere have different dialects per family group so I'm interested in different dialects here in the Australian region," she said.

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