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Deep-sea octopus nursery discovered off Vancouver Island

“[They] sit on their eggs, don’t move, don’t eat and just defend the eggs for a minimum of four and a half years.”
A deep sea octopus, brooding on her eggs on carbonate rock, uses her dexterous arms to punch and successfully defend herself from scarlet king crabs. Northeast Pacific Deep-Sea Expedition Partnership and CSSF ROPOS

Sixty-five kilometres west of Hesquiat Harbour, north of Tofino, lives a nursery of deep-sea octopuses ­brooding their eggs. It’s one of four known octopus nurseries in the world, says DFO researcher Cherisse Du Preez.

In late May, Du Preez and her colleague Heidi Gartner set out on a deep sea expedition, in partnership with the Nuu-chah-nulth Tribal Council, Council of Haida Nation, Quatsino and Pacheedaht First Nation, Ocean Networks Canada and Fisheries and Oceans Canada.

The expedition was largely to explore the ­pending Marine Protected Area Tang.ɢwan-ḥačxʷiqak-Tsig̱is, ­alongside additional places of interest to protect, said Du Preez.

Months prior, the German scientific research ­organization GEOMAR and Natural Resources Canada discovered bubbles travelling 1.5 kilometres through the water column, indicating a methane seep from the seafloor, Du Preez said.

The group explored roughly 12 locations where gases escape from fissures in the ocean floor. They are among at least 1,500 offshore cold seeps west of Vancouver Island, extending from southern Vancouver Island to Haida Gwaii, she said.

On the last dive of the expedition, along Hesquiat slope, they came across a nursery of deep sea octopus brooding on their eggs within cave-like features in ­carbonate rock created by the cold seeps.

“The methane bubbles … that are bubbling out of the seafloor creates large chunks of methane ice,” said Du Preez.

“They actually create entire uplifts, and they tear the seafloor upwards.”

This process “creates carbonate rocks that are then habitat on the seafloor that otherwise weren’t there.”

“It’s almost volcano-like,” said Du Preez. “It’s ­bringing stuff up from deep within the earth, it’s ­creating rocks, and it’s all overflowing and then ­tumbling down and it builds up on itself.

“In this particular location we saw one of these ­blisters in the earth’s surface. We saw this violent ­bubbling coming out, and all the rocks that were being created and tumbling down the slope collected in this boulder field that was otherwise surrounded by ­desert-like, muddy abyss.”

According to a 2014 study, this particular deep-sea octopus, Graneledone boreopacifica, is known to have the longest-known egg-brooding period of any animal due to the cold temperatures of the deep sea waters. The embryonic development period slows down, ­compared to that for shallow water octopus, which brood their eggs from one to three months.

“It’s a beautiful deep-sea octopus, very charismatic, purple, big black eyes,” said Du Preez.

“[They] sit on their eggs, don’t move, don’t eat and just defend the eggs for a minimum of 4½ years.”

As with salmon, brooding these eggs will be the last thing these octopuses do, she said.

Cold seeps are recognized by the Canadian ­government as among ecologically and biologically ­significant areas.

“They are so standalone outstanding, with the ­biodiversity you find around them, that they warrant protection,” said Du Preez.

The nursery ground that Du Preez and her team ­discovered is located in an area that is fishable. “The most concerning thing about finding a nursery ­somewhere where fishing can happen is [that] it can be that easy to take out a single generation of an octopus.”

The crew counted 25 octopuses, though Du Preez said she has “no doubt that there were hundreds more than what we saw.”

Heidi Gartner, a DFO researcher, said that as they moved along the seafloor in more sandy locations, they also saw young octopus close to the nursery.

“It was really good evidence for us that this nursery habitat is really effective,” said Gartner.

Deep-sea octopuses represent the top of the food chain, said Du Preez. “When the top predators aren’t healthy, they actually have an effect back on the ­ecosystem.”

Du Preez said octopus living along Hesquiat slope will have an impact on global ocean ecosystems.

“If you didn’t have that nursery ground … you almost couldn’t imagine the ripple effect, if that wasn’t a safe place for the octopus,” she said. “You might not have that type of octopus anywhere along the North ­American continental slope — all five coasts — because they all come from that one nursery ground.”

Dianne Ignace lives in the small village of Heskwii in Hesquiat Harbour, and says octopuses close to the shore are a common sight for her family. “We do have some excitement with [octopus] every now and then.”

Ignace said she has been told stories by her husband and his father, George Ignace, about the rocky ­drop-off at the edge to the channel where octopuses could reside.

“Long ago, the old timers used to go down there and dig them out,” she said. “They get right in the water, and nobody does it anymore.”

They would eat them, she said.

Oftentimes, when Ignace or her family have come across an octopus, it’s in the winter. When they do find them on shore, it’s typically after they have been dropped by an eagle.

“Eagles fly over here with it, and they just lose their grip or somehow the thing wiggles free,” she said. “It drops on the flat, and a lot of times when that happens, the eagles dive down and they start eating it on the beach.

“Eagles really like to eat octopus because we’ve seen a lot of them eating them.”

Ignace said once they saw a sea otter lying on its back eating an octopus.

“It fell off a few times, too, and then the sea otter would dive under and find it again, pick it up again,” she said. “It was really interesting to watch.”

For Gartner, a love and connection to octopus can help connect people to the importance of deep-sea ­conservation.

“Seeing an animal that’s intelligent and with big eyes and living so deep, so remote, so far away from us, and yet, there’s so many elements that you can connect to — it’s just kind of special,” said Gartner. “It’s a great way to connect the deep sea to us.”

— Ha-Shilth-Sa

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