After many failed attempts, a false killer whale calf rescued near Tofino, B.C., earlier this month has reached a milestone and has started nursing from a bottle, according to staff at the Vancouver Aquarium Marine Mammal Rescue Centre.

Head veterinarian Martin Haulena said the fact the calf is now suckling is a great sign of improvement, and the male calf has been slowly increasing its strength, buoyancy and co-ordination.

"He will need to get better at feeding from the bottle over the next few days in order for that to be the only way we provide nutrition, but this is a great start," said Haulena.

False killer whales (Pseudorca crassidens) are a species of oceanic dolphins, which are distinct from the killer whale (Orcinus orca). They are only rarely sighted in B.C. waters.

Like some types of killer whales, they live in the open ocean around the world and hunt other types of marine mammals.

The calf at the Vancouver aquarium had previously been feeding exclusively from a tube, but aquarium staff say bottle feeding means the calf can now be fed more regularly, and with less handling.

Staff at the aquarium shot a video late Tuesday night of senior vice-president Clint Wright coaxing the calf to nurse from a bottle designed specifically for it by PhD student Amelia MacRae.

False killer whale improving0:37

Aquarium controversy

The calf was rescued by aquarium staff and officials from the Department of Fisheries and Oceans from Chesterman Beach on the West Coast of Vancouver Island and transported to the rescue centre on July 10.

False Killer Whale rescue

The false killer whale calf, a species of dolphin rarely seen off the coast of B.C., was rescued by scientists from the Vancouver Aquarium and DFO on July 10. (Neil Fisher/Vancouver Aquarium)

The centre rescues stranded marine mammals and rehabilitates them for release into their natural habitat, but its connection with the Vancouver aquarium makes it controversial.

When he spoke the day after the rescue, Haulena said his focus was on saving the dolphin and not on the controversy surround the keeping of cetaceans in captivity.

"It's often considered to be a tropical or sub-tropical species. So there is some interesting questions about why the animals are here, what they're doing here and how they migrate in response to water temperatures and climates and seasons," said Haulena.

Three groups living around the Hawaiian Islands are among the most studied populations.