It's the middle of the annual winter whale migration season, with both the east and west coastlines of Australia abuzz with acrobatic displays and stunning images of adult whales and their young.

Key points: Southern right whales have no fins on their backs. They have patches of roughened skin that can look like "a pile of stones" on their heads

Southern right whales have no fins on their backs. They have patches of roughened skin that can look like "a pile of stones" on their heads Humpback whales can be distinguished by their small dorsal fin and long pectoral flippers, and they show their tail flukes more often

Humpback whales can be distinguished by their small dorsal fin and long pectoral flippers, and they show their tail flukes more often Blue whales are the biggest. They are actually grey, but appear aqua under water. Seeing one is considered to be a very special occasion

Identifying different species of whales might be a bit of a challenge, but knowing whether it's a humpback, southern right or blue whale cruising past can actually help scientists with important marine research.

Which one is which?

Humpback, southern right and blue whales make their way along Australia's coastlines at different times of the year and can be spotted from vantage points in places like the coastal town of Albany in southern WA.

Kirsty Alexander, an Albany-based marine biologist who coordinates a citizen science project studying cetaceans or marine mammals, is an expert on identifying different species of whales.

Marine biologist Kirsty Alexander has tips for identifying different whale species. ( ABC Great Southern: Ellie Honeybone )

"When we are looking after any kind of animal species or habitat, we can't do that well if we don't know anything about the animal," she said.

"Knowing where the whales are, what they are doing and how much time they are spending there can tell us a lot about the species themselves.

"We are very lucky in that all of our whales do have some really obvious features that do separate them quite easily once you know what to look for."

Spotting a southern right

Southern right whales can be found on Australia's east, west and southern coastlines and migrate between summer feeding grounds in the Southern Ocean.

Mrs Alexander said this species was often spotted close to coastal communities such as Albany because they were seeking out the shallow, protected bays along the coast to breed.

"Because they come in so close, we do get a really good look," she said.

Smile for the camera! Southern right whales have unique skin patterns. ( Supplied: Kirsty Alexander )

"I guess their best feature, to quote my little daughter, is if you see a whale that looks like it has got a pile of stones on its head, then you are actually looking at a southern right whale.

"Those are actually patches of roughened, keratinised skin called callosities and those patterns are different for every single whale."

The callosities on the skin of southern right whales are unique to each individual. ( Supplied: Kirsty Alexander )

This species also does not have a fin of any kind on its back.

"They are really quite big too," Mrs Alexander said.

"Those guys are the most broad and fattest of our whales."

Hang on a minute, that one's a humpback

During the winter months, humpback whales migrate northwards along Australia's east and west coasts to their calving grounds and from September they head back down to feed near Antarctica.

"They are most easily identified if you actually see them surface and dive again," Mrs Alexander said.

Humpback whales have a distinctive dorsal fin on their backs. ( ABC Great Southern: Ellie Honeybone )

"They do actually have a very distinct hump on their back that has a small, stubby dorsal fin on top and very long pectoral flippers on the side.

"These flippers are a fairly significant feature and they slap those on the surface for communication."

Humpbacks show their tail flukes more often than other whale species.

"It's actually the underside of those flukes that identifies those whales as humpbacks and also as individuals," Mrs Alexander said.

"Underneath there is a pattern of black and white and that is as unique to that animal as our fingerprint is to us."

The underside of a humpback fluke has a black and white pattern unique to each animal. ( Supplied: Kirsty Alexander )

The really big one

The blue whale — the largest animal that ever lived — can be spotted along Australia's southern coastline from November to June.

Mrs Alexander said spotting a blue whale was a very special occasion.

"Those guys tend to have a very tall, bushy blow or spray, which gets our local whale watch operators pretty excited if they see that," she said.

"Those guys are actually not blue at all, they are a beautiful steely grey colour.

Blue whales are actually grey, but appear blue when submerged under water. ( Supplied: Ningaloo Aviation )

"When they are actually slightly submerged under the water they are that beautiful aqua colour that we see.

"They have a tiny dorsal fin as well, about two thirds of the way down their back, and a very mottled pattern on their side."

Blue whales can grow up to 30 metres long with the pygmy blue whale species reaching about 25m in length.

Mrs Alexander said identifying a blue whale was easy as they were "just so big".

They were slender and streamlined compared to southern rights and humpbacks, she said.

A single ridge on the top of their head leads back to a blowhole with a prominent 'splashguard'.

Humpbacks and southern right whales also have a unique blow or spray but Mrs Alexander said she did not rely on that feature as it was often too windy.

"Southern rights have a fairly distinct V shape to the blow but it is best to actually see a part of the animal's body."

Citizen science is vital for research

Mrs Alexander said anyone could contribute to whale research once they knew what to look for.

"If you are a researcher, whales are pretty mobile and for these guys it is nothing to travel 6,000 kilometres one way when migrating," she said.

"So it is very difficult to be able to find them and to be able to be with them for long enough to study [the whales].

"But anybody who knows what to look for can be part of that research and knowing what you are looking at should also enhance people's enjoyment of their sightings."

Usually when a whale is spotted, someone is around with a camera and Mrs Alexander said good photos were important.

"If we have good photos of the identifying features of the animals, that can actually be contributed to research across a range of databases so that we do actually know more about what we have," she said.

"Even just knowing the numbers and how they are going in terms of their population [is valuable], given that it is not actually that long ago when we ceased whaling in this part of the world.

"If we know more about the whales, what they are doing here and which areas are most important to them for activities like calving and breeding, then we have a much better chance of making good decisions about our own activities and making sure the whales are still here for the future."