Blue whales of Perth Canyon

Its been quite some time since I discovered that Blue whales (Balaenoptera musculus) visit Perth Canyon in Apr-May.  Perth canyon is approx 22kms off the coast of Fremantle and has depths of 700m-4kms!  It’s similar dimensions to the Grand canyon but of course you can’t see the scale with all that ocean on top.  The whales are coming to the canyon feeding on aggregations of krill – tiny marine shrimp, that feed a whale that can get up to 25m long!

I have always had an interest in Blue whales ever since seeing the 24m long skeleton in pride of place in the WA museum.  I have not been able to show my kids yet – but I’m excited that come 2020, it will be featured in the new building.

I volunteered to organise a WA Naturalists excursion utilising the family business Whale Watch Western Australia – the only company that visit the canyon for whale watching.  As part of my planning I checked out the company previously on a Humpback whale (Megaptera novaeangliae) tour in October off Fremantle.  I had been to the canyon once before on a pelagic bird watching tour where we had an amazing sighting of Orca (Orcinus orca).

We had planned to go a month before, but one day before the trip the boat hit a floating semi-submerged boat wreck and sheared off one of the blades on one of the props!  We had over 20 people signed up – so lots of communication as we all had to reschedule once they were able to get a replacement prop built from scratch and installed.

 

We boarded MV Steep Point just before 8am with 44 on board – 4 of us WA Nats members plus some family members.  The above photos are from my previous trip as I forgot to take new ones.  The day was perfect, not a cloud in the sky, with light easterly winds which were going to drop, no swell to talk off, and sunny & mild (~27ºC).

Leaving Fremantle

Rottnest to the East – not a common view!

We were surprised by a pair of humpbacks – an adult with a yearling calf – they were just west off Rottnest migrating North and the earliest of the season.

I saw a couple of Great crested terns (Thalasseus bergii) and then a pair of fisherman in a pretty small boat for how far out they were!

As we came to the canyon and started looking for whales we sighted some splashing a long way off, which turned out to be a few hundred Striped dolphins (Stenella coeruleoalba).  The pod was hugely energetic with many launching into the air.  Really spectacular and a new species of mammal for me.

We then headed on to the northern most part of the canyon looking for Blue whales – they tend to be found on the walls as it is thought they herd the krill using the structure.  For some time we didn’t see any whales and I must confess I thought we might be too late in the season.  But then a misty blow was seen perhaps more than a km off and we headed towards it, seeing a few more blows on the way.

Blue whale blow @ Perth canyon

We then saw the blue whales – approx 25m long – which is the same length as our boat carrying 50 people!  Another lifer species for me – two in one day!

Blue whale @ Perth Canyon

The name blue whale was first referenced in the book Moby Dick and refers to the aqua blue colour of their skin when underwater (see the aqua strip in the image below – out of the water they are a mottled grey colour.

Submerged Blue whale @ Perth Canyon

We saw 4 individual whales ranging from the 25m adult above to a yearling approx 14m long (see darker grey image bottom right below) – which is the same length as the adult humpback we saw earlier!

One interesting fact is the mottled colouration on the whales can come from healed scars from cookie-cutter sharks.  They have circular sucker mouths and teeth that take a plug of flesh – the below image shows the whale just below the dorsal fin and then a close up where you can see the wounds from the shark.

After spending a good few hours with the blues we headed for home – the sun on the water was amazing.

Just heading out of the canyon we came across another (or maybe the same) pod of striped dolphin – these were launching into the air!

We also saw a few Australasian gannets (Morus serrator) on the way back.

I highly recommend the tour company Whale Watch Western Australia – they are a family run business and really care passionately for the whales and their customers.  The day tour included all meals, drinks and also beer, cider & champagne celebrating our sightings!  Fingers crossed I might be able to arrange an Orca trip out of Bremer Bay next April – I did say they might need to include child care in their packages!

Below are some photos from the boat to give an idea of the viewing.  On the shorter tours the captains cabin is only accessible with a higher level package.

The WA Nats crew for our expedition – a shame we couldn’t get everyone on the same tour.

All in all this was a trip of a lifetime – I am already planning to take my wife and 4 year old son to see the Humpbacks come September!

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