Is this a new 'Great Whale'?

October 28, 2010

You'd hardly think that in 2010, some of the biggest animals that ever existed, were still left to be discovered. We're not talking about dinosaurs but modern-day whales.

This month on Australia's north west shelf, I was lucky enough to guide an enthusiastic team of amateur birders and wildlife enthusiasts into what I believe is one of the richest marine areas of the world. Amongst the eight species of cetacean we saw on thie Peregrine Bird Tours trip (which also included Australia's only endemic dolphin, Australian Snubfin Dolphin ) were a number of whales different to anything I've ever seen before.

Between 10-14m long and with newborn calves, these whales are like a cross between the rather subtly marked Bryde's Whales and the heavily marked Fin Whales. Of course, they were too small and the wrong shape for Fin Whales but they had that white lower jaw only on the right hand side, which until recently was a unique Fin Whale character - until that is, Ben Kahn found odd whales in Indonesia with this feature ... and in 2003, Japanese whalers described "Omura's Whale", as a 'pygmy' form of Bryde's.

Our whales were feeding voraciously over deep reefs and shoals in only about 50m of water, with a supporting cast of Wilson's Storm Petrels and Spotted Sea-snakes.

On the face of it, this would seem to be a new whale for Australia and quite possibly an undescribed 'taxon' - that is, a type of whale that is unknown ... maybe a species or a subspecies.

What is for certain is that this animal occurs in an area undergoing rapid expansion for oil and gas and where last years well-head blow-out indundated tens of thousands of square kilometres of ocean with oil. This was a lesser-known incident over-shadowed by the BP disaster in the Gulf of Mexico and was surveyed by WWF .

What's faintly amusing about this story is that the discovery was made by a group of sea-going 'grey nomads' (as they are referred to in Australia). This is despite investment into 'research' on the northwest shelf by industry with a commercial interest in the area. While I mention it, the group also found a population of a new seabird for Australia: Arabian Shearwater . It just goes to show, how important communities can be in helping understand and manage our planet's ecosystem.

For further information, contact Simon Mustoe by leaving a comment on any of the images.


[Approximate location only shown]

The sightings were discontinuously distributed along a transect about 40 miles long, in water varying in depth between 50-70m. The whales were always in association with strong surface patterning, surface algal growth, some seabirds and sea snakes. This suggested that their distribution was determined to some extent by the presence of sub-surface reefs, currents and upwelling. The animals were not seen singly. Up to three or four animals would be seen together and at least two were with small calves. 

Behaviour was fairly consistent for all pods encountered. They would break the surface rapidly for short breaths, diving for periods of 2-5 minutes, presumably while feeding. Sometimes fluke-prints would be visible every half a minute or so. About every 20 minutes, they would surface strongly two to three times, when the blow would become audible and visible. The rostrum often broke the surface, permitting clear views of the splashguards, lower jaw, rostral ridges, back and dorsal fin.

The animals were clearly far too large and wrongly-marked for Minke Whales but too small for Fin Whales. Sei Whale is the closest in size but lacks the white right jaw and has a distinct peaked rostrum and long drooping snout. These animals had a very flat-topped rostrum.

The whales were obviously Bryde's-types. The dorsal fin was relatively small compared to body-size and although variable, always strongly hooked. The whales were however very large. Based on the length of our vessel, we estimated them to be between 10-14m long – they looked larger in size to Bryde's Whales I have seen on the Great Barrier Reef (GBR). The dorsal fin usually appeared a couple of seconds after the blow had dissipated, unlike the simultaneous appearance on animals from the GBR. 

There were also no obvious pale markings along the flanks, though the water was relatively turbid and nothing below the surface could be seen. Nevertheless, Bryde's Whales usually show some bicolouration when they arch up to dive. The flanks are usually slightly paler, merging in coarse mottling into the dark back. These animals were completely different, being instead, quite dark all over (reminiscent of Sei Whale) with swirling patterns more reminiscent of one of the large baleen whales. 

Compared to Bryde's Whales on the Great Barrier Reef, these whales were much more strongly patterned, longer in body and with patterning more typical of a large baleen whale.

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Is this a new 'Great Whale'?

Comments

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Kris D. on March 8, 2011 about Is this a new 'Great Whale'?

Well, your lower estimate (10 m) is smaller than the largest (11.5 m) of the females taken by Japanese whalers off the Solomon Islands in 1976. Also, as Pitman noted, six specimens (I don’t know what the lengths were for the two caught off the Cocos-Keeling Islands in 1978) isn’t very much to go by to determine maximum length in a species. Perhaps they may be a larger subspecies of B. omurai? I’m a bit confused about whether we’re talking about the same sample or not. Pitman contributed to the source I cited (I doubt he wrote the section on B. omurai, though). The photo shows what appears to be B. omurai, and gives Kahn as the source for the photo. Perhaps it was a mistake by Jefferson et al. (2008)? Well, I hope you do get some more sightings of whatever this subspecies/species is, although morphologically they look exactly like B. omurai, just a tad bigger (if your 14 m estimate is correct, that is). Good luck on your next trips.

Simon Mustoe on March 8, 2011 about Is this a new 'Great Whale'?

Kris, it was mostly size .. here's part of a response from Bob Pitman (noting that he admitted having less expertise on baleen whales than toothed whales) - as you say, they appear too long for omurai. So I am not quite sure what to say here - they look more like fin whales to me than anything else, but I take you at your word that they aren't like any fin whales you have seen before. I think there that are likely undiscovered taxa of rorquals around, subspecies or maybe even species, that have yet to be described and these could be 'dwarf fin whales', for example. I think it would be worthwhile to collect some tissue samples from these animals and see what you have. They look a too big for omurai to me but then there haven't been many omurai measured. - ..and the message from Benjamin Kahn (I presume the same DNA samples you are talking about) - In 2005 we did biopsy a similar medium baleen whale in Komodo National Park, and worked with Dr. Andy Dizon molecular ecology lab to get an genetic ID on top of our detailed field data - these whales were regulars. The biopsied whale was ID'ed as a pygmy Bryde's whale. I assume you are aware of the limited verifications on Omurai's after it was described, and the unresolved status of the whole Bryde-Sei complex. -

Kris D. on March 8, 2011 about Is this a new 'Great Whale'?

What are the "few things that don't fit"?

Kris D. on March 8, 2011 about Is this a new 'Great Whale'?

The size (10-14 m), the hooked dorsal fin, the asymmetrical coloration on the right jaw and face, and the chevron pattern are diagnostic of Omura's whale. As you said, they're not Bryde's and they're not fins, nor could they be sei whales. I'm very confident on the ID. Jefferson et al. (2008, p. 58) has a photo caption of an individual seen off Komodo National Park which was said to have been positively ID'd based on genetic profiling. Believe me, there's no other species the whales you sighted could be.

Wildiaries Admin on March 8, 2011 about Is this a new 'Great Whale'?

Kris, You're one of the few people I have heard from who'd recognise this as a possibility. I did send the images around authorities including people who've done DNA work on Brydes-types off Indonesia and Hawaii. Although on the face of it, these look like Omura's, there are a few things that don't fit. There's little way to know for sure without going out there. Problem is, as far as I know, Omura's has never been confirmed at sea from DNA and the relationship between this and other Bryde's-types is still somewhat questionable. The illlustrations in the guides (done by a friend of mine) are based on very limited material. I'm hoping to see them again later this year. who knows, maybe we can get better pictures.

Kris D. on March 7, 2011 about Is this a new 'Great Whale'?

I'm afraid the whales you saw are not an "undescribed taxon", nor do they require a new name. Looking at you're photos and reading your description of their estimated size, they appear to be Omura's whale (Balaenoptera omurai), which you briefly mentioned in your text. They have a hooked dorsal fin and white right lower jaw characteristic of Omura's whales (see Jefferson et al. 2008, Marine Mammals of the World).

David D. on November 4, 2010 about Is this a new 'Great Whale'?

Simon...This is quite a find and I totally agree. These animals, although baring some resemblence to "other" rorquals do appear quite unique. I'll be staying tuned for further information when it comes to hand. Perhaps we could be getting close to replacing the old "Unidentified Large Whale" with a species name??? Well done!!!

Reiner R. on November 1, 2010 about Is this a new 'Great Whale'?

Sounds like something interesting... cool when that happens.

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Simon Mustoe