Mary Gardner
Like others that day at the Cape Byron lighthouse, David Bryant saw this small whale ride a wave. Skilled photographer that he is, he had his camera to the ready and took this photo that has flashed its way through media around the world.
Some specialists identify this as a dwarf minke whale Balaenoptera acutorostrata subspecies. Or a Bryde’s Balaenoptera brydei. Or even an Omura’s whale Balaenoptera omurai.
In the foreground of the wave are small fish bursting through the water. Likely, this surf rider was also interested in a feed.
Any of the dwarf minkes, Bryde’s or Omura’s whales are some of the smallest of the group of baleen whales. These include the blue, humpback, fin, sei, and several others. The smaller species are not clearly distinguished or well understood.
The Omura’s was only identified as recently as 2003. All these whales have mouths full of stiff baleen plates. Such plates are made of keratin, the same protein that makles hair, fingernails, and hooves.
Baleen whales all feed by lunging into schools of small fish and krill
Baleen whales all feed by lunging into schools of small fish and krill. They gulp, taking up great quantities of seawater. Strings of nerves in the pleats of their throats coordinate the large expansion of their mouths. As the mouths close, seawater is forced through the plates. The fish remain trapped behind the baleen.
What if the photograph is of a dwarf minke? In 1998, this subspecies was identified as distinct from the larger minke group. Each adult averages ten metres in length and weigh some 9,200 kilograms. In the Southern Hemisphere they appear to migrate each year from Antarctica to the tropics. They are more often travelling the open ocean than the coasts.
As dwarf minkes do not have the blubber reserves of larger whales such as the humpbacks, they feed year round. While they travel to the tropics, they often hunt across the seas for small fish especially lanternfish (family Myctophidae).
Each lanternfish is only about 12–15 centimetres in length. But as part of some two hundred different species, they total 65 per cent of the weight of all fish in the twilight and midnight zones (200 to 3,000 metres).
Under the cover of each night, these fish migrate to the surface. They follow their prey, the great schools of plankton who also migrate in the dark. Individuals of each species signal each other, flashing their own patterns of bio-luminescence. In turn, they are food for tuna, sharks, squids, sea birds, and marine mammals including the dwarf minkes.
Each winter, some dwarf minkes frequent an area in the north of the Great Barrier Reef
Each winter, some dwarf minkes frequent an area in the north of the Great Barrier Reef. Here they socialise with each other and the peculiar snorkelling humans who also gather and gawk. The whales mate, have their babies, and sing songs.
Recently, the dwarf minkes were identified as the sources of mysterious sounds recorded at 1,000 metres depth near the Mariana Trench.
Known as the ‘Western Pacific biotwang’, each call is 3.5 seconds long, with frequencies ranging from 38 to 8,000 Hertz. The call finishes with a blast similar to a ‘Star Wars’ sound effect.
If the photograph is of a Bryde’s or Omaru whale, the creature belongs to a larger ‘Bryde complex’. These are five or six similar but distinct species that are even more poorly known than are dwarf minkes. They tend to live in tropical or temperate waters; the larger ones farther out to sea. They are heard making ‘moans’, sometimes short, sometimes long.
Commercial and scientific whaling only concentrated on hunting these smaller whales after the larger ones became scarce. Tens of thousands were known to be killed: likely an underestimate. Some are still hunted. Equally problematic, the krill and lanternfish on which they rely are targeted by large industrial fishing vessels.
But I look at the other photographs David took of that lone whale. Joy sparkles on the waves even though sure knowledge is fragmentary. I remember a line from the poem of Joy Harjo, first Native American Poet Laureate of the United States: ‘give it back with gratitude… help the next person find their way’.
What little I can say here about this whale might prompt a youngster to become that biologist who may, in time, explain a little more.
Wow! So great this image was captured! Good one David!