The Bryde's whale has been playing tricks on us ever since its discovery. For the past hundred years, the scientific description of the elusive marine mammal has remained blurry, an outline drawn in pencil that still awaits its final inking. Today, scientists believe that what was originally thought to be a single species actually represents a group of several closely related whales: a "species complex". But working out how many different members should claim their place among the Bryde's bunch has been – well, a whale-sized challenge.

This is why a complete Bryde's whale specimen that washed up in Namibia recently has local scientists so excited.

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The large whale carcass, which washed ashore in Swakopmund in November, could be the key to solving a century-old mystery. Image: The Namibian Dolphin Project

The animal in question washed ashore last month in the city of Swakopmund, where the Namib Desert spills into the sandy beaches of the Atlantic. A Bryde's whale in southern Africa is not an unusual find – it's here that scientists first learned of the whale's existence – but several unique features in this particular specimen made local researchers sit up and take notice.

For a start, the animal was longer than the Bryde's whales usually encountered in coastal waters, which measure under 14 metres. What's more, its remains were dotted with bites from cookiecutter sharks. These fearsomely toothy fish inhabit the depths of the open ocean, so the telltale marks they'd left behind on the Namibian specimen were an important clue: this whale was a voyager from afar. 

Scientists know that two populations of Bryde's whales cruise the southern African coastline: one inshore and one offshore. The latter group remains poorly studied and its enigmatic representatives are rarely seen – but it's also where scientists must look for the missing piece of the Bryde's whale puzzle, a piece that has been lost for over a hundred years.

A mighty mixup

By the turn of the 20th century, the modern whaling industry had spread from Norway to South African shores. When the fleet returned home after the first season abroad in 1909, several of the more seasoned captains spoke of a large baleen whale that lived well outside known habitat. Their exotic accounts piqued the interest of Norwegian scientist Ørjan Olsen.

During his time at the whaling stations in South Africa, Olsen was able to examine 12 Bryde's whale specimens. Image: Biodiversity Heritage Library

Seeing a rare opportunity for scientific discovery, Olsen secured funding for a research expedition from the Norwegian consul to South Africa, John Bryde, who had helped set up the first whaling station in Durban, along the country's eastern coast. Data from this part of the world was sparse, and Olsen knew that the whalers' all-hands-on-deck approach to whale capture could be used to nudge science forward.

"It is not surprising that the bigger whales ... have remained unknown," Olsen wrote of the region. "When at rare intervals one of the whales stranded on the South Africa coast, if it was not at once eaten by sharks, it was, as a rule, quickly destroyed by the warm climate and heavy sea breaking on the beach." 

During his stay at whaling stations in both Durban and Saldanha Bay on the opposite coast, Oslen was able to examine 12 whale specimens. Based on that research, he described the very first Bryde's whale in 1913, naming his find Balaenoptera brydei, after the man who backed his expedition. The species-sleuthing triumph had one fatal flaw, however: Olsen had unknowingly mixed features from both the inshore and offshore whale populations.

The whale he described was sometimes covered in "whitish-grey oblong spots" – cookiecutter shark bites like those seen on the Namibia carcass – suggesting an animal that spent its time in deeper habitat. Yet he also made note that his whale was abundant in bays and other nearshore inlets, feasting on coastal fish, small sharks and even penguins. Measurements of the animal's anatomy were a mishmash, too.

Today, more than a century later, scientists are still trying to set that mishmash straight. 

"The species was never properly described," explains Dr Gwenith Penry, a postdoctoral researcher with the Coastal and Marine Research Institute at South Africa's Nelson Mandela University. As the principal investigator of the Southern African Bryde's Whale Project, Penry, along with a group of colleagues, has now taken up the description challenge afresh.

Olsen's mistakes eventually led to his scientific name for the whale being cast aside, and today, all members of the Bryde's complex are gathered under another Latin label – Balaenoptera edeni  even though some of them probably don't belong there. 

Some of the whales might represent different "forms" or subspecies. For example, because many large filter-feeding whales – like blue, sei and fin whales – spend much of their lives in the open ocean, scientists believe the inshore Bryde's whales actually evolved from their offshore kin, only adapting to life in shallower water over time. 

Before such descendants or offshoot populations can be officially recognised, however, the "original" Bryde's whale must be revealed in its true form.

The scientific name for any species is anchored to a "type" specimen – one whose anatomy has been carefully documented, allowing it to serve as a reference point for assessing differences between the animal and any of its close relatives. Olsen's accidental "grafting" left a question mark in place of the Bryde's whale "type", and because his observations were made in southern Africa, the rules of scientific naming (taxonomy) dictate that any replacement also has to come from this region. 

"We need a confirmed specimen from the offshore population, none of which exist in our museums," says Penry.

That's what makes the Namibia carcass so valuable: it could represent the trunk of the Bryde's whale family tree – the one that allows us to trace out the other branches.  

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The Namibian carcass could turn out to be first complete specimen of an offshore Bryde's whale. Image: Namibian Dolphin Project
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Namibia's washed-up carcass was much longer than the Bryde's whales typically seen in coastal waters. Image: Namibian Dolphin Project

A hidden gem

It might seem extraordinary that a 15-metre animal could still elude scientists after so many decades of research, but despite their impressive bulk, offshore southern African Bryde's whales are experts at staying hidden. In fact, even after all this time, most of what we know about them comes from historical whaling data.

Any attempts to photograph or sample these creatures would be both expensive and time consuming. "You'd need a big ship and expedition to get out to see them," says Penry. "Even then, the chances [of finding one] are slim because they are so rare," she says.

The headline-grabbing nature of whale strandings might give the impression that such events are common, but in reality, most whale bodies actually sink before they come anywhere near land. Oregon State University whale biologist Dr Bruce Mate estimates that even under favourable conditions, a whale's death has to occur within ten miles of shore for there to be any chance of collecting it in the surf. 

That means if the Namibia carcass does turn out to be a representative of the offshore Bryde's whale, it will be a lucky find indeed. 

"It could represent the only specimen of an offshore southern African Bryde's whale," explains Penry. "We hope to positively identify [it] so that we can correctly describe the type specimen. That means that all other Bryde's whales around the world can be compared to this one to determine if we have multiple different subspecies or populations."

Exactly what caused this particular animal to wash ashore remains a mystery, but a large dent in the whale's body could indicate that it was struck by a ship. 

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The Namibian specimen may have died after colliding with a ship. Image: Namibian Dolphin Project

A Bryde's by any other name

So much wrangling over whale names might seem like a case of much ado about nothing – and even the experts working on such scientific descriptions find the process crazy-making at times – but there's method behind the madness.

To this day, many official species protections are awarded only if a group of animals has its established spot on the tree of life, so finding a place for the Bryde's whale is crucial for its future conservation. 

Small groups of coastal Bryde's whales are being discovered in habitats all around the globe, and many are at risk of disappearing before scientists can put proper conservation strategies in place. 

John Ososky, osteo-preparations specialist and vertebrate zoology collections manager at the Smithsonian Museum of Natural History, who is not involved with the South African research, notes that a unique population was recently discovered off the Gulf of Mexico, and another has been located in the waters off Japan. 

"There is still much debate internationally over what the criteria are for identifying a species within this complex," says Ososky. 

It's estimated that fewer than a hundred Gulf of Mexico Bryde's whales are in existence, and the group is already under threat from oil and gas drilling. Given these small numbers, the animals are also vulnerable to genetic bottlenecking, and may be less resilient to environmental changes. 

The National Oceanic and Atmospheric Administration (NOAA) has proposed that the Gulf of Mexico whales be offered an endangered species listing, and while the animals may be granted some protections as a unique and distinct "chunk" of the Bryde's complex, no official subspecies recognition can be finalised at this point.

"It is probable that the Gulf of Mexico population has a similar relationship level as our inshore southern Africa population does to the offshore type," suggests Penry.

Back in October 2016, Dr Penry was able to examine another Bryde’s whale carcass, which washed up along South Africa's eastern coast.

With the taxonomy in a tangle, granting blanket protections over the entire Bryde's complex might seem like an easier solution. Targeted conservation strategies would be more effective, however. That's because human activity – from boat traffic to commercial fishing – likely impacts each of these whale groups differently. 

Africa's inshore and offshore Bryde's whales, for example, lead very distinctive lifestyles. The shallow-water whales don't venture beyond the continental shelf, they don't migrate, and they feed mostly on small baitfish like sardines and anchovies. The offshore whales, meanwhile, eat small crustaceans and plankton. They also make return trips to and from the equator, and rarely show up in waters shallower than 400 metres.

Genetic testing can give scientists a pretty good idea of how these groups relate to one another, but more samples from Bryde's whales around the world are needed before we can confidently rely on the genetics alone. And being able to compare a whale that inhabits the Gulf of Mexico, or a shallow-water African cousin, to an accurate Bryde's whale "type" for the species will be a step in the right direction.

Working backwards

The task of identifying and describing the Namibia carcass will take several years, but with the help of the country's Ministry of Fisheries, the Luderitz Museum and the Namibian Dolphin Project, the tedious process of securing, sampling and disassembling the lengthy leviathan has already begun.

While there are no full specimens to compare it to, previous research has left a trail of clues that could prove helpful along the way. In the past, Penry has run DNA analysis on a piece of whale skin recovered from another washed-up carcass, featuring the same telltale cookiecutter scars. There's also a chance that a skeleton at a museum in Stockholm (which was imported from South Africa) might be that of an offshore Bryde's whale. 

Over the coming months, the team will perform a detailed analysis of samples taken from the Namibia carcass. They'll also conduct a full overview of the skeleton, paying particular attention to the skull – one of the key traits in differentiating these animals. If the features prove different enough from more readily accessible coastal Bryde's whale specimens, this century-old puzzle might finally be solved.

"Basically, we're working backwards," says Penry.

And in the case of the Bryde's whale, the only way forward lies a few steps back.