The deep hides its secrets well. Like peering into Narnia through the crack in a wardrobe, scientists can only ever catch occasional glimpses of what goes on hundreds of metres beneath the sea; either from submersibles, remote cameras, or by studying the strange fish that turn up in commercial fishing nets. Strange fish indeed. There are animals here that resemble the fevered depictions of alien life from sci-fi movies; undoubtedly many of them have provided film directors with their inspiration. Some look as though they’ve been stitched together from the leftovers of other fish, like some kind of celestial prank. There is a fish called the blobfish that simply looks like a blob. Really.

These animals come from a high-pressure, dimly lit, and relentlessly cold environment which has produced idiosyncratic and often bizarre anatomical responses: disproportion­ately large eyes, disproportionately large teeth, feather-like fins, parrot-like beaks and biolumi­nescent lamps.

It was just such deep-sea creatures that captured the attentions of Claire Nouvian, a French photographer, film maker and author who recently joined New Zealand scientists on the research vessel Tangaroa, specifically to collect the weirdest deep-sea creatures she could get her gloves on. Injecting her creatures with formalin, she packed them into boxes, and shipped them back to Paris—a kind of contem­porary equivalent of 18th century biologists collecting novel animals from around the world for display in the museums of Europe.

“There are so few research institutes do­ing deep-sea work in the world,” says Nouvian, when asked what brought her to these parts. “Of course, New Zealand has deep waters all around it with various chains of seamounts and a tremendous diversity, so I was hoping to get a good sample of species. But the reality exceeded my wildest dreams.”

Nouvian joined NIWA staff on their annual trawl survey of the northeastern Chatham Rise in July last year. Such surveys are aimed at as­sessing orange roughy stock. Deep-sea research in New Zealand is invariably funded by, and therefore tied to, the fishing industry. But any survey trawl also hauls up creatures that swim with the orange roughy and are usually lumped together, rather disparagingly, as bycatch, but are all marvels in their own right.

Nouvian couldn’t believe her luck. After three weeks almost every weird and wonderful species on her “wish list” had been collected and preserved in formalin. “New Zealand wa­ters are biblical.”

Biologists on Tangaroa say that Nouvian’s enthusiasm managed to remind them that the strange fish they encounter every day on these surveys really are also fascinating creatures full of unsolved mysteries. Sometimes, after seeing hundreds of them, you can forget. Says NIWA scientist, Matt Dunn: “I remember one of the first trips I did and getting really excited about seeing a viperfish. Even seeing my first orange roughy was really exciting, but by the time you’ve seen 10,000…having someone like Claire on board reminds you that the animals you’re seeing really are quite exceptional.”

Taxonomists dissect these creatures look­ing for anatomical clues with a view to placing them on the tree of life—connecting them up with their genetic ancestors and classing them into specific taxa. But understanding how they behave, or trying to provide a behavioural explanation for their physical appearance, isn’t quite so simple. What is the point of that feather-like fin? Or that retractable growth jutting out from between those eyes? Why the big nose? The long face? Why, by the way, are orange roughy orange when, in the dark, all fish are grey? (Actually, biologists have only recently realised that, way beneath the waters, some orange roughy are actually white. Nobody yet has a clue yet why, because by the time they are hauled to the surface, they are orange.)

[sidebar-1]

Scientists really know more about nematodes than they do about deep-sea fish. They have to to draw most of their conclusions from netted samples with scant observation to guide their imaginations. It is prohibitively expensive to observe deep sea organisms in situ and when it is possible, it tends to be from the vantage of a large, bulky, brightly-lit and extremely intrusive observation device that has turned up in this dark and quiet place. Scientists joke that only the slow and infirm are ever caught on camera. “It’s like driving around the Serengeti in a tank with all the lights on,” says Dunn. “It’s not a very subtle way to creep up on something.”

Nouvian, fascinated by the behaviour of deep-sea creatures, has researched them for years. She probably knows as much as anyone about them and that, she says, is “practically nothing”. Take a jewel squid, for example, with its single large bulging eye and another smaller one embed­ded in its body. “There are as many suggestions about this peculiarity as there are scientists pon­dering the problem,” she says. “One of the most widespread beliefs is that it swims at a 45° angle with the big eye scanning the faintly-lit waters above it and the small eye scouting the dark waters beneath.” But it’s only speculation, she says. “The truth is that no one knows.”

Dunn’s example is a type of male chimaera, a deep-sea shark which has, he describes, a re­tractable thumb in the middle of its forehead, at the end of which is a fixture that resembles a small ball of Velcro. “That’s really weird!” he says. “Only males have it, so presumably it’s something to do with sexual reproduction. Maybe it stimulates the female or attracts her. But we really don’t know what it does with it. It’s just bizarre.”

And then there’s the anglerfish. Females of the species (featured on page 97) grow to around five or six times the size of males, and are usually found with a few males attached—fused, actu­ally – to their flank. Dunn: “So they become a parasite, a permanent fixture on her side.” And why? “The idea is that females are so few and far between that when males find them, they don’t let go”, he says. At least, that’s the idea based on the biological imperatives in which everything usually comes back to food and sex, but of course it could be the result of something else altogeth­er. “I’ve only ever seen about four or five of them but they’ve always had a male attached,” muses Dunn. “So it obviously works quite well.”

Unsurprisingly, Dunn would love to know more, or at least have the money to find out more. If he had his way he’d leave a deep-sea camera on the ocean floor for several months, so that the fish get used to it and go about their normal business in front of it. But research in New Zealand is usually aimed at assessing the impact of human behaviour on commer­cial fish species, rather than fish behaviour for fish behaviour’s sake. “It was the fisheries that stimulated the research, which is a good thing, but the focus has been on commercial species… which is why knowledge about all those other species is so slow in coming.”

Still, every trawl survey yields its surprises and adds more small details to the slowly ac­cumulating body of knowledge. This trip, for instance, involved deeper sea trawls (1700 m) which netted a number of female black slick-heads several times larger than any black slick-heads biologists had seen before, and from a depth at which no one knew they lived. Even better, two octopus caught on the survey were only the second and third of the species to have been found in New Zealand waters. Its iden­tity (probably Cirrothauma) is currently being confirmed by cephalopod expert Steve O’Shea, and this find could resolve the status of this particular and problematic taxon.

Meanwhile, Nouvian has returned to Paris, exhibiting our fish in that city’s Natural His­tory Museum. The point of it all is to shine the spotlight on the weird glory of creatures we share the world with but rarely get to see, in an effort to secure their protection. The deep is an ecosystem that has, in the past, been protected by its remoteness. Now that it is so much more accessible to commercial fishing, it is more vulnerable than it has ever been. Paraphrasing from the movie Alien, in the deep sea, no one can hear you scream. Adds Nouvian: “There aren’t any witness.”

The art of deep sea taxonomy

NIWA taxonomist Peter McMillan (below) was on Tangaroa to identify animals for a publication commissioned by the Ministry of Fisheries.

Latin names given to newly identified species are often simply descriptive. For instance, microstomus—as in Cory-phaenoides microstomus, a fish with a notably small mouth that was first identified by McMillan—translates as small (micro) and mouth (stomus). But sometimes scientists are more adventurous, as in Fiordichthys slartibartfasti. The genus name points to the fiords where the fish live, while the specific name, Slartibartfast, is a character who designed an award-winning fiord in Douglas Adams’s novel The Hitch-hiker’s Guide to the Galaxy.

To his embarrassment McMillan has had a couple of creatures named after him including a “horrible skinny
little rattail”, Coryphaenoides mcmillani (commonly known as McMillan’s whip tail), and “a soft, blobby thing”, Parmaturus mcmillani (commonly known as McMillan’s cat shark).

Often taxonomists have to speculate on why these animals look the way they do and have the appendages they have—turn to the weirdly constructed Harriotta haeckeli on page 97 to see what taxonomists are up against. And deep-sea fish all tend to be low energy creatures in various shades of grey because they live at dark depths where there isn’t much food.

Without a submersible, NIWA scientists can’t extend their investigations much beyond the few obvious conclusions drawn from observation of a trawl. “Dead fish,” says McMillan, “that’s all we have. We can look at a few influences, such as fin position, mouth shape, maybe stomach contents, but it’s very difficult. We just really don’t know.”

+ Read sidebar

Taking stock

According to Forest and Bird’s recent Best Fish Guide, we shouldn’t be having orange roughy for dinner. Unsurpris­ingly, many fishers would disagree, and they have a point. Nobody really knows with any certainty whether it is being fished sustainably, into oblivion, or something in between.

Even the Minister of Fisheries, Jim Anderton, expressed his frustration when, last year, he had to revise the quota in the absence of adequate information on stock status. He’s not the only one. “There is frustration among scientists as well, because getting the information that we need is so difficult,” says Malcolm Clark, NIWA’s deepwater fisheries principal scientist. “And technology to research them has developed more slowly than the technology to catch them.”

Tens of thousands of orange roughy annually congre­gate on the Chatham Rise to spawn, massive aggregations which, when first found in the late 1970s, launched a new fishery. That stock has now been fished to near, or possibly below, its target level of 30 per cent of its original popula­tion although there is increasing uncertainty around the accuracy of that estimate.

The Chatham Rise fishery remains the largest orange roughy fishery in the world, but the boom and bust ap­proach taken in the early 1980s resulted in most orange roughy fisheries being fished out and closed down. It was assumed back then that so many fish could only mean the species was highly productive and there’d be plenty more where they came from.

Unfortunately, this wasn’t so. Productivity is largely determined by how long a species lives and the age at which it matures. Orange roughy grow to be very old, some­where, it is believed, between 100 and 150 years. When this was first mooted in the mid-1990s many biologists wouldn’t have it, but radiometric techniques and international research has all pointed to the same conclusion. “There is still a bit of cynicism,” says NIWA scientist Di Tracey. “But we are confident that we’ve got the age right. I’ve aged one to be 160 years old.”

That orange roughy is so long-lived is one of the reasons it is so difficult and expensive to age the fish with any pre­cision, which affects scientists’ ability to assess the com­position of the population and therefore the amount that should be commercially harvested.

One way of aging a fish is by counting the rings in the small bones found in fish ears, known as otoliths, akin to rings in a tree trunk. But while tree rings clearly mark the tree’s annual growth, it’s less clear what the rings in an orange roughy represent. Moreover, in a mature fish the otolith has so many rings it’s hard to distinguish one from another. “The otoliths bend and warp and the lines are really close together,” says Ministry of Fisheries chief sci­entist, Pamela Mace. “It’s hard to know which part of the otolith to read.”

Orange roughy has many characteristics that defy scien­tific analysis: it lives a kilometre beneath the ocean, ruling out many common assessment techniques such as tagging. (By the time an orange roughy is hauled to the surface to be tagged, the change in pressure will have turned its insides into soup—it’s not going to be swimming anywhere.)

It’s also a fish that is difficult to track acoustically as its swim bladder is wax-filled rather than gas-filled—bouncing sound poorly. While an echo sounder image may show up a mass that scientists think represents a congregation of orange roughy, they can’t be sure how much of the mass is roughy, and how much is something else.

Fortunately, this is one area where technology is advanc­ing. NIWA scientists on last year’s trawl survey worked with Australian scientists to test-drive deep-sea technology that combines acoustic techniques with video photography; sci­entists at least now know exactly what the acoustic signal of an orange roughy looks like.

But that’s not the end of it. One of the reasons Anderton was frustrated by last year’s assessment was that Ministry scientists have concluded that the scientific model they have been using to make stock predictions is unreliable and should be abandoned. According to the model, the population of orange roughy should be increasing substantially, but there’s little evidence to show that it is. “The model isn’t working,” says the Ministry’s Pamela Mace, “because it assumes a level of recruitment that isn’t happening.”

Recruitment is the scientific term for the number of younger fish coming into the population. “It could be okay, but when you have a fishery, you are reliant on recruitment which we’re not seeing, and we could be doing a lot of dam­age,” says NIWA scientist Matt Dunn. “That’s the concern… we need to know where those young fish are.” While there is clearly need for further investigation, scientists and the in­dustry are in something of a Catch 22 situation—as the catch is reduced so is the money available for research.

Whether or not we should be eating it for dinner depends on who you talk to. Says NIWA’s Di Tracey, “I might when we’re out on a survey, but I prefer it marinat­ed, otherwise I find it kind of bland.”

+ Read sidebar