First Marine Fish Declared Extinct. Mass extinction? What Mass Extinction?

I was rather miffed with myself to have completely missed an important but sad conservation biology milestone back in March this year when the IUCN Redlist of Threatened Species was updated to list the smooth handfish Sympterichthys unipennis as officially extinct. The milestone got a bit of coverage in the news but given the nature of news cycles these days it’s sort of understandable that a database updating to declare an obscure and not especially photogenic animal extinct, a fish no less, got a bit buried. But why was this particular bit of news such a landmark? The listing of Sympterichthys unipennis as extinct by the IUCN is the first marine bony fish to be declared extinct in modern times. Now, that needs a bit of unpacking. There’s a bit of weaselling there to turn it into a more notable fact but given how we’re inundated with information – about biodiversity loss, changes we should all be making to benefit nature – how is it only now that the first (marine, modern etc. etc.) fish is being declared extinct? Have scientists been alarmist all this time? One extinct fish out of the tens of thousands of living species doesn’t seem too bad, does it? Surely you’d expect more if we are in the midsts of the sixth mass extinction?

Let’s unpick what this status change means and delve into a topic that genuinely keeps me up at night: how do we know a species is extinct? Hopefully this will help clarify why this is an important milestone and why it absolutely doesn’t mean that worrying claims about biodiversity loss are overly cautious or unwarranted.

Reconstructing the announcement of the news of the smooth handfish’s extinction (status) and it seems that there were a few tweets in March starting with this one from the Handfish Conservation Project but that science news networks didn’t really pick it up until July including Scientific American [paywalled], LiveScience and err a cartoon in the Guardian. I don’t know why there was the delay and I haven’t been able to find a press release that would explain the sudden interest a few months after the IUCN Red List update. I can’t help but think that if it were a mammal or bird more would have been made of it or perhaps there are too many caveats needed in order to squeeze this news into a nice clickable headline. But let’s get back to why this is so significant.

First Extinct Marine Bony Fish

From that first tweet, Sympterichthys unipennis was described as the first ever marine bony fish to be listed as #extinct. Later coverage added words to the effect ‘in recent times’. Unpacking each part of this fact. It’s not the first fish to go extinct, you can easily check the IUCN Red List yourself to see that there are currently 65 species listed as globally extinct and 10 further species listed as extinct in the wild. However, filter out all the non-marine species and we’re left with two extinct fish species, the smooth handfish and the New Zealand Grayling Prototroctes oxyrhynchus which looks to be erroneously listed as marine on the database aside from one reference to the fact that this species is amphidromous (they spend their life in marine and freshwater environments). The New Zealand Grayling was listed as extinct in 2014 but hasn’t been reliably seen since the 1920s. So I think it’s in this sense that ‘modern’ extinction is used to filter out the New Zealand Grayling. So we could contest the fact that the smooth handfish is the first marine fish to be declared extinct, I wouldn’t be surprised if there were a few other contenders too but at the moment they aren’t obvious from the Red List. To my mind this doesn’t change the announcement much: second rather than first perhaps takes away from the ‘newsworthiness’ of it but it’s still surprising that only two marine fish species are listed as extinct when we’re constantly reminded of how fragile and exploited our marine resources are.  

Story Of A Species

So what’s the story of the smooth handfish? Again, thanks to the information highway of the Internet and the IUCN Red List there’s a nice summary on the relevant species page. The smooth handfish is known from a single specimen collected in 1802 and hasn’t been seen since – with the important rider that extensive surveys in the intervening 200 years have determined. We’ll come back to this later. So perhaps this is why this announcement didn’t make the headlines as much as I’d initially expected when finding out about this species, it’s the first (second) marine fish to have its status changed on the IUCN Red List recently to extinct but could have gone extinct at any time between 1802 and recently. It’s just that scientists who were updating the information about conservation status for the whole of the handfish group Brachionichthyidae seem to have decided to call it for this particular species, hence the update and announcement.

Who Decides A Species Is Extinct? 

I’ll likely be using the example of the smooth handfish in my lecturing on conservation biology (normally with reference to museum collection use) as a nice example of sometimes the lengths that need to be gone to to change the IUCN status of a species and it’s an important lesson I think. First though let’s take a look at what the IUCN is and why they have such an important role and are the ones to list or ‘declare’ species extinct.

The International Union for Conservation of Nature (IUCN) is a really important membership union of government and civil society organisations that works internationally to conserve nature and work towards sustainable development. It’s one of the many influential international organisations formed in the wake of the Second World War with lofty goals to leverage international expertise, in the IUCN’s case, to focus on conservation work and more lately sustainability and development. Without wanting to go into the nitty-gritty of the organisation’s history and the scope of its work, one of the things it has done since the 1960s is publish the International Union for Conservation of Nature’s Red List of Threatened Species, widely known as the ‘Red List’ which is, to date, humanity’s best effort at corralling basic information about species as well as set an international standard for assessing species’ status against a number of critical indicators. It’s under the IUCN Red List categories that species can be assessed at regional, national, continental and international levels and that information is key in informing policy making, species protection which in theory spills out into legislation relating to land use, recreation, aquaculture, agriculture, etc. Although a lot of rich information is collated for each species, perhaps the Red List is best known for the categories assigned as a quick snapshot of how healthy a species is. Whenever you see reference to a species being vulnerable, endangered, critically endangered etc. this is more often than not a reference to that species’ IUCN Red List category (there are many many other organisations with different systems for categorising species; a blog post for another time). This framework and categories can also be used at every regional level so sometimes you may read that a species is regionally extinct or nationally vulnerable despite its global listing being a different category (negotiating these databases and lists is no mean feat). The compilation of the Red List is a phenomenal endeavour that perhaps isn’t celebrated enough, however, the task at hand is likely never to be completed. The Red List has gone through significant changes through the years but at the time of writing just 120,000 species out of a ballpark 1.5 million have been assessed. Of those, 17,539 species are listed as data deficient i.e. there isn’t enough information known to establish an accurate category to assign to a species. There are biases in the groups which have and haven’t been assessed and of course assessments of an entire species status should never be static, perhaps with the exception of extinction. Ideally every species would have an assessment and these assessments would be reviewed periodically by primary evidence from catch data, field surveys, etc. There are specialist international groups of experts who periodically review specific groups of organisms or push to update specific species’ categories. So in this sense, it’s experts using the IUCN framework that decide to list species as extinct etc. But…

Extinct Until Proven Otherwise? 

The ‘existence’ status of any particular species is only as good as the last authenticated account, record or specimen of that particular species and here’s where it gets scary. We’re nowhere near nor will we ever get to a point where we’ll even have a list of all the species currently living on Earth. From bacteria that live at the very bottom of the ocean to nematodes living in the soil in your back garden it’d require a dedicated army of expert biologists to even stand a chance of identifying them all, let alone give an assessment of how that species is faring within a county let alone country let alone globally. I mentioned above that last authenticated accounts of organisms are important and this is because identifications can be changed, species are sometimes split and original identifiers get it wrong. Recorded observations, photographs and satellite imaging can be used but are difficult to authenticate depending on the species. Many organisms can’t be identified from gross morphology alone. Unfortunately, there is no big list of ‘last authenticated recorded’ instance for most species. These data points may be an uncatalogued museum specimen (here’s why that happens, I will finish the series I swear), data awaiting publication or survey trawls requiring expert identification.

Another phenomenal co-operative internationally supported resource looking to make some of this information available is the Global Biodiversity Information Facility (GBIF). GBIF pulls together information about biodiversity with the goal that eventually, anybody at a click of a button can see the plotted distribution data of any particular species. GBIF contains an eye watering 1,584,649,799 occurrence records. That’s information from survey data, literature records, museum specimens and living specimens (to name a few examples of occurrence records) pulled from a whole series of biodiversity data providers. However, it’s a constantly growing resource and there are still many datasets which need leveraging. Sadly it’s not as simple as searching a taxon (try it yourself to see what information is there) and finding the last dated record as the most accurate record of that species but like the smooth handfish, there are many many species which haven’t been recorded for tens or hundreds of years. I have a few colleagues who keep lists of species not seen for tens or hundreds of years, periodically making targeted surveys to try to reset the clock on their ‘last seen’ date (often finding them too!). In theory any species could go extinct in between its last seen date and a more modern observation and so we have to factor in the effort that’s gone into finding organisms of a species rather than declaring a species extinct after x amount of time has passed. Some of my favourite examples of species which exist in an existential limbo until ‘rediscovered’ includes a species of nautilid only (looked for and) seen twice in 30 years and beautifully illustrating that even large species can slip under the radar, 5m long whales that have only been seen a handful of times. Even some of the most well known and loved animals can surprise us with hidden diversity including giraffes which were split into four species in 2016 and even a new species of orangutan in 2017. Such findings start a new book on the recorded history of a species as well as force us to reevaluate (where possible) historic records. Large scale citizen science recording schemes can help us with a scattershot of records to help fill in some of these blanks, however, these kinds of projects can only work with species easy to identify by sight, in areas where people are likely to go and organisms which are easy to find. 

How Do We Know A Species Is Extinct?

This brings us onto a really important question. If you caught the news about the Sympterichthys unipennis, you may have had this same thought. In the most recent estimate of how many species there may be on Earth, we’ve not even escaped the error margin in terms of described species:- species which have been given a name, a detailed description, DNA sampled and deposited in a museum collection. To further horrify matters, many, many, many species are cryptic, that is, they’re extremely difficult to locate. A huge number of species, I wish I could say what proportion, like our handfish have only ever been recorded, seen or collected ONCE. If we think of one of the iconic groups of biological conservation for example, elephants we can visualise how we might investigate how they’re doing. They’re large animals, relatively easy to identify and they make a big impact on the environment. It’s not quite as straight forward as that (in fact it’s really really difficult) but we can at least imagine how we’d go about finding, counting and assessing elephant species (interestingly only 2 out of the 3 species has been assessed by the IUCN) and characterising each species’ health and assigning a conservation status. Now turn to thinking about deep sea species or tiny molluscs or organisms that live in between grains of sands. How do you even survey those, work out the extent of their distribution let alone work out whether they are in decline or under threat? It’s difficult and for some species impossible. I want to really emphasise this because I don’t think it’s widely appreciated but we know very little about most species of organisms and there aren’t anywhere near enough experts working on organisms in the field

So it’s for this reason that it’s sort of a little miracle that any species has an IUCN status at all. We have to know that a species exists in the first place (‘what is a species?’ and ‘how do you identify species?’ are blog posts for another time) then undertake painstaking fieldwork to try get a good bearing on how that species is faring as a group. This is often called ‘ground truthing’ especially in reference to terrestrial organisms and some of my colleagues at the museum undertake this painstaking work. The handfish is an excellent example of how this sometimes goes. A specimen was collected and described and determined to be a new species of handfish in 1802. That’s a single data point. “This species woz ‘ere 1802” is obviously not enough to assess where this species normally lives, its range, preferred prey, life cycle or migration patterns. In order to say anything more about this species you need to head into the field, starting with the locality information of your museums specimen (if it has anything…) and start meticulously surveying. This is, again, another hugely costly and expensive process. Biologists employ some meticulous detective work factoring in seasonal changes, geology, geography as well as more generic surveying work to generate some of this data but again, there aren’t enough of them and sadly this kind of work has a very low status when it comes to the kinds of research which are valued at universities at the moment. Cold stores across museums, universities and government agencies are filled with decades worth of material in need of expert sorting that would provide some of this baseline information from field seasons in the 80s, 90s and 2000s and probably going back further in some organisations.

Fortunately, for our handfish there have been dedicated surveys specifically looking for handfish and the handfish conservation project has a nice page showing this effort for two other handfish species over 7653 surveys have been taken (!) but you see that many areas of the coastline have not been surveyed at all, some sites have been surveyed up to 400 times and others only a handful. This simple map is the result of decades of work and I imagine it’s these and other surveys which were used as a basis to finally suggest the smooth handfish as extinct. Now it could be that there’s still a population hanging out in a hard to get to place or that surveys were the wrong time of year for this species to be about but in this instance, the experts have (understandably) inferred that the chances of this species existing are slim. Now because the smooth handfish was only ever known from this one place globally its presumed absence from this one place after concerted effort effectively means a suggested global extinction. Species are sometimes rediscovered and celebrated when they are but for the time being our best effort guess is the smooth handfish is extinct.

Plenty More Fish In The Sea?

So why is this a milestone as I mentioned earlier? Well as I’ve hopefully demonstrated it’s very hard to declare a species extinct and it’s even more difficult for marine species for a whole host of reasons; marine organisms can range for vast (VAST) territories and depths, fieldwork is difficult, expensive and dangerous, marine habitats are far harder to characterise and discern than terrestrial ones and then some. Unlike (some) terrestrial species it’s much harder to confidently ‘ground truth’ the existence or not of a species. The difficulty of describing species as extinct is the reason that you may sometimes find a cantankerous biologist who will declare that we aren’t living through a sixth mass extinction- just look at the IUCN Red List- less than 1% of assessed species are extinct, even less if we factor out the data deficient ones. However, this is (hopefully) knowingly massively understating the sheer task of discovering let alone describing let alone characterising let alone listing any species on the Red List. In the case of the smooth handfish it’s the happenstance of a restricted range and phenomenal research effort that has allowed this listing to happen there are undoubtedly many others needing this same attention. It’s not just the species on the Red List we should be worried about it’s the vast majority which aren’t. We can’t even begin to see how we’re impacting them in real terms which is where ecological modelling, to some extent, helps. It’s hard to determine when marine species go extinct, which is why you’ll only find extrapolations from terrestrial megafauna in the small print under so many headlines along the lines of “World on track to lose two-thirds of wild animals by 2020, major report warns” but this is why we should take note when it does happen.

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