Stories of of big fish
by Markus Bühler
Humans have been always fascinated by large animals, the larger, the better. Hunters tries to shot the biggest bears or elephants and anglers tries to catch the largest fish. Unusually big animals make good stories to tell, and it´s no secret that especially anglers have often a strong tendency to exaggerate the sizes of their catches. In fact, it nearly seems there are next to no photos of fish caught by anglers around, which do not involve forced perspective. That´s even weirder, as anglers even use massive forced perspective at record-sized fishes which really wouldn´t need such a thing to look impressive. So it is not surprising at all, that there are a lot of totally exaggerated sizes for many animals around, especially for fish, but for certain reptiles as well. One reason for this is probably the common idea, that fish and reptiles can grow for their whole lives, and if they live long enough, they could theoretically reach every size. However, reality is different. A lot of fish and reptiles and amphibians as well have determinated growth, i.e. they reach a certain size within a certain time, and show nearly no more additional growth for the rest of their lives. Some species really grow for a long time, even for decades, but usually their growth slows rapidly over the years. Most of the growth is attained during the early years, and especially the time before the reach of sexual maturity is important. Even animals typically regarded as long-time-growers like crocodylians, reach most of their size within the first two decades of their lives, even extremely large specimens.
In general the size an animal can reach during its life, is mainly dependent on its genetic conditions, the availability of food and some other factors like temperature or for example water quality to some degree for some fishes. Age is often not even that important as many people think. Of course record-sized fish are usually no more youngsters, but they also don´t have to be methusalems. For this reason estimating ages based on size alone doesn´t work, because some specimens will reach sizes much bigger than average at a quite early age whereas other ones live extremely long, but stay small for their whole lives. All species have a certain size range, and even the very largest individuals are usually within a certain restricted range over the averge.
As obsessed humans are with giant animals, as bad they are often at actually estimating sizes. I know it from personal experience, how people overestimated the length of an animal they even saw from close direction for 200%. Things get often even worse, if the animal in question is only partially visible, or even underwater. A lot of people get also fooled by photos, for example when they see but don´t realize forced perspective. Sometimes it doesn´t even need forced perspective, but only an exaggerated size data for a photo, and a lot of people will still not realize a difference to the real size.
This leads to some problems. People are often bad in estimating sizes, people often like to exaggerate things and people like unusually big animals. This leads to the already mentioned exaggerated size data reported for many animals. The really big problem is that such exaggerated sizes found alarmingly often their way even into scientific literature. A lot of sizes you can find for certain animals in many books, are actually nothing but anecdotal stories, which don´t date back to confirmed data or measured specimens. Especially in the larger species, there are countless of such cases. You can find alleged lengths of 11, 18 or even more than 20 m for oarfish, but this was nothing but hearsay, no specimen was ever measured to have this length, in fact the very largest specimens which were measure, were only around 6 m. A typical trait of exaggerated size, especially in big-fish-stories, are non-correlating length and weight data. Weight grows with the cube, and a lot of people don´t realize that doubling the length means increasing the weight for eight times. So the weights for exaggerated animals are quite often much too light. It´s really surprising that even a lot of ichthyologist never realized how absurd many figures for alleged record animals are, like this bizarre figure of 4,5 m and 200 kg for the arapaima. With this proportions, it would look like an eel. Instead, one author copied from another, without any critical thinking or some minutes of simple weight calculation. It´s also really strange why so many authors apparantly didn´t wonder why the alleged record-specimens are often so much bigger than any confirmed sizes from more recent times. A reason for this is probably the wrong believe that overfishing reduced maxium sizes, and in earlier times, there were bigger record specimens. This could be the case to a certain degree for some species, however not to such a degree, it would explain this differences. In fact, the largest confirmed record specimens from historic times usually don´t differ that much in size from modern record specimens. Every report of an animal much bigger than anything confirmed should raise sceptisism. However, that´s often not the case, because people want this animals to exist. Probably as a result of decades of radiation-or toxin-caused monsters in TV, books and comics, a lot of people are also still in favour of „freak specimens“ much bigger than everything known. Again, such a thing doesn´t exist. Even massive doses of growth hormones for example can enhance the growth only to a certain degree. I´ve been interested in the growth of animals and maximum sizes for certain species since many years, and I couldn´t find a single case of such a „freak specimen“ ever. As a rule of thumb however, I found out that the largest confirmed specimens of a species are usually around a third longer than the length which is usually regarded as „big“ but not too unusual. Of course this isn´t a scientific method, but it works very well, and it can be a great help to determine if a reported size is realistic or not. It can be a bit problematical to determine what exactly „big“ is. In general I would say, it´s around 10-15% longer than average. Especially in some fish, there isn´t a real average size, as populations usually consits of a large number of small juveniles and subadults, so you have to take a look at adults only. I´ll make some examples for this method. The first one is the animal on which I made most research for growth and maximum sizes for around a decade, especially as there is so incredibly much wrong data around. It´s the European wels catfish Silurus glanis. In Central Europe, this species grows comparably often to a length of roughly 1,6-1,7 m as an adult. Lengths of 1,9-2 m are comparably rare, but not really that exceptional. So let´s define „big“ as around 1,9 m. At 33% longer, it would be 2,52 m. By chance, this is only 5 cm over the length of a really exceptionally huge specimen which was for years the largest on record in Germany. In other parts of their range, average sizes are bigger and maximum sizes as well. Especially in parts of Southern Europe, where wels catfish were introduced, they grow extremely well, not only due to a large amount of prey fish in big rivers, deltas or reservoirs, but also because they grow faster and during a longer time of the year in warm water. Lengths of 2,1 m or more are much lesser rare in water like the Italian Po-delta or the River Ebro at Spain, but still, they are far over average. So if we define 2,1 m as big, we have get a length of 2,79 m for the probable maximum length. The largest wels from Italy, and actually one of the very largest ones ever confirmed, was 2,78 m in length. As I wrote, this is a rule of a thumb, if you define the length for „big“ or „average“ for some centimetre more or less, you´ll get slightly higher or lower figures. But still, it gives you an idea what can be probable and what not.
Another typical typical trait of confirmed records is they follow a Gaussian distribution, i.e. there are the lesser specimens in a certain size range, the close this size range is to the biological maximum size. So for every record-holder, you find some other specimens which were somewhat smaller, the more the smaller they were. If a reported animal is said to be much bigger than a large number of confirmed record specimens, it´s next to sure not true.
So, why did I write this? Because this is important for cryptozoology. There are a lot of animals in cryptozoology, which are supposed to be outsized specimens of known species for example. Furthermore, there are also some cases in which certain „monsters“ are supposed to be outsized specimens of species known to science. But to work on a respectable base, and to come really close to the real explantions of cryptids, you have to use the right data. For example, if you read that wels catfish grow up to 5 m, this can sound like a great explanation for lake monsters in Great Britain, where wels were introduced in some areas during the last 150 years. But besides the fact that wels catfish grow for climatic reasons even much slower in Great Britain than in Central Europe, they don´t even come close to the alleged 5 m at all. In fact, there is not even one single confirmed specimen which just reached 3 m. It´s the same thing with sturgeons. There is no doubt that certain sturgeon species grow extremely big, but there is a lot of obscure data about their real maximum sizes. Even today, you can quite often read that beluga sturgeons (Huso huso) grow to 7, 8, 9 or even 10 m. You can still find this in otherwise good ichthyological books, but only because some old unconfirmed data from the time prior to 1900 was copied again and again without critical thinking or research. As usual, the weights for the very largest reported beluga sturgeons are much too low, as in most bigh fish stories. So, how big can beluga sturgeons really grow? I have to admit, it is really not easy to say. But considering all confirmed data, various weight calculations based on specimens with known length and weight, and taking photographic evidence into account, it´s probably around 5,5 m or perhaps somewhat more. In any case, it´s well below the often quoted maximum lengths of 8-10 m. You have to imagine how big this difference really is, it´s 45% longer, or to use weigh, three times as heavy. Beluga sturgeons are quite massive fish, and already a specimes of 4 m can weigh around a half ton. It seems strange that nobody ever calculated how much a hypothetical beluga at 8-10 m – the size of a large minke whale – would really weigh. At 9 m, it would weigh around 5 tons, and at 10 m even close to 7 tons, much more than every beluga sturgeon ever reported.
I´ve been searching for photos of large sturgeons since years, but I could never find a photo of a specimen close to the largest reported maximum sizes of 7-10 m. That is interesting, because even around 1900, when photography was still comparably unusual, people found very large fish already unusual enough, to take photos of them. At this time, there was not that much environmental destruction and pollution, and fish stocks were much lesser overfished than today. But yet, even the very largest beluga sturgeons on historic photos were not considerably bigger than the largest recorded specimens from the last decades.
So, what can we conclude from all this? A lot of size data is just wrong, even in scientific literature, and you should always be really sceptical about reports of outsized animals, and invest really critical research when you want to know the real maximum sizes. This can be sometimes quite hard and time-consuming. I like unusually big animals too, but I want to know how large the really are, and not how large I want them to be.
I am also not that sure about the alleged teeth in kalugas, as I couldn´t find any reference for them, except for the wikipedia-article, nor could I see any teeth in the mouths of any kalugas at photos. I suppose this information comes from "River Monsters".
Since last year, I have also a small sturgeon in one of my ponds, a sterlet x russian sturgeon hybrid. It´s really highly interesting to watch it, and it´s really interesting what strange behavior it sometimes show. Sometimes it swims so close to the surface, that its caudal fin and parts of the back are above the surface. Even stranger, it sometimes holds its head above the surface. To my great surprise, it even started a short time ago to feed on pellets at the brink of the pond, often with its head fully out of the water. It even feeds on pellets above the water level and out of my hand.
I´ve been collecting photos of giant sturgeons since years. But none was ever close to the largest reported sizes. However what I found was, that even around 1900 and earlier, when photos were still comparably unusual, people found giant sturgeons unusual enough, to take photographs of them. Furthermore, even today some extremely large specimens get caught on rare occasion, and I found it interesting, that the largest modern specimens are not really that different in size from the largest ones around 1900.
I attached a photo of the probably largest beluga for which I could find photographic evidence. I am not totally sure how big it really was, and there could be a little bit of forced perspective involved. I once found an old Russian photo of another one of similar size, but I couldn´t save it. But anyway, even this very largest specimens are still only around the half length of those at your scale illustration, so reports were quite obviously highly exaggerated. Perhaps you should add something which makes it sure this is not the largest confirmed length, because a lot of people take such figures serious.