Natural History

One of the most interesting theories postulated by The Centre for Fortean Zoology is the hypothesis that many lake monster sightings are overgrown eels. Now, this theory was lampooned on Penn & Teller’s Bullshit, and in the youtube upload of the Centre’s documentary Eel or No Eel, the comments are mostly negative. How could there be a giant eel any European lake?

The theory goes that some eels are sterile (“eunuch eels), and unlike other eels, they don’t leave lakes and rivers to spawn in the Sargasso Sea. They simply stay in fresh water, eat, and get big.

We do have some evidence of what happens to European eels that don’t go through their normal life cycle.

In 1859, an eel was confined to a well in Sweden. It remained trapped in the well until it was recaptured in 2008. It was over 149 years old, and yet, it had survived in fresh water all this time. It was 53.5 centimeters  (21.1 inches) long, and its eyes were unusually large.

Now, a 21 inch eel is hardly a giant animal. However, it is possible that an eel living in a more nutrient-filled environment than a well, could grow large during such a prolonged life.

However, I don’t think that the supposed large eels are eels that simply remained trapped in freshwater due to confinement or sterility. I think there is something else at work here.

One aspect of natural selection that is often left out is the human element. Now, we often hear about the peppered mouths of Britain, which come in two basic color morphs. One is lighter and perfectly camouflaged against a tree with lichens and moss on it, while the other is darker and better camouflaged against soot covered tree. With the Industrial Revolution, the darker moths proved to be better camouflaged against bird predation, and thus, the majority of the population became dark-colored. (This trend has since reversed as Britain has tried to clean up emissions from power plant and factories.)

Now, that is a textbook example of how human effect natural selection. I have also postulated that the ancient wolf population from when modern wolves and domestic dogs descend was originally much more dog-like. The wolves were curious about people and were easily tamed. When we began to domesticate other livestock, dogs and wolves began to fully split, as man selected dogs that were unlikey to prey on livestock and man began killing wolves on a large scale. This selection pressure on wolves ratcheted up as the Industrial Revolution made poisons, traps, and fire arms more readily accessible. We have selected dogs to be extremely tame and docile. They don’t fear new things as much as wolves do, and dogs have also evolved innate human reading abilities and associative learning abilities that make them rather interesting animals. Our pesecution of wolves has selected for more reactive, nervous, and fearful animals– animals that are nearly impossible to tame, even if bottle-reared. That’s why I think there is such a heightened difference between the two animals, even though every genetic study suggests that they are very closely related and are probably the same species.

Now, what does all of this have to do with eels?

Well, I think we have to consider eels as fish. More specifically, I think we have to consider eels a commercial fish. Indeed, commericial fishing is really taking its toll on the European eel. Today, it is considered a critically endangered species, and it is on the ICUN Red List. Typically, the reasons for its decline are thought to be the building of dams on rivers, which preven the eels from returning to freshwater to spawn. PCB pollution has recently been blamed for crash in European eel populations.

The European eel is in such a bad state that Norway recently banned fishing for European eels in its waters.

However, there is another factor that has also harmed eel populations. They have been overfished. Eels have been a common “peasant food” throughout European history. In fact, it is only been recently that they have been elevated to fine French dining.

And what happens to all fish species when they are overfished? In virtually every case, the size has been greatly reduced. People take the big ones. One big fish is less labor intensive to land than a bunch of little ones. And let’s not forget that some people trophy fish out the large ones.

And very often, the reduced size in fish species is reported on the news, like this story on whale sharks, this story on Alaskan and Russian salmon (which have a the opposite life cycle of eels– returning from the sea to their natal streams to spawn), and this one which blames commercial fishing for reduced fish size.

The unofficial and unverified maximum length for a European eel is 79 inches (200.7 cm). Now, that’s not a 2o or 30 foot eel, which I don’t think is likely with this particular species. However, if true, that eel was over 6.5 feet long.

Perhaps before European eels were widely exploited as a food source, eels of this size or possibly larger existed in European waters. It is also possible that there could be a throwback or two that still remains in the European eel population. It is also possible that these large eels were more common in more recent decades in remote lakes and rivers. When holiday makers visited these lakes and rivers and encountered these relict populations of eels, they thought they were monsters.

Now, I don’t have hard evidence that eels were much larger in the past. Because they were thought of as a peasant food ( and I’m not blaming peasants for eating them–just for the record), it is unlikely than any good records of them were ever kept in those early years. We’ve only started to pay attention to them when we’ve come to realize that the European eel is now critically endangered. What records we do have come from the past couple of hundred years– centuries after they became common table fare. We may simply be basing our maximum size for the European eel on what is really a species on the brink.

The truth is that in the very near future there might not be any European eels of any size left. But I think it is a logical fallacy to assume that we can determine the maximum size of European eels from the current over-exploited population. Maybe in some remote lake or river, there are a few rather large eels remaining.

The giant eel theory is well worth exploring, but I think the evidence for it may disappear before any can be found, if that evidence hasn’t already disappeared through the centuries of overfishing.