Guest Blogger time for Richard Freeman again. It almost seems silly introducing Richard to you all once again when he makes an appearance as guest blogger several times a week. However, our viewing audience/ readers (whatever you like to call yourselves) is growing so fast that it is certain that some of you missed the last time I introduced him.
The recent story of a zander attacking people in a Swiss lake (see above) seems a bit of a letdown when you hear this freshwater Jaws was only a little over 2 feet long.
Monster fish in freshwater do exist however. Back in the late 1990s Jon started the Big Fish Project to collect and investigate stories of outsize fish in freshwater. I admit that I was very sceptical about the whole idea at first. I thought all it would elicit would be twice-told anglers' tales and the odd trout a few pounds larger than average. The one exception in my mind was the eel that I thought (and still think) can reach fantastic sizes under certain circumstances and is probably responsible for a number of lake monster stories.
However the Big Fish Project led to the CFZ’s most successful expedition to date; not to some remote jungle or dessert but to a small lake in Lancashire. The CFZ were called in to investigate claims of a monster the size of a car lurking in Martin Mere, a wildfowl reserve. The creature was reported to be attacking full-grown swans.
At first I found the whole idea unlikely. This view was reinforced when I saw the lake. It was no more than 2 acres in size and only 5 feet deep at its maximum. I said to Jon that it was highly unlikely that a large predator could live in here. Half an hour later I saw the monster of Martin Mere. It surfaced only six feet from where I was standing on the bank. It was around 8 feet long and thicker around than me. It was an oily blackish-green with a texture like wet rubber and a shape like a huge sausage. The creature bore no scales but had a small fin on its back.
I instantly knew what the monster of Martin Mere was: a wells catfish Silurus glanis. Imported from Russia by the Acclimatisation Society in Victorian days, this is the biggest catfish in the world, reaching 16 feet long in its native range.
I saw the beast twice and we later tracked it on sonar. Since then we have visited Loch Ness and Loch Morar in search of giant eels. Recently we have acquired 6 European eels to study their growth.
Mutant eels aside, the question of what is the largest freshwater fish is a difficult one. The current leaders are the Chinese paddlefish Psephurus gladius with a length of 23 feet and a weight of 1,100 pounds. This giant may be on its way to extinction as none have been seen since 2003 and no baby fish have been seen since 1996.
Gehzouba hydroelectric dam divided the Yangtze River into two sections, cutting off the migratory route of the paddlefish in 1983. It separated the spawning grounds from the feeding grounds and has probably sentenced this fish to extinction.
Another contender is the Mekong giant stingray Himantura chaophraya with a total length of 23 feet (including the long tail) and a weight of 1,100-1,300 lbs. Deforestation and dam construction has caused this species to become critically endangered in Thailand.