River Monsters (30 page)

Another sturgeon, known as the Croesyceiliog fish, broke three nets and tipped over two coracles near Towy Castle in June 1896, but it was eventually recorded at eight feet, four inches and 320
pounds. The captor, ‘Billy Boy,’ sold the fish to ‘Slippy Dick.’ In the River Severn, sturgeon were commonly caught in salmon nets until the 1950s, including a fish
reportedly weighing over 500 pounds that was taken from Lydney to London’s Billingsgate fish market in June 1937. Further north, a sturgeon of 460 pounds was reported from the Yorkshire Esk,
and in 1956 the trawler
Ben Urie
netted a 700-pound fish, ten feet, five inches long, off the Scottish Orkney Islands. The sturgeon’s subsequent decline can probably be attributed to
intensive sea fishing, pollution, and blocked migration routes, but we can’t be certain whether the species ever successfully bred in British rivers. To be fair, these fish were more likely
to be strays. Even those renowned navigators, salmon, occasionally swim up the ‘wrong’ river; in fact, the figure is at least 10 per cent. But this actually signifies greater
perfection, from the long-term survival point of view, than a 100-per cent homing rate. Scientists believe that having a small percentage that ‘get lost’ helps the salmon to recolonise
territory lost because of a changing climate, such as an ice age advancing and receding.

The most celebrated lost sturgeon of recent years was nine-footer weighing 264 pounds that was netted in Swansea Bay, off south Wales, in 2004. A message was duly sent to the Queen, who declined
the offer of a fish supper and said that the captor, Robert Davies, could ‘dispose of it as he saw fit.’ But despite this royal go-ahead, sent by fax from Buckingham Palace,
camera-wielding scene-of-crime officers from the Devon and Cornwall constabulary interrupted the sale of the fish at Plymouth fish market. After all, Baltic sturgeon are a protected species in the
UK, which is very odd when you consider that individual sturgeon turning up in British waters are non-native vagrants, and the species has probably never bred here. Even so, Mr Davies was looking
at a maximum penalty of £5,000 or up to six months in prison. (He would have been in the clear if, instead of selling it, he’d given it away or eaten it himself.) The story then took
another twist when, right after the sale, the fish disappeared. As the net was closing in on the sturgeon’s buyer, there was a phone call, and the fish, by now called Stanley, was taken into
police custody at ‘an undisclosed location’. The situation had been resolved by offering the fish to London’s Natural History Museum, which was delighted to acquire this large,
rare fish. But here, the curator of fishes Oliver Crimmen made an observation that let everyone off the hook. He was struck by the short, blunt snout of this fish, and after further tests, he
identified it as an Atlantic sturgeon from – final double-take – North America (
Acipenser oxyrinchus oxyrinchus
). (Interestingly, this catch supports the theory that
Baltic/British sturgeon are a recent offshoot, dating back just 1,200 years, from North American sturgeon rather than a subpopulation of European sturgeon, which have been isolated from their
western Atlantic cousins for some sixty million years.)

There’s one other thing that sturgeon share with salmon. Both have populations that buck the general trend and don’t migrate to the sea. Even with the loss of rich marine feeding
grounds, they still manage to grow to maturity and successfully breed. In northeastern North America, from Maine to Ontario and Newfoundland, several lakes contain a landlocked subspecies of the
Atlantic salmon. In Europe there’s the entirely freshwater huchen (
Hucho hucho
), alias Danubian salmon, which has been caught to 127 pounds, and in Asia there’s the nonseagoing
taimen (
Hucho taimen
), which has been recorded up to 231 pounds. In North America the once abundant but now rare lake sturgeon (
Acipenser fulvescens
) of the Great Lakes, Hudson Bay,
and Mississippi ecosystems survives without a marine phase in its life cycle; and there are some eighteen landlocked populations of white sturgeon, mostly because of dams. But there’s one
population of white sturgeon that was naturally cut off from the sea. The Kootenai sturgeon, named after the river where they live, were cut off from the sea when glacial deposits from a retreating
ice sheet created impassable waterfalls in the river’s course. Despite this, they managed to breed and sustain their numbers for ten thousand years, evolving into a distinct genetic strain of
white sturgeon – less solid in body, as might be expected, but otherwise thriving. (Only now, after the construction of the Libby dam in Montana, have these sturgeon stopped breeding due to
reduced water flow, which is causing siltation of the clean gravel beds that sturgeon need for spawning.)

Could something similar have happened in Iliamna? At its western end, the lake is confined not by mountains but instead a flat glacial moraine, over which the Kvichak now meanders to the sea,
fifty miles away and just forty-six feet below the level of the lake. Before this outwash deposit formed, what is now the lake was probably once open to the sea. And if so, it’s perfectly
possible that a population of sturgeon became isolated there. (Although the Kvichak is technically navigable, its shallowness and clarity would rule against sturgeon using it as a regular highway.)
Once such a hypothetical population is there, all it needs to survive is an adequate food source and a place to breed. The prodigious runs of salmon fulfil the first requirement. In fact, why waste
energy getting food from the sea if that seafood comes to you? For spawning grounds, the areas where feeder streams run into the lake ought to provide a perfect combination of deep-enough, safe
water as well as clean, well-oxygenated gravel.

Although this scenario is only a ‘thought experiment’, in my mind it makes a pretty convincing case for declaring this a mystery no longer. What’s more, this conclusion also
appears to settle another mystery: the likely identity of the world’s biggest freshwater (nonmigratory) fish. All we need now is for somebody to catch one . . .

There’s one more thing that makes me think the Iliamna monster is a sturgeon. While filming near the village of Nondalton on the river between Lake Clark and Lake Iliamna, we met up with
three lads fishing in a boat who had seen the first series of
River Monsters
and were curious to know what we were doing here. I said we were investigating the monster, and asked if they had
any ideas about what it was.

‘Yeah, it’s a sturgeon,’ one of them said.

Now I find myself idly wondering about those twenty-foot-long objects that sonar detected in Loch Ness, moving between mid-water and the bottom. There’s also a story from the 1930s of a
woman who saw a large creature swimming up the five-mile-long River Ness towards the loch. She described it as looking like a crocodile with tusks. Now, if you had never seen a sturgeon before,
think how you might describe a large animal with a pointed snout, bony plates on its back and long, dangling barbels. Somebody should go there in the summer months and cast a dead salmon on very
strong line where one of the feeder rivers comes in, either off Invermoriston or in the mouth of the River Enrick near Castle Urquhart. The latter location is opposite General Wade’s Military
Road, but I’m not taking that as any kind of omen. After taking six years to catch a goliath tigerfish and another six for the arapaima, I think I’ll leave this one for somebody
else.

14

ALIEN INVADERS

Snakeheads made US national headlines in 2002 when northern snakeheads (
Channa argus
) were caught from a pond at Crofton, Maryland, just twenty miles northeast of Washington, DC. Some of
the fish were two feet long, already half their maximum size, with razor-sharp cutting teeth and markings reminiscent of a reticulated python. But the two-inchers were more scary. This meant that
this fish, normally a native of China and one of the largest of the thirty-odd snakehead species, had successfully bred. Right next to the pond was the Little Patuxent River. If there was a flood,
the fish could spread to there, and then they would really be on the loose. Maybe they could even get there without a flood, thanks to their suprabranchial organ, a breathing chamber above the
gills, and their alleged ability to colonise new waters by wriggling over land. They had to be stopped.

Mindful that this species, which survives harsh Asiatic winters, could potentially colonise much of the United States, wildlife officials took the drastic step of poisoning the pond with
rotenone. They killed six adults and more than a thousand juveniles. The emergency was over.

The mystery of how they got there was cleared up a little while later. A man originally from Hong Kong had bought a pair of the fish from an Asian market in New York in order to make a medicinal
soup for his sister, who was ill. But by the time the fish arrived, she had recovered, so he kept them in an aquarium. It wasn’t long, however, before they were eating twelve goldfish a day,
so he decided to evict them.

But in south Florida the discovery of snakeheads came too late. In 2000 fisherman Bob Newland caught a fish that he didn’t recognise and took it to the state’s exotic fish lab. Here,
fish specialist Paul Shafland didn’t recognise it either. Only after ploughing through a tome of world fishes did he have a positive ID: bullseye snakehead (
C. marulius
).

‘After that he wanted to know exactly where I caught it,’ Bob told me, as we bank-fished a canal near a busy highway. ‘I said I caught it on a golf course in Tamarac. And he
said, “No, I need to know what hole you found it on”.’

Shafland hoped the fish would be confined to just that one pond so he could quickly eradicate them. But when his team sampled the surrounding canals using electro-fishing boats to stun the fish
to the surface, they found them there as well. ‘South Florida is a maze of interconnected canals,’ he told me. ‘We couldn’t have created a more ideal habitat for
snakeheads.’

I saw that for myself when I went fishing with Alan Zaremba, a guide who normally takes clients fishing for peacock bass. These fish are also not native to Florida but instead come from the
Amazon. Unlike snakeheads, however, they were introduced officially and are hence classed as ‘exotic’ rather than ‘invasive’. This partly comes down to fish snobbery: the
fact that they’re considered desirable ‘game’ fish – like trout, which continue to be spread around the world despite biologists’ concerns about their impact on native
species. But more to the point, peacock bass are not able to breed in cold water, so there’s no risk they’ll spread. And there are no stories that peacock bass will kill you.

Alan’s top snakehead bait is a rubber frog. This is used in conjunction with a special kind of single hook, which has the point precisely aligning with the shank and the bend shaped rather
like a keel. This is threaded into the bait so the point nestles invisibly in a groove in the frog’s body. Thus mounted, it can be cast among weeds and branches without fouling, but the
action of a snakehead chomping down on the soft bait exposes the point. With my briefing over, Alan quietly manoeuvred me into position using the electric trolling motor. I cast beyond some lilies
and then, with the rod held high to keep the frog on the surface, brought the bait chugging back towards me. On about the third retrieve, passing a gap in the pads, the surface opened and the rod
yanked around. I wasn’t expecting this at all, but somehow I managed to do everything right – hustling the fish out of the weeds and into the open water and then alongside the boat. In
the clear water I could see what it was, so I gripped its lower jaw with a metal grip, rather than my fingers, and swung aboard my first snakehead.