Amazing Anguillas

Molly McGinnis

September, 2005 issue of Signals from TARSUS

Author's note: When I first started thinking about natural history in Ransome's life and books, I gave the working title, "Totem Animals" to my thoughts about title animals and animals that drive the stories. In this issue we have a real totem, the carved eel in Secret Water. The living fish appears only momentarily there, but eels are an important part of the plot of The Big Six.

"You see the eel is the totem of the Children of the Eel. That's the name of the tribe. But it's an awful secret." Secret Water

Anguilla Anguilla (Europe)
Anguilla rostra (America)

European and American eels look just alike, and the handsome silver eel of the Secret Water totem could be either species. Don carved and painted his eel well: you can see the pectoral fin standing stiffly out near the face, and the long wraparound fin that runs down the back, around the tail and halfway up the ventral side. The unhappy eel is flattening the fin down onto her back (an eel this big is sure to be a female), and who can blame her? It shows as a lighter, segmented line in the picture. The Anguillas are the freshwater eels, and until the early 20th century their lives were as big a secret to biologists as those of the Children of the Eel were to the Missionaries.

Suffering Lampreys!
To many Americans, especially those of us who live in the west where there are no freshwater eels, an "eel" is a Lamprey. But Lampreys are Agnathans (Greek, no jaw), the lowest fish on the evolutionary scale, and eels are Osteichthyes (Greek, bone + fish), the most advanced. Lampreys don't have skeletons – just a rod of cartilage to support the body, and, as you might guess from the name, they don't have jaws. If you were to catch a lamprey, you would know it by the row of seven round stomata, openings over the gills, on the side. Adults are parasitic on other fish, and if you turned your lamprey over you would see a round mouth that attaches the lamprey to its victim, and rasp-like teeth that grate away the host's flesh. When the canals connecting the Great Lakes to the Atlantic ocean were built, Sea Lampreys infested the lakes and nearly destroyed their commercial fisheries, until larvicides (poisons specific to lamprey larvae), were developed. Lampreys were an important food for some American Indian tribes, and are considered a delicacy in Europe: the few caught commercially are exported.

Great Congers!
Congers and morays are in the family Anguillidae, like our Totem eel, but they are sea eels, living all their lives in salt water. Conger eels were fished commercially and prized for their rich gelatinous meat until well into the twentieth century.

Wriggling Elvers!
Harry the eeler says eels are born in the mud and live in the mud, and scoffs when Tom Dudgeon tries to tell what he's learned in school: that the eels in Harry's live box were born far away in the Sargasso sea and that those which escape nets and spears will return there to spawn.

Tom is right, but this was new knowledge when The Big Six was written. It had been less than thirty years since the eel life history began to be worked out. In 1908, Italian biologists proved that a quite un-eel-like fishlet called Leptocephalus brevirostrus ("thinhead shortsnout") was the larva, the first stage after hatching, of the eel. Leptocephali collected off the coast of Sicily were the key that finally unlocked the mystery of the eel, for its hatching grounds were found not by tracking adult eels out to sea but by following the paths of the larvae backward. In 1911, only three years after L. brevirostris was identified as a larval eel, one was netted off the Faeroes, and Johannes Schmidt, a biologist on the expedition that netted it, saw how important it was that a leptocephalus had been found hundreds of miles from the shores of Europe. For the next several years Schmidt followed the larvae backward along their paths, always looking for the next smaller form. The hunt was disrupted by World War I and by shipwreck and fire, but finally, in 1926 – around the time when Tom Dudgeon was born – Schmidt netted the smallest larvae of all, three millimeters (about two tenths of an inch) long, no bigger than fingernail parings, scarcely larger than eel eggs.

Schmidt caught these tiniest of leptocephali in the curious sea within a sea called the Sargasso, a two million acre lens of water off the coast of Bermuda, contained and raised by slowly moving currents rather than by solid land. The slowly swirling boundary currents raise the Sargasso as much as nine meters above the surrounding waters, and within the lens the water is several degrees warmer and several parts per thousand saltier than the water of the Atlantic Ocean just outside and below it. The Sargasso is a clear, oligotrophic sea (Greek: oligo<, few, troph-, nutrients), with hardly any large aquatic life-forms to eat the eels' eggs or the tiny, passively floating leptocephali, though there is plenty of microscopic life for them to feed on.

The hatchlings are leaf shaped, flat and transparent, with a few sharp teeth and a big dark eye, and in two years, by the time they reach European shores, they will have grown to about 7.5 centimeters long (almost three inches). Now they begin a metamorphosis as dramatic, in its way, as that of caterpillar to butterfly. They shorten. They lose up to 90% of their weight. Their sharp teeth disappear. From a flat fish-shaped creature they become something like a swimming string. They are still transparent, so transparent that you can see their hearts beating, and are now called glass eels. As the glass eels come to fresher water near the river mouths they darken to become more recognisably eel-like elvers.

The elvers transform again, into yellow eels with bronze or yellow-brown backs and creamy buff bellies – a countershading that helps make them invisible in murky summer water or in mud. The females move up the estuaries to rivers, streams, lakes, and ponds, while most males hang about the river mouths, carried in and out by the tides. Inland, eels slither across pastures and roads to get to water and even climb streamside trees, dropping into the water from the branches.

Eels are opportunistic feeders, like most very successful species, and will eat any kind of animal they can catch, as long as it's fresh. Eels are not generally fast enough to catch game fish and biologists don't see eels as any kind of threat to salmon or trout fisheries, though gamekeepers may. Even large eels feed mostly on invertebrates, with whatever small fish they can catch. One fish that eels can catch is other eels, and yellow eels have been caught with 50 and more elvers in their stomachs, harvested from the great masses of elvers moving upstream.

There will be one last inward and outward metamorphosis in fresh water. After the yellow eels feed and grow for 10 to 20 years or more, ribbonlike ruffly gonads (egg or sperm-producing organs) begin to develop, the body fluids become less salty, and the digestive system atrophies: the eels will never eat again. They change color one last time, to the handsome silver and black of Ransome's drawings, and the body becomes firmer as the muscles are packed with fat. They are now silver eels, and migrate toward the sea, to disappear into its waters forever. Over all the recorded centuries, only a dozen or so eels have been caught at sea, and even today none have been tracked to the Sargasso. In 1898, an adult eel was collected from the stomach of a sperm whale, which tells us no more than that the eel was well out in the Mid-Atlantic and many meters below the surface, because that is where sperm whales feed. That specimen remains the only eel to be collected from the open sea. A handful of adults have been caught off the shores of Britain, metamorphosed yet again, and in ways that suggest they are deep-sea swimmers. The eye has become very large, the fan-shaped pectoral fins are now pointed like those of other fast-swimming ocean fish, and the color is a uniform bronze.

Bobbling Babbers! "The old man talked of eels... 'We'll have a look at them old eels,' he said... The boat stopped, and the old man reached down with a pole that had a hook on the end of it." The Big Six

Surely no fish have ever been harvested in so many places, in so many ways and at so many sizes as eels. Eels were caught in estuaries and rivers, in streams and lakes and farm ponds, in brackish water and fresh. Though eels aren't mentioned in the books set in the Lake Country, there were enough eels there to support a small commercial fishery. Elsewhere, mudbanks where yellow eels lounged through hot summer days or lay buried in winter torpor were so thick with eels that they were harvested just by spearing at random into the mud. They were trapped in baited cages of withy or netting, or gathered by weirs (fish fences across a stream) and hand-netted. Silvers migrating downstream were caught in setts like Old Harry's: drift nets set in a "V" to guide the eels into tubular, hooped fyke nets. Many-hooked lines like Don's night lines (trot-lines, to Americans) caught eels by dozens, and "babs" of fine yarn wound into a ball, with no hooks at all, caught them by the teeth. Commercial fishermen found eels in their nets and on their long-lines and swore, and cut them loose, hooks and all; sport fishermen caught eels by accident and swore, and cut them loose; and fishermen looking for dinner caught them and delighted, for eel is one of the richest and tastiest of all fish.

Farewell and Adieu, Anguilla Anguilla
In time of the Swallows and Amazons there were still so many eels that no amount of harvesting made a dent in their numbers. Seemingly unending streams of eels returned from the ocean to be caught: tiny glass eels migrating upstream in spring, yellow eels going nowhere in particular at any time, and finally, mature silver eels on their way to the sea in the fall. There should have been enough eels for everyone, for forever.

Then the world changed. Dams were built, more than 15,000 of them across the rivers of the Eastern United States where young eels once swam upstream to feeding grounds and mature eels migrated downstream to the sea. The turbines of 1100 hydroelectric dams chop up eels just as efficiently as they chop up migrating salmon. By law, any of several agencies have the power to require bypasses around dams so that eels and other fish can get by, but hardly any bypasses have been built. Very few young eels swim and slither upstream past the dams, and very few adults slither or swim down.

Commander Walker marooned the S&A's on Secret Water because he was called away to deal with the beginnings of the Second World War. Paradoxically, the war brought a new prosperity to a rebuilt Japan and eventually to China, countries where eels are a special delicacy. More people could buy eels than there were eels to buy. Japan and China have their own freshwater species, and the Japanese learned to farm them, but there still weren't enough eels. Because eel eggs won't hatch in artificial environments, the only way to farm eels is to catch elvers and glass eels and feed them to size, and there weren't enough in Asia. Japanese eel farms began buying elvers from Europe, and started a feeding frenzy among fishermen. Prices for glass eels and elvers skyrocketed. Modern nets could catch almost every tiny glass eel and elver, and did, leaving hardly any to mature upstream. When live elvers and eels began to be shipped around the world, eel parasites and diseases travelled with them and are now affecting both Western and Far Eastern populations. Eel numbers were dwindling before the elver boom, but with almost no elvers escaping dams, nets, and disease to mature, there are almost no young eels to replace the adults when they finally migrate to sea. European eel fisheries have collapsed and Anguilla anguilla is on the verge of extinction. ICES, the International Council for the Exploration of the Sea, has now (June 2005) recommended that all eel fishing in Europe be halted. Some biologists fear that European Eel populations have already declined beyond recovery, but if not, the moratorium could save the species.

Meanwhile, the United States and Canada continue to dam rivers and to harvest eels and elvers for eel farms, for bait, and for European tables, so that fewer and fewer American Eels reach the Sargasso to spawn. It has taken many years to fish out existing adult populations, because eels are so long-lived and so slow to mature, but it's now clear that almost all of the silver eels migrating downstream are the last remnants of aging populations, with hardly any young eels getting past the dams to replace them. If blocking of streams and unregulated harvesting aren't corrected, and soon, our eel too could become extinct. Action has been slow in coming, but finally, in late 2005, the United States Fish and Wildlife Service is preparing to petition the Environmental Protection Agency to list the American eel as a threatened species, and Canada is also taking steps to protect eels. If Anguilla rostrata is granted threatened status and if we can act quickly enough, if we can put dam bypasses in place so that eels can get to their upstream feeding grounds and migrate back down, if we can curtail harvests so that enough adult eels to maintain the species reach the Sargasso Sea and spawn, our eel populations may recover and we may not have to say that final farewell after all.


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