Book summary “The Book of Eels”: summary

Introduction

You live in a world where science has mapped most species, yet one creature continues to defy understanding. For millennia, the European eel has hidden its basic origins and reproductive cycle from human observation, existing as a biological enigma. Patrik Svensson explores this profound mystery by blending natural history with memoir, examining how the eel challenges human desire for complete knowledge.

The European eel is an elusive, transmuting creature that has baffled scientists for millennia and mirrors the deepest mysteries of human existence, faith, and environmental collapse.

The book navigates this complex relationship through five distinct inquiries. You will trace the biological journey of the eel, examine centuries of fishing traditions, and follow the frustrating scientific quests to uncover its birthplace. The narrative then explores captivity, longevity, and faith before confronting the current extinction crisis alongside personal memory.

• How does an animal transform completely while migrating across continents?
• Why did ancient scholars spend centuries arguing about whether eels have sexes?
• What draws you to an animal that refuses to surrender its secrets?
• How does the disappearance of the eel reflect your own changing relationship with nature?

1. The Biological Mystery and Life Cycle

The European eel undergoes drastic morphological transformations and originates in the dark depths of the distant Sargasso Sea.

From Larvae to Silver Eels

Anguilla anguilla is a creature of shifting forms. You encounter an animal that changes entirely throughout its lifespan, adapting to vastly different environments.

The journey starts as transparent leptocephalus larvae born in the open ocean. These willow-leaf creatures drift across the Atlantic via the Gulf Stream for up to three years before reaching European coasts.

You can trace distinct stages of growth:

• glass eels measuring two to three inches upon arrival at the shore;
• muscular yellow eels inhabiting fresh water for fifteen to thirty years;
• silver eels preparing for the long return journey to spawn.

The Sargasso Sea Birthplace

The origin of these fish remained a puzzle for millennia. You find that the European eel originates from the Sargasso Sea, where mature eels breed and lay eggs before dying.

This unique body of water covers two million square miles. It is located northeast of Cuba and the Bahamas, bounded by four mighty ocean currents without land borders, forming a warm, deep eddy covered in Sargassum algae where leptocephalus larvae are born in the dark depths reaching 23,000 feet in places.

Salmon and eels represent opposite approaches to life and migration. Salmon are anadromous, breeding in freshwater, living in the sea, and returning to their exact birthplace, creating distinct local populations. Eels are catadromous, living in freshwater and breeding indiscriminately together in the Sargasso Sea, with glass eels choosing European waterways at random, resulting in negligible genetic variation across the continent.

While a salmon meticulously retraces its ancestors' exact steps back up its home river, an eel crosses an ocean to breed with any other European eel and its offspring drift to random coasts.

Human knowledge of where eels procreate is based on observations and strong assumptions rather than direct proof. Although science requires empirical evidence and observation rooted in the tradition of Aristotle, no human has ever seen two eels mate or observed a mature eel in the Sargasso Sea.

Johannes Schmidt spent eighteen years sailing back and forth across the Atlantic catching tiny, transparent willow leaves, leading him to that destination.

European and American eel larvae drift together on ocean currents, but European larvae spend three years crossing the ocean while American larvae metamorphose after just one year. Schmidt discovered that American eel larvae grow faster and have fewer vertebrae than European eel larvae, allowing them to break out of the Gulf Stream near the American coast while European larvae continue eastward.

Schmidt placed tiny willow-leaf larvae under a microscope on rolling ships to count muscle fibers along their backs, which correspond to the number of vertebrae in the adult fish.

2. Cultural History and Fishing Traditions

Civilizations throughout history have held radically opposing views on the eel while developing ingenious methods to catch them.

Ancient Attitudes and Taboos

Throughout history, different civilizations held radically opposing views on the eel, treating it either as a sacred demon, an unclean creature, or a delicacy. Ancient Egyptians considered the eel a mighty demon and a forbidden food associated with the creator god Atum. Ancient Romans had mixed opinions, some viewing it as loathsome near sewer outlets and others using live eels in pools to punish slaves.

Archaeologists found mummified eels in tiny sarcophagi next to bronze statuettes of gods in Egypt, and Roman commander Vedius Pollio allegedly fed slaves to eels.

Religious texts like Leviticus codified a dietary taboo against sea creatures lacking visible fins and scales, cementing the eel's status as detestable. Biblical dietary laws dictate that any water creature without fins and scales is abhorrent and detestable to eat. This led to a misunderstanding regarding eels, whose scales are microscopic and covered in slippery slime.

Early American pilgrims were saved from starvation by native gifts of eels, though this role was later erased from national mythology. On November 11, 1620, the Mayflower dropped anchor off Cape Cod with 102 passengers on board. By the following spring, only 53 passengers survived. A member of the Patuxet tribe named Tisquantum taught the surviving colonists how to catch eels by treading them out with his feet and gifting them armfuls of food.

Tisquantum visited the struggling pilgrims and harvested as many eels as he could hold in one hand using his bare feet.

Fishing Methods and Local Knowledge

Traditional and unusual fishing methods like klumma reveal how local knowledge is passed down and how the eel defies expectations. Klumma is an old fishing method in Skåne where anglers thread long strings of worms into a ball without a hook, lower it at night, and pull the eel into the boat based on its clingy bite.

The author and his father used an electrical cord connected to a pitchfork with 220 volts to shock worms out of the ground before going out on a boat to catch twelve eels in one night. Later, they caught fifteen eels during two successive night fishing trips.

To try this traditional method, you can follow specific steps:

• Thread a needle with extra-strong sewing thread and hold it in one hand while holding a worm in the other.
• Stick the needle through the worm, pull the thread through, and repeat until you have several feet of worms.
• Roll the worms into a quivering, stinking ball of slime and secretions.
• Attach a sinker and a line to the ball without using a hook.
• Fish at night from a boat, throw the ball to the bottom, and hold the taut line gently.
• Give an immediate tug when the eel bites and pull it into the boat in one quick motion.

The author and his father also caught eels using primitive fishing lines called spillers instead of standard multi-hook lines. The author's father handmade these spillers by sharpening fifteen-foot thick nylon lines tied to wooden stakes, attaching self-made lead sinkers poured in steel pipes, and finishing with a single hook baited with a worm.

At seven years old, the author helped his father set ten or twelve of these spillers thirty feet apart along a steep stream bank at dusk.

Along Sweden's Hanö Bay, traditional eel fishing is governed by an ancient feudal system of fishing rights and celebrated through local eel feasts and specialized culinary dishes. Eel fishermen operate out of historic wooden eel sheds along a thirty-mile stretch of coast using a trap called a homma, maintaining a distinct cultural heritage rooted in the distribution of rights called åldrätter. The oldest extant documentation regarding åldrätter dates back to 1511, dividing the eel coast into 140 total shares. In 2012, locals established the Cultural Heritage Association of the Eel Coast.

Fishermen prepare catches using recipes such as luad eel, halmad eel, pinna eel, and fläk eel during traditional autumn celebrations called gille.

Basque fishermen in Aguinaga preserve the dying tradition of catching and consuming transparent glass eels as a prized culinary delicacy. The small village contains six hundred residents and five companies that catch and sell glass eels. On cold, rainy winter nights under overcast skies or moonlight, fishermen use round nets on long rods to scoop glass eels from the Oria River as they swim upstream from the Bay of Biscay.

In San Sebastián restaurants, a small 250-gram portion of glass eels fried in olive oil with garlic and chili can cost sixty or seventy dollars.

Eel fishermen around Northern Ireland's Lough Neagh formed a cooperative society to reclaim fishing rights and protect the eel population through restocking projects. Locals have fished for eels around Lough Neagh for at least two thousand years. In 1605, Irish locals were forced to give up fishing rights to English colonizers and later a London merchant consortium called the Ring.

Catholic fishermen formed the cooperative society in 1965 to fight back. They initially bought 20 percent of the fishing rights and later purchased the remaining 80 percent.

The Lough Neagh Fishermen’s Cooperative Society runs an expensive project to buy and release glass eels into the lake to bolster dwindling stocks. Today, fishermen use spillers featuring four hundred hooks on each line set into the water.

3. Scientific Quests and Frustrated Discoveries

Generations of scientists, from Aristotle and Sigmund Freud to Johannes Schmidt, struggled against the eel's refusal to reveal its secrets.

Spontaneous Generation and Freud in Trieste

In the fourth century BCE, Aristotle concluded that eels are born spontaneously out of mud and sediments without parents, eggs, or biological sex. Observing that dried-out ponds suddenly teemed with eels again after the first rain, Aristotle asserted in Historia Animalium that eels spring into existence like a miracle from decomposing vegetation and do not possess reproductive organs.

Carlo Mondini provided the first scientific description of the reproductive organs and eggs of a female eel in 1777. By dissecting an eel caught near Comacchio, Mondini proved that eels possess reproductive organs and produce eggs, finally challenging the centuries-old dogma of spontaneous generation.

Nineteen-year-old Sigmund Freud failed to find the male eel testicles during a grueling research trip to Trieste. Sent by his professor Carl Claus in 1876 to solve the ultimate biological mystery, Freud dissected over four hundred eels in a marine laboratory but found only female reproductive organs, leading to a profound lesson in the limits of science.

Freud wrote letters to his friend Eduard Silberstein from Trieste detailing his stained hands, the haunting dead tissue, and his ultimate confession that all dissected eels belonged to the fairer sex.

The Danish Quest in the Atlantic

Danish marine biologist Johannes Schmidt spent nearly two decades tracing eel larvae across the Atlantic Ocean to discover their birthplace in the Sargasso Sea. Starting in 1904 aboard the steamship Thor, Schmidt gathered specimens from research vessels and freighters, measuring their sizes and counting muscle fibers under a microscope to differentiate between European and American species and track them to their spawning grounds.

Following a visit by Louis Pasteur, the owner of Carlsberg invested in an in-house research laboratory, providing financial support and a scientific foundation for researchers like Johannes Schmidt and his uncle Johan Kjeldahl. Schmidt enlisted twenty-three large freight ships between 1911 and 1914 to trawl for transparent larvae and log more than five hundred catches across the North Atlantic.

Despite decades of expeditions by prominent marine biologists, no living or dead adult eel has ever been found in the Sargasso Sea. Researchers like Friedrich-Wilhelm Tesch and James McCleave conducted multiple expeditions using nets, trawls, and sophisticated acoustic instruments to find spawning eels.

James McCleave and Gail Wippelhauser tried using one hundred hormone-injected female American eels as bait in cages, but ninety-five died before departure, and the remaining five disappeared with their buoys.

A research team tagged seven hundred silver eels with electronic transmitters across Europe. Due to transmitter failures and predation by sharks, only eighty-seven eels provided useful data. The data showed they swam at depths of three thousand feet during the day and rose to warmer surface water at night, taking widely disparate routes that converged around the Azores before heading west.

4. Captivity, Longevity, and Faith

When you prevent an eel from migrating, the creature can suspend its aging process and postpone its final transformation indefinitely. The body adapts to captivity by remaining in a juvenile yellow eel state while growing abnormally large eyes.

When prevented from migrating, eels can live for decades or centuries, and their mysterious resilience fosters a psychological need for faith and myth.

The Brantevik Eel allegedly lived for 150 years sealed inside a farm well in Skåne, Sweden, after being caught by eight-year-old Samuel Nilsson in 1859. When Swedish television visited the farm during a 2009 broadcast, the eel was found to have grown disproportionately large eyes before it was discovered dead in August 2014.

Fritz Netzler caught an eel named Putte in Helsingborg in 1863 and kept it in small tanks. The eel eventually died in the Helsingborg Museum in 1948 at roughly 88 years of age. At the deep bottom of the sea, where normal solar cycles do not apply, biological aging follows entirely different laws. An ocean quahog named Ming, caught off Iceland in 2006, was at least 507 years old, and glass sponges in the Pacific Ocean can live for over 11,000 years.

The Psychology of Belief and Resurrection

In modern literature, the eel frequently serves as a dark, unsettling metaphor for tragedy, death, and the irrational human psyche. Authors like Günter Grass, Fritiof Nilsson Piraten, Boris Vian, and Graham Swift use the eel to foreshadow disaster, represent the subconscious, or link the beginning of life with its demise.

In Günter Grass's The Tin Drum, a fisherman pulls a horse's head out of the sea covered in slithering eels, triggering a psychological repulsion and a self-destructive fish diet in Agnes Matzerath. Sigmund Freud theorized that the uncanny arises when the familiar suddenly becomes unfamiliar, a concept tied to his frustrating eel research in Trieste in 1876.

The seemingly miraculous ability of eels to appear dead out of water and revive when returned to it mirrors the psychological structure of religious faith. An eel found covered in dust and gravel in the garage after five or six hours out of water floated belly up initially before turning over and swimming normally when put back into the bucket. This inexplicable survival fosters a need for mystery, paralleling how humans give up logic and rationality to embrace religious faith, miracles, and the promise of resurrection.

The movement of a dowsing rod is caused by the ideomotor phenomenon rather than any hidden underground forces. Numerous scientific experiments show tree branches cannot locate underground water or metal. Instead, the movement is caused by minute, unconscious muscle movements executed without conscious intent, expressing an idea or preconceived notion.

5. Extinction Crisis and Personal Memory

The Anthropocene and Endangered Eels

The earth is currently experiencing a sixth mass-extinction event, but unlike previous geological extinctions driven by natural catastrophes, this one has a living perpetrator. While past mass extinctions were caused by events like continental drift, cooling, or meteor strikes over millions of years, the current extinction is happening at a vastly accelerated pace due to human activity altering habitats and the atmosphere.

Multiple anthropogenic factors are driving the critically endangered eel toward extinction.

Biologists David Wake and Vance Vredenburg published a 2008 study showing that at least a third of the earth's amphibian species were endangered, leading journalist Elizabeth Kolbert to document widespread species loss in her 2014 book The Sixth Extinction. The European eel is categorized as critically endangered by the IUCN because its population has collapsed catastrophically. Because mature eels cannot be counted at their unknown spawning grounds in the Sargasso Sea, the IUCN assesses the species primarily through the steep decline of newly arrived glass eels in Europe. Reliable counts indicate that newly arrived glass eels in Europe have plummeted to only about 5 percent of what they were at the end of the 1970s.

Human activities introduce pathogens like herpes virus anguillae and nematodes, toxic industrial chemicals that impede migration, dams that kill migrating fish via turbines, and intense glass eel harvesting. A 2013 study in South Carolina showed that 30 percent of glass eels carried the nematode parasite Anguillicoloides crassus, which attacks the swimming bladder. Historical animal extinctions like the dodo and Steller's sea cow demonstrate how defenseless endemic species can be rapidly exterminated by humans. Steller's sea cow was discovered by Georg Wilhelm Steller in 1741 during Vitus Bering's expedition and was hunted to total extinction by Russian hunters just twenty-seven years later.

Management plans and fishing restrictions implemented by the European Union have failed to reverse the decline of the eel population. In 2007, Sweden's National Board of Fisheries banned general eel fishing except for professional permit holders, while subsequent EU ministerial quotas repeatedly delayed comprehensive bans. To protect the remaining stocks, you must follow strict conservation rules:

• Ensure that at least 40 percent of all silver eels can reach the sea by limiting fishing and building alternative passes to circumvent dams and power stations.
• Set aside at least 35 percent of the catch of glass eels for reintroduction into the wild.

Father, Son, and Final Memories

The author reflects on his changing relationship with his father, marked by shared eel fishing trips, unspoken family origins, and his father's fatal illness. As you grow older and observe terminal illness, you realize that mortality brings a complex mixture of grief, memory, and unresolved questions. As the author grew up and attended university, he and his father drifted apart, yet they continued fishing for eels and visiting a cabin, even as his father suffered from terminal cancer caused by asphalt exposure.

The author's mother revealed during his father's hospitalization that his father's biological father had abandoned the family, a riddle of origin that his father chose to resolve by embracing the stepfather who raised him. Scientific observations suggest that the moment of death involves complex neurological states rather than an instantaneous cessation of life. Intensive care physician Lakhmir Chawla observed increased brain activity for thirty seconds to three minutes after the heart stopped beating in over a hundred dying patients.

10 Key Ideas

1. The European eel undergoes drastic morphological transformations, shifting from transparent leptocephalus larvae and glass eels to muscular yellow eels and finally silver eels.
2. The origin of the European eel remained a biological puzzle for millennia before scientists traced its birthplace to the deep, algae-covered waters of the distant Sargasso Sea.
3. Throughout history, different civilizations held radically opposing views on the eel, treating it either as a sacred demon, an unclean creature, or a delicacy.
4. Traditional and unusual fishing methods like klumma and spillers reveal how local knowledge is passed down and how the eel defies expectations.
5. In the fourth century BCE, Aristotle concluded that eels are born spontaneously out of mud and sediments without parents, eggs, or biological sex.
6. Nineteen-year-old Sigmund Freud failed to find the male eel testicles during a grueling research trip to Trieste, leading to a profound lesson in the limits of science.
7. Danish marine biologist Johannes Schmidt spent nearly two decades tracing eel larvae across the Atlantic Ocean to discover their birthplace in the Sargasso Sea.
8. When you prevent an eel from migrating, the creature can suspend its aging process, postpone its final transformation indefinitely, and live for decades or centuries.
9. The seemingly miraculous ability of eels to appear dead out of water and revive when returned to it mirrors the psychological structure of religious faith.
10. Multiple anthropogenic factors, including pathogens, toxic chemicals, hydroelectric dams, and intense harvesting, are driving the critically endangered eel toward extinction.