An Interesting book about Eels
We have recently moved from Stockholm to London. During this transition time, I had a chance to read a natural history book that I think you might enjoy. The author is Swedish and the topic of the book is a fish of cultural and culinary significance to Swedes. This fish has been a favorite catch in the summer fishing tradition and historically it had a key place on the traditional Swedish Christmas holiday menu. But, no longer.
The European eel is a mysterious and iconic fish, whose population has gone through a rapid decline over the last few decades due to human activities, such as overfishing and environmental degradation of different kinds. I have memories of smoked eel as a delicious part of the Christmas smorgasbord, next to various types of pickled herring. But, today eel fishing is highly regulated and only fishermen with a special license can fish for them.
In the book, The Gospel of the Eels, Patrik Svensson not only summarizes what has been written about the European eel, but also describes our continued deep ignorance of crucial aspects of their life cycle. As a biologist with an undergraduate degree in fish physiology, I was amazed to learn that no one has ever seen adult eels mating, or even observed adult eels on their assumed breedings grounds in the Sargasso Sea.
The book covers the long history of human fascination with eels starting with Aristotle and including Sigmund Freud and Rachel Carson. It is written from the perspective of a lifelong fascination that started with the author fishing for eels with his father. It shows what we know about eels, but more importantly what we don’t know.
After the eel larvae hatch in the Sargasso Sea they eventually end up in European waters. There they swim up into various freshwater ecosystems where they can spend up to 50 years hidden without ever being seen, as they hunt at night and rest during the day. Eventually they will return all the way back to the Sargasso Sea, or so it appears, to reproduce and then die.
To be able to handle the change from a fresh-water to a salt-water environment during the return back to the Sargasso Sea, some 5,000 km away, the whole digestive system is dissolved, presumably to minimize salt uptake. The energy for the return is provided by stores of fats and oils in the muscle tissues, making the eel a favorite meal for many predators including humans. There are also parts of Europe where huge quantities of glass eels, considered a delicacy, are caught as they enter various freshwater systems.
So between the holes in our knowledge about crucial parts of its biology, the impact of overfishing, as well as environmental destruction and climate change, it is, perhaps, no surprise that this animal is considered threatened. This book is one of those books that can help people consider their own impacts on nature and perhaps reconsider some of their everyday actions. Reading this book has renewed my commitment to increasing the protections for marine species and to increasing awareness of the simple actions that we can all take to improve the state of our ocean.