The Book of Eels, Patrik Svensson [bill gates best books .TXT] 📗

should be said that there is no consensus on how significant it would really be to find a mature eel in the Sargasso Sea. Some scientists feel it’s beside the point, since we already know that’s where the eels are going. Others claim our knowledge of the eel’s life cycle can’t be considered complete until someone has observed an eel at its spawning ground. To these scientists, the elusive eel is something of a scientific holy grail.

In the past few decades, some researchers, such as James McCleave, have started asking another difficult question: If we can’t track all silver eels back to their birthplace, and in fact not even a single one, can we really be completely certain the eel breeds only in the Sargasso Sea? Granted, it took Johannes Schmidt almost twenty years to find the smallest of the tiny willow leaves there, but he had searched only a fraction of the world’s oceans. Schmidt himself wrote in 1922 that until all the seas have been trawled for eel larvae, it would be impossible to say for certain where the eel breeds, or at least where all eels breed. And virtually all eel expeditions since, including James McCleave’s, have focused on the already familiar region of the Sargasso Sea. Perhaps some eels go elsewhere entirely? It’s unlikely, but how can we know for certain?

Moreover, the Sargasso Sea is very large. Is it one big breeding ground, or are there several separate breeding grounds within its borders? Do the American and European eels breed in exactly the same area, or do they prefer different locations? Some scientists, Friedrich-Wilhelm Tesch among them, have claimed that the American eel breeds in the western part of the Sargasso Sea while the European one stays farther east, but that the areas are partially overlapping. Others argue the collected leptocephalus larvae do not support such conclusions. All we know for sure is that when the tiny, transparent willow leaves leave the Sargasso Sea, European and American ones are intermingled, drifting helplessly along in the mighty ocean currents, while their parents appear to remain, die, and decompose.

HENCE, TO THIS DAY, THE WORLD’S LEADING ZOOLOGISTS AND MARINE biologists, the people who are most intimately familiar with the eel, are forced to qualify their reports and results with reservations. “We believe,” they’re obliged to say. “The data indicate . . .”; “It can be assumed that . . .” By patiently rejecting less likely scenarios, they are slowly moving toward a probability that in turn closes in on truth.

It can, for example, be assumed that what’s true of one of our eel’s closest cousins, the Japanese eel, is also true of the European eel. And when it comes to the Japanese eel, some of the classic aspects of the eel question are, in fact, slightly less enigmatic.

The Japanese eel, Anguilla japonica, looks essentially like its European counterpart. Its life cycle is also very similar. It hatches in the sea and drifts toward the coast as a willow leaf. It turns into a glass eel and wanders up waterways in Japan, China, Korea, and Taiwan. It becomes a yellow eel and lives out its life in fresh water before many years later turning into a silver eel and wandering back out into the sea to spawn and die. It’s a very popular fish for cooking, particularly in Japan, and it has long played an important role in East Asian culture and mythology, among other things as a symbol of fertility.

When it comes to the question of procreation—where and how it happens—the Japanese eel was long an even bigger mystery than the European one. Scientists were able to pinpoint its spawning ground only in 1991. Employing the same method and dedication as Johannes Schmidt, though not taking quite as long, the Japanese marine biologist Katsumi Tsukamoto sailed around the sea with nets and instruments, searching for increasingly minute leptocephalus larvae. One autumn evening in 1991, he finally managed to find specimens that were only days, or perhaps hours, old. It was far out in the Pacific Ocean, just west of the Mariana Islands.

After this discovery, it wasn’t long before an even more sensational discovery was made. In the autumn of 2008, a research team from the Atmosphere and Ocean Research Institute in Tokyo actually managed to catch fully grown Japanese eels in exactly the area west of the Mariana Islands where the findings situated the breeding area. One male and two females were caught. All three had already spawned and were in bad shape. They died shortly thereafter. But this meant the Asian version of the holy grail of science had at long last been found.

But what did that mean? According to at least one member of the expedition, Michael Miller, nothing, really. It didn’t prove anything we didn’t already know. We already know approximately where they breed. But we still don’t know exactly where, how they get there, or how many of them are successful. We still haven’t seen them procreate. We don’t know why. Why, why?

MYSTERIES HAVE AN ALLURE OF THEIR OWN, BUT THERE ARE SOME things that suggest the timeless eel question will eventually be answered. Not only have silver eels been found after breeding in the Pacific, but researchers there have also pulled off what no one has managed with the European or American eel. They have successful bred the Japanese eel, Anguilla japonica, in captivity. As early as 1973, scientists working at the University of Hokkaido were able to extract eggs from sexually mature female eels, inseminate them artificially, and have them hatch and become larvae. The future of the threatened eel was not their primary concern; the venture had rather narrower economic motivations. The eel is vastly popular on Japanese dinner tables and the subject of a multimillion dollar industry. If it could be farmed, the way salmon is, for instance, it would mean a lot more eel at a fraction of the cost. Consequently, the market is prepared to invest large sums in research that could make farming possible.

Unsurprisingly,