Top 2 Dangerous Fishes in the World
Described as something of “an underwater Audubon,” James Prosek has always had a particular fondness for marine life—the trout, billfish, and other fishes that are part of the fresh and saltwater ecosystems covering much of the globe. He has dedicated years to studying and writing about these water worlds and the diverse creatures which inhabit them. Prosek’s latest adventure centers around the eel, a migratory fish (it’s not a snake) that continues to leave scientists puzzled. In his book, Eels: An Exploration, From New Zealand to the Sargasso, of the World’s Most Mysterious Fish, Prosek travels in an effort to unravel the mystery of the eel; to better know its habits and life cycle (to-date no one has witnessed eels spawning in the wild), as well as explore the creature’s complex and varied relationships with humans. Read an excerpt:
Eels: An Exploration, From New Zealand to the Sargasso,
of the World’s Most Mysterious Fish
Conjecture about what an eel is exactly, or where its place is in the tree of life, has racked the brains of more than a few naturalists. Its limbless elongated body led some to believe it was related to the snake. The Greek naturalist and poet Oppian wrote in the second century A.D.: “Nothing more is known, than what people repeat about the loves of Roman eels and snakes. Some say that they pair, that, full of eagerness, drunk with desire, the Roman eel comes out of the sea to go and meet her mate.” As late as 1833 Jerome V. C. Smith wrote in his Natural History of the Fishes of Massachusetts: “On the whole, we view the eel in the light of a water-serpent, being the connecting link between purely aquatic and amphibious reptiles.” The eel, however, is a fish, though it is a fish like no other.
The freshwater eel, of the genus Anguilla, evolved more than fifty million years ago, giving rise to fifteen separate species. Most migratory fish, such as salmon and shad, are anadromous, spawning in freshwater and living their adult lives in salt water. The freshwater eel is one of the few fishes that does the opposite, spawning in the sea and spending its adulthood in lakes, rivers, and estuaries—a life history known as catadromy (in Greek ana-means “up” and cata- means “down,” that prefixes suggesting the direction the fish migrates to reproduce). But among caradromous fishes, the eel is the only one that travels to the depths of the oceans so far offshore.
“Salmon,” Mike Miller, an eel scientist, told me, “can imprint on a river system. They are born in the river system, they go out in the ocean, and they come back to the same river—it’s not that bloody hard to do. In the case of the eel, you’re born in the open ocean. You can’t see anything around you except blue water. It’s just blue water until they come to the coastal areas, where they first enter estuaries and streams at random. And then, ten to thirty years later when they leave the river, they have to swim all the way out to the same place in the ocean again. And how do they do that?”
Wherever eels are born, they’re relentless in their effort to return to their oceanic womb. I can tell you this from personal experience because I’ve tried to keep them in a home aquarium. The morning after the first night of my attempt, I found eels slithering around the floor of my kitchen and living room. After securing a metal screen over the tank with heavy stones, I was able to contain them, but soon they were rubbing themselves raw against the screen. Then one died trying to escape via the filter outflow. When I screened the outflow, they banged their heads against the glass until they had what appeared to be seizures and died. That’s when I stopped trying to keep eels.
Eels are wondrous in their ability to move. They’re often found in lakes, ponds, and postholes with no visible connection to the sea, leaving the inquisitive shaking their heads. On wet nights, eels are known to cross over land from a pond to a river, or over an obstruction, by the thousands, using each other’s moist bodies as a bridge.Young eels can climb moss-covered vertical walls, forming a braid with their bodies. Farmers in Normandy say that eels will leave rivers on spring nights and find their way to vegetable patches to feed on peas.
The yearly journeys of millions of adult eels make from rivers to oceans must be among the greatest unseen migrations of any creature on the planet. In the course of these journeys, which span thousands of miles, eels face a long list of dangers: hydroelectric dams, river diversions, pollution, disease, predation (by striped bass, beluga whales, cormorants, among others), fishing by humans, and changes in ocean currents or temperature structure due to global warming, which may confound eels during their migrations.