Nearly everyone knows about the epic travels of salmon. Baby fish emerge from eggs laid in submerged gravel beds, sometimes hundreds of miles from the ocean. Tiny fish swim downstream to saltwater, where they spend years growing before returning to their natal stream to mate and die, re-fertilizing the sterile waters for the next generation of salmon. A fish, like salmon, that mostly lives in the ocean but migrates upstream to spawn in fresh water is called anadromous.
There is another type fish equally amazing in its journey that travels in the reverse — from the ocean to fresh water — the eel. Most Iowans would be astonished to learn that American eels are a native fish. Baby eels hatch in the Sargasso Sea, a region of the Atlantic Ocean east of Bermuda. Tiny eels make their way to estuaries, where males stay and grow to about two feet long. Females keep going and swim up large rivers to spend anywhere from five to 20 years growing to four or five feet long on a diet of fish and invertebrates.
At first glance, long, skinny eels look snakelike but are true fish, unrelated to reptiles. They are most common closer to the Atlantic and Gulf Coasts, but the entire state of Iowa is within their possible range. Eels are considered a desirable food fish in places where they are commonly caught, and a similar species is an expensive delicacy in Europe. Eels are rare in the Cedar and Iowa Rivers, but every once in a while, a surprised angler lands one.
Unlike salmon, eels are catadromous, meaning they live most of their lives in freshwater but return to the ocean to spawn. Much about eels is unknown and mysterious. It is likely adults die after spawning. Little is known about them in Iowa, but dams have probably reduced their abundance by blocking migration.
It’s amazing to consider that an Iowa fish that makes its home in our state’s major rivers embarks on a journey as epic as that of the better known salmon.
l Marion Patterson is an instructor at Kirkwood Community College. Rich Patterson is the former executive director of Indian Creek Nature Center in Cedar Rapids. They blog at Windingpathways.com.