I love eels. Even if many people think eels are slimy and gross, they are some of the coolest looking aquatic creatures living in our local waters. Not snakes at all, eels are fish that have fins and can breathe underwater with gills instead of lungs.
While throwing a casting net a few days ago along the edge of the Navesink River in Middletown Township, New Jersey to see what might be swimming towards the end of October, I had the pleasure of finding a single American Eel among the spartina grasses. As hard as I tried, it wasn't exactly easy picking up an eel. They cover their entire bodies with a slick mucous layer, making them nearly impossible to capture by hand. The old saying “slippery as an eel” is more than just a figure of speech.
Yet, I learned a trick from a fisherman in Asia many years ago to use your middle finger to grip the eel at a spot about 1/3 of the way down its body. This time, it seemed to work for me, it not always does though.
This critter was just a little eel, about 8 or 9 inches in length. It might have only been a few years old. Adult American Eel males can grow to three feet long and adult females can grow up to five feet long.
Yet this petite sized eel was quite eye-catching. It had a greenish-yellow hue on its back with a stark white belly and protruding bloodshot eyes. Perhaps it was under a bit of stress as it was in all likelihood moving upstream from brackish waters to freshwater to spend the winter. Once the eel found a favorable spot, it would burrow into mud or under rocks or a log. Once spring would arrive, the little eel might return to the shallow brackish waters of the estuary or perhaps choose to live out most of its life in freshwater.
Not all eels will migrate to freshwater for the winter, some will remain in salty rivers and bays to spend the winter. What triggers some eels to migrate inland and others do not is still a mystery, though it might have something to do with food resources. According to the U.S. Fish & Wildlife, many people once thought that male eels remain in the estuarine waters and only females swim upstream to freshwater, however, territories for eels may be determined by density. "Where eels are more densely concentrated, they are more likely to be males, while eels living less densely are more likely to be females." Changes of habitat tend to occur only during transitional periods such as in spring and autumn. Some juvenile eels travel to overwintering sites if their summer habitat is unsuitable.
Where exactly this little American Eel was going was anyone's guess. The river temperature was in the low 50 degree F. range. Chilly waters for sure, winter was not far away. Wherever the eel was going, hopefully it would get there soon. .
I had brief release ceremony, then watched the slimy little eel slither over pebbles and gravel to revisit the water. American eels are amazing creatures. They can actually absorb oxygen through their skin, just like many amphibians, as well as their gills, making it possible for eels to travel over land, particularly in wet grass or mud, which may help them move around barriers in the water. They can slide over rocks, dams, wet grass and other seemingly impassable obstructions to reach their destination.
The American Eel also has an amazing life cycle. Eels are catadromous, meaning they live in freshwater rivers and spawn in the ocean. Eels are the only native catadromous fish in New York Harbor.
The little eel I caught was almost certainly what many wildlife or fish biologists would call a "yellow eel." Before American Eels mature, they become yellow eels, which are sexually immature adults that are yellow-green to olive-brown in color on their backs. In their yellow phase, American Eels are nocturnal, swimming and feeding at night on worms, small fish, clams and other mollusks, crustaceans and even dead animal matter.
After 5 to 40 or more years of living in freshwater or brackish waters the yellow eels begin to sexually mature to become "silver eels.". Eels that remain in estuarine waters undergo the same changes but mature earlier than those in freshwater. Silver eels are American eels that have undergone physical changes to prepare themselves for a long journey near the middle of the Atlantic Ocean to spawn.
It starts in October, when the eels prepare themselves for their long ocean voyage. They change their coloration of the yellow eel phase to black and white, so they will blend in better with shadowy waters. Their eyes also enlarge to help the eels see better while traveling in deep, dark ocean waters. Sometime in January, after weeks of swimming thousands of miles, the eels will finally spawn in the Mid-Atlantic, somewhere in the Sargasso Sea southeast of Bermuda. Exactly where and how this is done is still a mystery.
After spawning, the adult eels will die. Their eggs will hatch into larvae and will drift with the Gulf Stream for 9 to 12 months. During this time, the larvae will transform to the “glass eel” stage. Ocean currents carry these transparent glass eels thousands of miles to arrive at their U.S. freshwater streams and estuarine habitats. Before entering waterways from the ocean, though, the glass eels will become pigmented. These brown eels, called elvers, are only about two to three inches long. After a few months, the elvers transform into the juvenile “yellow eel” stage.
There are not many fish that have such an elaborate, complex, and enigmatic life cycle like the American Eel. Unfortunately, one of the mysteries of the American eel is their population status. Is the population in decline or stable? It really depends on who you talk to. Some scientists will say the American Eel is in serious decline since the mid-1990s, especially in its northern habitat. On the other hand, the U.S. Fish and Wildlife Service and the National Marine Fisheries Service in 2007 reviewed the status of the American Eel and found at that time that Endangered Species Act protection for the American Eel was not warranted. Some local declines in population had not put the overall population in danger of extinction. The U.S. Fish and Wildlife Service, however, is working with various scientific organizations to better understand and conserve this species.
Certainly more research is needed. It doesn't help the American Eel population when lots of people harvest this fish for bait or food to the point of near collapse. The commercial harvest of eels in America is largely exported to Europe and Japan, where the fish are smoked, jellied, or cooked as a tasty delicacy. Dams also block eel migration routes while turbines kill individual eels. Moreover, changing environmental and climatic conditions connected to global warming threaten their ancestral habitat.
It's not easy being an American Eel. Lucky for me the little eel I found was still alive, though a little stressed, it was able to swim away, headed to an overwintering site somewhere nearby. I wished the little yellow eel well and a long, happy life as it slithered back into the tidal waters of the Navesink River.
To read more about the fascinating life history of the American eel, please read James Prosek's book entitled, Eels: An exploration, from New Zeeland to the Sargasso, of the world's most mysterious fish. Published by HarperCollins books.
For more information, pictures and year-round sightings of wildlife in or near Sandy Hook Bay and Lower New York Bay, please check out my blog entitled, Nature on the Edge of New York City at http://www.natureontheedgenyc.com
