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.
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