Saturday, November 22, 2014

American Eel

I recently related how I discovered the elver stage of the American Eel in a local stream I had been exploring. I thought I would do a blog on eels because they are more interesting than you might think.

Eels are a catadromous species. We are more familiar with anadromous species, such as the rockfish which travel from salt water to fresh to reproduce. A catadromous species travels from freshwater to salt water to reproduce. Until very recent times, it was not known where or how eels reproduced. They are considered to be a fish and have scales so minute, most people don't realize they have them.

The elvers I saw are actually the third stage of the life cycle of an eel. Life begins in a great spawning event of all adult eels in the Sargasso Sea, located in the middle of the Atlantic Ocean. The eggs drift slowly towards the coast, transforming into a stage known as leptocephali. It is a larval stage looking much like a leaf. As the eels near the continental shelf, they transform into glass eels containing little pigment. As they near coastal streams and rivers, they enter the next stage of life which is the elver stage I saw in the stream.

Elvers become yellow eels over the course of the next fifteen to twenty-five years during which they attain adult size.

This photo shows an adult eel my brother was unlucky enough to catch a couple of summers ago while he was fishing in the Patuxent. He accidentally got some of it's slime on his shoe which never did come off, even after a couple of years. He also nicked himself. That isn't eel blood.

Yellow eels become silver eels in the final stage of their life cycle. The changes they go through at this point are astounding, but are too involved to detail here.

The last time I was at the Patuxent filming, the river was dotted with buoys. I thought they might be crab pots, but it seemed a little late to still be crabbing.

After a while, a commercial fisherman appeared and began pulling up the pots. Once I saw them, I realized they were eel pots. It was hard to tell if he had any luck catching them.

He continued to pull up pots over the next couple of hours from the stretch of river out in front of me as I reflected on what a hard living that has to be. I hope he was at least enjoying the scenery. As usual the adult eagles were in the trees watching. They also have white heads like the lepto (white) cephali (head) stage of the eels.

Eels are an endangered species, mostly as a result of damming rivers, which prevents them from migrating to the stream environment they require to reach adulthood. While Americans mainly use eels as bait to catch other species, some European and Asian countries consider them a delicacy, so there is continual pressure on the species even here in the U. S., where they are harvested and shipped overseas.

There is a lot more to learn about this complex species than I can relate here, but if you are interested, I would encourage you to google the words "American eel" and "Wikipedia" and explore them further.

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