Creature Feature Bronx River Introduction

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Creature Feature

Could you climb up that?

No? Don't feel bad, neither can most fish. In fact these waterfalls may be the reason that almost no migrating fish live in the Bronx River.

But there is an exception: the American eel. This catadromous fish comes all the way from Bermuda and makes its way up the Bronx River to spend most of its life in the headwaters.

The eel can climb around the waterfalls. This makes it the only fish that swims up and down the full length of the river.

It climbs the river in an early stage of life when it's known as a glass eel. (It's called this because of the see-through quality of its skin, which lacks the pigment it will later develop.)

In this state the eel can climb wet surfaces vertically, clinging by the stickiness of the slime that covers its scales.

It can easily get over low dams and other structures by briefly or partially exiting the water, finding a moist, often rocky surface, and then climbing up.

While none of the dams and waterfalls in the Bronx River stop eels from using the Bronx River some large hydropower dams do prevent even eels from navigating those rivers.

American Eel Life Cycle

1.		Eggs are fertilized in Sargasso Sea around Bermuda.
2.		Eggs are carried north by currents.
3.		Eggs turn into larvae [picture on left], which settle into the muddy area at the entrance of a fresh water river where it will spend most of its life (up to 15 or so years).
4.		Larvae metamorphose into glass eels [middle picture], which are small and sticky and able to climb up slippery vertical surfaces, enabling them to navigate many dams (but not major hydro-power dams).
5.		Glass eels begin up-river migrations in early spring.
6.		Glass eels turn into elvers. This happens either during their upstream push or around the time they reach the headwaters where they will stay for years.
7.		Mature eels [picture on right] spend many years in the headwaters. Females grow much larger than males because the eggs they hold are much larger than the sperm contained by the males.

#4. Find a creature that depends on your watershed for habitat. Explain what part of its life cycle it spends in your watershed and how it uses your land and water. If it faces threats, note those down.