An eel ladder is type of fish ladder

Fish ladder

A fish ladder, also known as a fishway, fish pass or fish steps, is a structure on or around artificial barriers to facilitate diadromous fishes' natural migration. Most fishways enable fish to pass around the barriers by swimming and leaping up a series of relatively low steps into the waters on...

 designed to help eel

Eel

Eels are an order of fish, which consists of four suborders, 20 families, 111 genera and approximately 800 species. Most eels are predators...

s swim past barriers, such as dam

Dam

A dam is a barrier that impounds water or underground streams. Dams generally serve the primary purpose of retaining water, while other structures such as floodgates or levees are used to manage or prevent water flow into specific land regions. Hydropower and pumped-storage hydroelectricity are...

s and weir

Weir

A weir is a small overflow dam used to alter the flow characteristics of a river or stream. In most cases weirs take the form of a barrier across the river that causes water to pool behind the structure , but allows water to flow over the top...

s or even natural barriers, to reach upriver feeding grounds. (Many eels are catadromous

Fish migration

Many types of fish migrate on a regular basis, on time scales ranging from daily to annually or longer, and over distances ranging from a few metres to thousands of kilometres...

, living in fresh water but spawning

Spawn (biology)

Spawn refers to the eggs and sperm released or deposited, usually into water, by aquatic animals. As a verb, spawn refers to the process of releasing the eggs and sperm, also called spawning...

 at sea.) The basic design of an eel ladder has the eel swim over the barrier using an eel ascending ramp, which provides the eels a climbing substrate to "push against" while slithering upstream. For some higher barriers, elevator

Elevator

An elevator is a type of vertical transport equipment that efficiently moves people or goods between floors of a building, vessel or other structures...

-style systems are also used.

An eel ladder typically consists of four parts: an eel ascending ramp, a supporting structure, a water-feeding system, and a side gutter. The side gutter provides an attraction flow to draw eels toward the ladder, the water-feeding system ensures the proper flow of water to the gutter and the ramp, and the supporting structure mounts the ladder to the barrier.

The eel ascending ramp can be a fairly simple constructions, such as a hollowed out tree filled with recycled

Recycling

Recycling is processing used materials into new products to prevent waste of potentially useful materials, reduce the consumption of fresh raw materials, reduce energy usage, reduce air pollution and water pollution by reducing the need for "conventional" waste disposal, and lower greenhouse...

 fishing net

Fishing net

A fishing net or fishnet is a net that is used for fishing. Fishing nets are meshes usually formed by knotting a relatively thin thread. Modern nets are usually made of artificial polyamides like nylon, although nets of organic polyamides such as wool or silk thread were common until recently and...

, or a more complex structure designed to accommodate specific species or ages of eels.

External links

• Fish-Pass sarl eel ladder and elevator systems
• Dwight St. Dam Eelway project (Chicopee River
  Chicopee River
  The Chicopee River is an tributary of the Connecticut River in Metropolitan Springfield, Massachusetts, known for fast-moving water and its extraordinarily large basin: the Connecticut River's largest tributary basin...
  
  , Massachusetts
  Massachusetts
  The Commonwealth of Massachusetts is a state in the New England region of the northeastern United States of America. It is bordered by Rhode Island and Connecticut to the south, New York to the west, and Vermont and New Hampshire to the north; at its east lies the Atlantic Ocean. As of the 2010...
  
  )