08-02-2004, 03:32 PM
American Eel
![[Image: ae.jpg]](http://i.timeinc.net/fieldstream/images_small/ae.jpg)
EEL, AMERICAN Anguilla rostrata.
EEL, EUROPEAN Anguilla anguilla.
Other names for American eel: silver eel, Atlantic eel, common eel, yellow-bellied eel, freshwater eel, bronze eel, water snake, whip; Dutch: amerikaanse aal; Finnish: amerikanankerias; French: anguille d’Amerique; Italian: anguilla americana; Japanese: unagi; Portuguese: enguia-americana; Spanish: anguila, anguila americana; Swedish: amerikansk al.
Other names for European eel: silver eel, common eel, yellow eel, freshwater eel; Dutch: aal; Finnish: ankerias; French: anguille, anguille d’Europe; Italian: anguilla; Japanese: unagi; Portuguese: eiró, enguia; Russian: retschnoi ugor; Spanish: anguila, anguila europea; Swedish: al.
The American and European eels are member of the Anguillidae family of freshwater eels. They are common and have been the object of many wild tales speculating on the nature of their existence. Aristotle was convinced they rose spontaneously from mud, while Roman scholar Pliny the Elder believed young eels came from bits of skin that adult eels rubbed off on rocks. Italian fishermen believed that eels mated with water snakes. The most common hypothesis was that eels arose spontaneously from horse hairs that fell in the water. These many ancient theories likely occurred because of the mystery and complexity surrounding both fish; their spawning habits and many diverse growth changes are among the most unique of freshwater fishes.
These eels are preyed upon by many species at different stages of their existence. They are important forage for such larger offshore predators as sharks, haddock, and swordfish; for inshore species like striped bass; and for many species of birds, including bald eagles and various gulls. Their greatest predator, however, is likely man.
The American and European eel have been prized as food since ancient times and are caught in eel traps and nets, as well as by hook and line and spearing. They are intensively sought commercially in many places and considered a delicacy, especially in Europe and Japan. Eels of all sizes are desirable for consumption, although larger individuals, having spent many years on the bottom of lakes and rivers and being high in fat content, may be especially susceptible to elevated levels of contaminants in areas that are highly polluted.
Larger individuals (10 to 16 inches or so) are used as bait by anglers, especially those seeking big striped bass, and they may be sold as fish bait in coastal shops. Smaller individuals are also sold by commercial interests for consumption, and have been known to fetch many hundreds of dollars per pound. Increased coastal netting of small eels due to rising market demands has raised concerns about the exploitation of these fish. European and Asian stocks have been especially diminished, and North American stocks have likewise been under severe pressure. Elvers have been harvested for use in pond culture and aquaculture operations. They have also been caught and transplanted to inland waters to boost or establish eel stocks.
Identification. The body is elongate and snakelike with a pointed head and many teeth. It is covered with thick mucus, hence the term "slippery as an eel." The large mouth extends as far back as the midpoint of the eye or past it. There is a single gill opening just in front of the pectoral fins. There are no pelvic fins, and the soft-rayed dorsal, anal, and caudal fins form one continuous fin. There are no visible scales. Coloring changes with maturity, as described later in this text.
The American and European eels are almost identical; they can be distinguished only by counting vertebrae. The adult American eel has 103 to 111 vertebrae, whereas the European has 110 to 119.
Size/Age. American eels are able to reach 50 inches and 16 pounds. The average size for adult females is about 3 feet while adult males are considerably smaller, rarely growing more than a foot long. They can live longer than 9 years in rivers, streams, and lakes. European can achieve similar size and age, but are usually found smaller on average.
Distribution. The American eel occurs from southwest Greenland to Labrador, south along the North American coast to Bermuda, the Gulf of Mexico, Panama, and the Carribean islands. Withing this region inland it occurs from the Mississippi River drainage east, and northeast to the Great Lakes and to the Atlantic Ocean.
The European eel occurs in drainages feeding the North Atlantic, Baltic, and Mediterranean Seas, and along the east coast of Europe from the Black Sea to the White Sea. It has been introduced to Asia and South and Central America, but has not reproduced.
Habitat. These eels are catadromous, spending the majority of their life in freshwater and returning to saltwater to spawn. They prefer to dwell in heavy vegetation or burrow in the sandy bottom. Their physical structure is such that they can easily swim backward and dig tail first into soft bottom sediments.
Life History/Behavior. When it comes time to spawn, the males and females stop feeding, change in color from olive to black, and move out to sea. Both the American eel and European eel spawn in the same area of the Atlantic Ocean, in deep water at the north edge of the Sargasso Sea. There each female lays as many as 10 to 20 million eggs, and both sexes die after spawning.
The eggs float to the surface and soon hatch into slim, transparent larvae (glass eels). The sex an eel becomes is thought to be partly determined by environmental conditions such as crowding and food abundance, but is not determined until they are about 8 to 10 inches long in their freshwater habitat.
The larvae drift and swim for one year (American) or three years (European) with ocean currents toward river mouths. Males stay near the mouths of rivers while females travel upstream, mostly at night. Eels can absorb oxygen through their skin as well as gills, and are known to travel over land, particularly in damp, rainy weather. Balls of intertwined eels have been seen rolling up beaches in search of freshwater for overwintering.
Distinctive terms are used to identify these eels in size, coloring, and behavior at different stages of their lives. They are as follows:
Glass eels are those in the young larval stage called leptocephalus; they are shaped like willow leaves and have ribbon-like transparent bodies with a distinct black eye. These range from approximately 1 to 2.5 inches in length, and are attracted to coastal estuaries and freshwater, where they are the target of intense commercial fishing interest.
Elvers are small eels in the stage of adapting to freshwater. They range from 2.5 to 3.5 inches in length, and are darker in color than glass eels, being fully pigmented and ranging from gray to greenish brown. Mass upstream migrations of elvers have been observed. Though inconspicuous as they swim along river bottoms, they are very visible when they encounter obstructions like dams and waterfalls.
Yellow eels are growing eels that exist in freshwater. Some biologists refer to them as adults while others refer to them as subadults. In any event, they are sexually immature, and yellowish to olive-brown on the back and lighter on the belly. They swim freely along river bottoms, through shoreline rock crevices, and into silty lake bottoms in search of prey.
Silver eels are sexually mature adults that are dark with a bronze-black hue on the back and silver on the underside. Many have enlarged eyes, which is believed to give them better vision in the ocean. These are fish that are ready to migrate, or in the process of migrating, out of freshwater to their ocean spawning grounds, a process that is believed to take three to five months through the fall and winter.
Food. The diet of the nocturnal feeding American and European eels includes insect larvae, small fish, crabs, worms, clams, and frogs. They also feed on dead animals or on the eggs of fish, and are able to tear smaller pieces of food that are too large to be swallowed whole.
The feeding process on food that is large is rather unusual. These eels have relatively weak jaws that are mainly suited to grasping, yet they possess many small, round, and rather blunt teeth Because they are palindromic, meaning that they can move equally well forward or backward forcefully, they are able to pull, twist, and spin when tearing apart prey that is too large to be consumed whole. The habit of spinning, which also occurs when they are caught by anglers (with some consternation about line twist and grasping), deserves explanation.
Spinning Habits. When food cannot be consumed whole, or when it cannot be broken into swallow-size morsels by jerking and pulling, an eel spins at a dizzying rate. Researchers have recorded a rate of six to fourteen spins per second (Olympic ice skaters can spin five times per second). The purpose of this is to break apart food into sizes that can be consumed; that size is determined by the width of its mouth, which is said to seldom exceed 2 inches. It also serves the purpose of gaining access to interior portions of food items, such as entering the body cavity of a dead fish to consume its eggs.
The habit of spinning, however, is also one that brings attention to the eel itself. Eels may spin several times in a row for a protracted period, during which they are less alert to predators and more vulnerable. This tendency may in part account for some of the effectiveness of wavy and spinning lures and bait rigs in sportfishing applications.
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EEL, AMERICAN Anguilla rostrata.
EEL, EUROPEAN Anguilla anguilla.
Other names for American eel: silver eel, Atlantic eel, common eel, yellow-bellied eel, freshwater eel, bronze eel, water snake, whip; Dutch: amerikaanse aal; Finnish: amerikanankerias; French: anguille d’Amerique; Italian: anguilla americana; Japanese: unagi; Portuguese: enguia-americana; Spanish: anguila, anguila americana; Swedish: amerikansk al.
Other names for European eel: silver eel, common eel, yellow eel, freshwater eel; Dutch: aal; Finnish: ankerias; French: anguille, anguille d’Europe; Italian: anguilla; Japanese: unagi; Portuguese: eiró, enguia; Russian: retschnoi ugor; Spanish: anguila, anguila europea; Swedish: al.
The American and European eels are member of the Anguillidae family of freshwater eels. They are common and have been the object of many wild tales speculating on the nature of their existence. Aristotle was convinced they rose spontaneously from mud, while Roman scholar Pliny the Elder believed young eels came from bits of skin that adult eels rubbed off on rocks. Italian fishermen believed that eels mated with water snakes. The most common hypothesis was that eels arose spontaneously from horse hairs that fell in the water. These many ancient theories likely occurred because of the mystery and complexity surrounding both fish; their spawning habits and many diverse growth changes are among the most unique of freshwater fishes.
These eels are preyed upon by many species at different stages of their existence. They are important forage for such larger offshore predators as sharks, haddock, and swordfish; for inshore species like striped bass; and for many species of birds, including bald eagles and various gulls. Their greatest predator, however, is likely man.
The American and European eel have been prized as food since ancient times and are caught in eel traps and nets, as well as by hook and line and spearing. They are intensively sought commercially in many places and considered a delicacy, especially in Europe and Japan. Eels of all sizes are desirable for consumption, although larger individuals, having spent many years on the bottom of lakes and rivers and being high in fat content, may be especially susceptible to elevated levels of contaminants in areas that are highly polluted.
Larger individuals (10 to 16 inches or so) are used as bait by anglers, especially those seeking big striped bass, and they may be sold as fish bait in coastal shops. Smaller individuals are also sold by commercial interests for consumption, and have been known to fetch many hundreds of dollars per pound. Increased coastal netting of small eels due to rising market demands has raised concerns about the exploitation of these fish. European and Asian stocks have been especially diminished, and North American stocks have likewise been under severe pressure. Elvers have been harvested for use in pond culture and aquaculture operations. They have also been caught and transplanted to inland waters to boost or establish eel stocks.
Identification. The body is elongate and snakelike with a pointed head and many teeth. It is covered with thick mucus, hence the term "slippery as an eel." The large mouth extends as far back as the midpoint of the eye or past it. There is a single gill opening just in front of the pectoral fins. There are no pelvic fins, and the soft-rayed dorsal, anal, and caudal fins form one continuous fin. There are no visible scales. Coloring changes with maturity, as described later in this text.
The American and European eels are almost identical; they can be distinguished only by counting vertebrae. The adult American eel has 103 to 111 vertebrae, whereas the European has 110 to 119.
Size/Age. American eels are able to reach 50 inches and 16 pounds. The average size for adult females is about 3 feet while adult males are considerably smaller, rarely growing more than a foot long. They can live longer than 9 years in rivers, streams, and lakes. European can achieve similar size and age, but are usually found smaller on average.
Distribution. The American eel occurs from southwest Greenland to Labrador, south along the North American coast to Bermuda, the Gulf of Mexico, Panama, and the Carribean islands. Withing this region inland it occurs from the Mississippi River drainage east, and northeast to the Great Lakes and to the Atlantic Ocean.
The European eel occurs in drainages feeding the North Atlantic, Baltic, and Mediterranean Seas, and along the east coast of Europe from the Black Sea to the White Sea. It has been introduced to Asia and South and Central America, but has not reproduced.
Habitat. These eels are catadromous, spending the majority of their life in freshwater and returning to saltwater to spawn. They prefer to dwell in heavy vegetation or burrow in the sandy bottom. Their physical structure is such that they can easily swim backward and dig tail first into soft bottom sediments.
Life History/Behavior. When it comes time to spawn, the males and females stop feeding, change in color from olive to black, and move out to sea. Both the American eel and European eel spawn in the same area of the Atlantic Ocean, in deep water at the north edge of the Sargasso Sea. There each female lays as many as 10 to 20 million eggs, and both sexes die after spawning.
The eggs float to the surface and soon hatch into slim, transparent larvae (glass eels). The sex an eel becomes is thought to be partly determined by environmental conditions such as crowding and food abundance, but is not determined until they are about 8 to 10 inches long in their freshwater habitat.
The larvae drift and swim for one year (American) or three years (European) with ocean currents toward river mouths. Males stay near the mouths of rivers while females travel upstream, mostly at night. Eels can absorb oxygen through their skin as well as gills, and are known to travel over land, particularly in damp, rainy weather. Balls of intertwined eels have been seen rolling up beaches in search of freshwater for overwintering.
Distinctive terms are used to identify these eels in size, coloring, and behavior at different stages of their lives. They are as follows:
Glass eels are those in the young larval stage called leptocephalus; they are shaped like willow leaves and have ribbon-like transparent bodies with a distinct black eye. These range from approximately 1 to 2.5 inches in length, and are attracted to coastal estuaries and freshwater, where they are the target of intense commercial fishing interest.
Elvers are small eels in the stage of adapting to freshwater. They range from 2.5 to 3.5 inches in length, and are darker in color than glass eels, being fully pigmented and ranging from gray to greenish brown. Mass upstream migrations of elvers have been observed. Though inconspicuous as they swim along river bottoms, they are very visible when they encounter obstructions like dams and waterfalls.
Yellow eels are growing eels that exist in freshwater. Some biologists refer to them as adults while others refer to them as subadults. In any event, they are sexually immature, and yellowish to olive-brown on the back and lighter on the belly. They swim freely along river bottoms, through shoreline rock crevices, and into silty lake bottoms in search of prey.
Silver eels are sexually mature adults that are dark with a bronze-black hue on the back and silver on the underside. Many have enlarged eyes, which is believed to give them better vision in the ocean. These are fish that are ready to migrate, or in the process of migrating, out of freshwater to their ocean spawning grounds, a process that is believed to take three to five months through the fall and winter.
Food. The diet of the nocturnal feeding American and European eels includes insect larvae, small fish, crabs, worms, clams, and frogs. They also feed on dead animals or on the eggs of fish, and are able to tear smaller pieces of food that are too large to be swallowed whole.
The feeding process on food that is large is rather unusual. These eels have relatively weak jaws that are mainly suited to grasping, yet they possess many small, round, and rather blunt teeth Because they are palindromic, meaning that they can move equally well forward or backward forcefully, they are able to pull, twist, and spin when tearing apart prey that is too large to be consumed whole. The habit of spinning, which also occurs when they are caught by anglers (with some consternation about line twist and grasping), deserves explanation.
Spinning Habits. When food cannot be consumed whole, or when it cannot be broken into swallow-size morsels by jerking and pulling, an eel spins at a dizzying rate. Researchers have recorded a rate of six to fourteen spins per second (Olympic ice skaters can spin five times per second). The purpose of this is to break apart food into sizes that can be consumed; that size is determined by the width of its mouth, which is said to seldom exceed 2 inches. It also serves the purpose of gaining access to interior portions of food items, such as entering the body cavity of a dead fish to consume its eggs.
The habit of spinning, however, is also one that brings attention to the eel itself. Eels may spin several times in a row for a protracted period, during which they are less alert to predators and more vulnerable. This tendency may in part account for some of the effectiveness of wavy and spinning lures and bait rigs in sportfishing applications.
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