Eel life history
Encyclopedia
Eel
Eels are an order of fish, which consists of four suborders, 20 families, 111 genera and approximately 800 species. Most eels are predators...
is a long, thin bony fish of the order Anguilliformes. Because fishermen never caught anything they recognized as young eels, the life cycle of the 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...
was a mystery for a very long period of scientific history. Although there have been more than 6500 publications about eels, much of its life history remains an enigma.
The European eel
European eel
The European eel, Anguilla anguilla, is a species of eel, a snake-like, catadromous fish. They can reach in exceptional cases a length of 1½ m, but are normally much smaller, about 60–80 cm, and rarely more than 1 m....
(Anguilla anguilla) was the one most familiar to Western scientists, beginning with Aristotle
Aristotle
Aristotle was a Greek philosopher and polymath, a student of Plato and teacher of Alexander the Great. His writings cover many subjects, including physics, metaphysics, poetry, theater, music, logic, rhetoric, linguistics, politics, government, ethics, biology, and zoology...
who did the first known research on eels. He stated that they are born of "earth worms", which emerged from the mud with no fertilization needed — they grew from the "guts of wet soil". For a long time, nobody could prove Aristotle wrong. Later scientists believed that the eelpout
Eelpout
The eelpouts are the ray-finned fish family Zoarcidae. As the common name suggests, they are somewhat eel-like in appearance, with elongate bodies, and the dorsal and anal fins continuous with the caudal fin. All of the approximately 220 species are marine, mostly bottom-dwelling, some at great...
Zoarces viviparus was the "Mother of Eels" (the translation of the German name "Aalmutter").
In 1777, the Italian Carlo Mondini found the creature's gonads and proved that eels are fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
. In 1876, the young Austrian student Sigmund Freud
Sigmund Freud
Sigmund Freud , born Sigismund Schlomo Freud , was an Austrian neurologist who founded the discipline of psychoanalysis...
dissected hundreds of eels in search of the male sex organs. He had to concede failure in his first published research paper, and turned to other issues in frustration.
Until 1893, larval eels — transparent, leaflike two-inch (five cm) creatures of the open ocean — were considered a separate species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
, Leptocephalus brevirostris (from the Greek
Greek language
Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...
leptocephalus meaning "thin- or flat-head"). In 1886, French zoologist Yves Delage kept leptocephali alive in a laboratory tank in Roscoff
Roscoff
Roscoff is a commune in the Finistère department of Brittany in northwestern France.The nearby Île de Batz, called Enez Vaz in Breton, is a small island that can be reached by launch from the harbour....
until they matured into eels, and in 1896 Italian
Italy
Italy , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...
zoologist Giovanni Battista Grassi
Giovanni Battista Grassi
Giovanni Battista Grassi was an Italian zoologist, known for work demonstrating that mosquitos carry the malaria parasite Plasmodium in their digestive tract, on the embryological development of honey bees, on parasites, particularly the vine parasite phylloxera, migrations and metamorphosis in...
observed the transformation of a Leptocephalus
Leptocephalus
A leptocephalus is the flat and transparent larva of the eel, marine eels, and other members of the Superorder Elopomorpha. Fishes with a leptocephalus larva stage include the most familiar eels such as the conger, moray eel, and garden eel, and the freshwater eels of the family Anguillidae, plus...
into a round glass eel in the Mediterranean Sea
Mediterranean Sea
The Mediterranean Sea is a sea connected to the Atlantic Ocean surrounded by the Mediterranean region and almost completely enclosed by land: on the north by Anatolia and Europe, on the south by North Africa, and on the east by the Levant...
, and recognized the importance of salt water to the process. Despite this discovery, the name leptocephalus is still used for larval eel.
Search for the spawning grounds
Denmark
Denmark is a Scandinavian country in Northern Europe. The countries of Denmark and Greenland, as well as the Faroe Islands, constitute the Kingdom of Denmark . It is the southernmost of the Nordic countries, southwest of Sweden and south of Norway, and bordered to the south by Germany. Denmark...
professor Johannes Schmidt
Johannes Schmidt (biologist)
Johannes Schmidt was a Danish biologist credited with discovering in 1920 that eels migrate to the Sargasso Sea to spawn...
, from 1904 onwards, directed many expeditions in the Mediterranean Sea and the North Atlantic, largely financed by the Carlsberg Foundation. He postulated from the similarity of all leptocephali he found that they all must originate from the same parent species. The further into the Atlantic Ocean
Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...
he propelled research ships, the smaller the leptocephali he caught. Finally, in 1922, he ended up south of Bermuda
Bermuda
Bermuda is a British overseas territory in the North Atlantic Ocean. Located off the east coast of the United States, its nearest landmass is Cape Hatteras, North Carolina, about to the west-northwest. It is about south of Halifax, Nova Scotia, Canada, and northeast of Miami, Florida...
in the Sargasso Sea
Sargasso Sea
The Sargasso Sea is a region in the middle of the North Atlantic Ocean, surrounded by ocean currents. It is bounded on the west by the Gulf Stream; on the north, by the North Atlantic Current; on the east, by the Canary Current; and on the south, by the North Atlantic Equatorial Current. This...
where he succeeded in catching the smallest eel-larvae ever seen.
However, Schmidt was unable to observe the spawning directly, nor did he find ready-to-spawn adults. From the size distribution of the leptocephali he collected, Schmidt formulated this part of the life history of the eel:
The larvae of European eels travel with the Gulf Stream
Gulf Stream
The Gulf Stream, together with its northern extension towards Europe, the North Atlantic Drift, is a powerful, warm, and swift Atlantic ocean current that originates at the tip of Florida, and follows the eastern coastlines of the United States and Newfoundland before crossing the Atlantic Ocean...
across the ocean and, after one to three years, their leptocephali reach a size of 75 – 90 mm before they reach the coasts of Europe. The common name for this recruiment stage of eels is glass eel, based on the transparency of the body. One famous place for large-scale collection of glass eels (for deli-food and stocking) is Epney at the Severn
River Severn
The River Severn is the longest river in Great Britain, at about , but the second longest on the British Isles, behind the River Shannon. It rises at an altitude of on Plynlimon, Ceredigion near Llanidloes, Powys, in the Cambrian Mountains of mid Wales...
in England. Glass eels are also eaten as food in Spain. Once they recruit to coastal areas they migrate up rivers and streams, overcoming all sorts of natural challenges — sometimes by piling up their bodies by the tens of thousands to climb over obstacles — and they reach even the smallest of creeks.
They can move themselves over wet grass and dig through wet sand to reach upstream headwaters and ponds, thus colonising the continent. In freshwater they develop pigmentation, turn into elvers (young eels) and feed on creatures like small crustacean
Crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...
s, worm
Worm
The term worm refers to an obsolete taxon used by Carolus Linnaeus and Jean-Baptiste Lamarck for all non-arthropod invertebrate animals, and stems from the Old English word wyrm. Currently it is used to describe many different distantly-related animals that typically have a long cylindrical...
s and insect
Insect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...
s. They grow up in 10 or 14 years to a length of 60 to 80 cm. In this stage they are now called yellow eels because of their golden pigmentation.
In July some individuals mature and then they migrate back towards the sea, crossing even wet grasslands at night to reach rivers that lead to the sea. Eel migration out of their freshwater growth habitats from various parts of Europe, or through the Baltic Sea
Baltic Sea
The Baltic Sea is a brackish mediterranean sea located in Northern Europe, from 53°N to 66°N latitude and from 20°E to 26°E longitude. It is bounded by the Scandinavian Peninsula, the mainland of Europe, and the Danish islands. It drains into the Kattegat by way of the Øresund, the Great Belt and...
in the Danish belts have been the basis of traditional fisheries with characteristic trapnets.
How the adults make the 6000 km (3,728.2 mi) open ocean journey back to their spawning grounds north of the Antilles
Antilles
The Antilles islands form the greater part of the West Indies in the Caribbean Sea. The Antilles are divided into two major groups: the "Greater Antilles" to the north and west, including the larger islands of Cuba, Jamaica, Hispaniola , and Puerto Rico; and the smaller "Lesser Antilles" on the...
, Haiti
Haiti
Haiti , officially the Republic of Haiti , is a Caribbean country. It occupies the western, smaller portion of the island of Hispaniola, in the Greater Antillean archipelago, which it shares with the Dominican Republic. Ayiti was the indigenous Taíno or Amerindian name for the island...
, and Puerto Rico
Puerto Rico
Puerto Rico , officially the Commonwealth of Puerto Rico , is an unincorporated territory of the United States, located in the northeastern Caribbean, east of the Dominican Republic and west of both the United States Virgin Islands and the British Virgin Islands.Puerto Rico comprises an...
remains unknown. By the time they leave the continent their gut dissolves making feeding impossible, so they have to rely on stored energy alone. The external features undergo other dramatic changes as well: the eye
Eye
Eyes are organs that detect light and convert it into electro-chemical impulses in neurons. The simplest photoreceptors in conscious vision connect light to movement...
s start to enlarge in size, the eye pigments change for optimal vision in dim blue clear ocean light, and the sides of their bodies turn silvery, to create a countershading pattern to make them difficult to see by predators during their long open ocean migration. These migrating eels are typically called "Silver Eels" or "Big Eyes".
The German fisheries biologist Friedrich Wilhelm Tesch, an eel expert and author of the book "The Eel" (ISBN 0-632-06389-0), conducted many expeditions with high-tech instrumentation to follow eel migration, first down the Baltic, then along the coasts of Norway
Norway
Norway , officially the Kingdom of Norway, is a Nordic unitary constitutional monarchy whose territory comprises the western portion of the Scandinavian Peninsula, Jan Mayen, and the Arctic archipelago of Svalbard and Bouvet Island. Norway has a total area of and a population of about 4.9 million...
and England, but finally the transmitter signals were lost at the continental shelf
Continental shelf
The continental shelf is the extended perimeter of each continent and associated coastal plain. Much of the shelf was exposed during glacial periods, but is now submerged under relatively shallow seas and gulfs, and was similarly submerged during other interglacial periods. The continental margin,...
when the batteries ran out. According to Schmidt a travel speed in the ocean of 15 km per day can be assumed, so a silver eel would need 140 to 150 days to reach the Sargasso Sea from around Scotland and in about 165 to 175 when leaving from the English Channel.
Tesch — like Schmidt — kept on trying to persuade sponsors to give more funding for expeditions. His proposal was to release fifty Silver Eels from Danish waters with transmitters that will detach from the eels each second day, float up and broadcast position, depth and temperature to satellite receivers, possibly jointly with an equivalent release experiment from the countries of the western coast of the Atlantic. However, only preliminary experiments such as these have so far been performed.
Today our sum of the only knowledge about the fate of individual silver eels once they leave the continental shelf is based on three eels found in the stomachs of deep sea fishes, that include whales caught off Ireland
Ireland
Ireland is an island to the northwest of continental Europe. It is the third-largest island in Europe and the twentieth-largest island on Earth...
and off the Azores
Azores
The Archipelago of the Azores is composed of nine volcanic islands situated in the middle of the North Atlantic Ocean, and is located about west from Lisbon and about east from the east coast of North America. The islands, and their economic exclusion zone, form the Autonomous Region of the...
and some experiments on the physiology of eels in the laboratory.
There is another Atlantic Eel species: the American eel
American eel
The American eel, Anguilla rostrata, is a catadromous fish found on the eastern coast of North America. It has a snake-like body with a small sharp pointed head. It is brown on top and a tan-yellow color on the bottom. It has sharp pointed teeth but no pelvic fins...
, Anguilla rostrata. First it was believed European and American eels were the same species due to their similar appearance and behavior, but research has shown that they differ in chromosome count and various molecular genetic markers, and in the number of vertebrae, Anguilla anguilla counting 110 to 119 and Anguilla rostrata 103 to 110.
The spawning grounds for the two species are in an overlapping area of the southern Sargasso Sea, with A. rostrata apparently being more westward than A. anguilla, and with some spawning by the American eel possibly even occurring off the Yucatan Peninsuala outside of the Gulf of Mexico
Gulf of Mexico
The Gulf of Mexico is a partially landlocked ocean basin largely surrounded by the North American continent and the island of Cuba. It is bounded on the northeast, north and northwest by the Gulf Coast of the United States, on the southwest and south by Mexico, and on the southeast by Cuba. In...
, but this has not been confirmed. After spawning in the Sargasso Sea and moving to the west, the leptocephali of the American eel exit the Gulf Stream earlier than the European eel and begin migrating into the estuaries along the east coast of North America between February and late April at an age of about one year and a length of about 60 mm.
The spawning area of the Japanese eel
Japanese eel
The Japanese eel, Anguilla japonica, is a species of eel found in Japan, Korea, Vietnam the East China Sea and the northern Philippines. Like the all the eels of its family, it is catadromous, meaning it lives parts of its life in both freshwater and saltwater. The specific spawning grounds have...
, Anguilla japonica, has also been precisely located to be to the west of the Suruga seamount and their leptocephali are then transported to the west to East Asia by the North Equatorial Current.
Furthermore, in June and August 2008, Japanese scientists discovered and caught matured adult eels of A. japonica and A. marmorata in the West Mariana Ridge.
Decline of the glasseels
Maine
Maine is a state in the New England region of the northeastern United States, bordered by the Atlantic Ocean to the east and south, New Hampshire to the west, and the Canadian provinces of Quebec to the northwest and New Brunswick to the northeast. Maine is both the northernmost and easternmost...
and other North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
n coasts showed similar declines, although not as drastic.
In 1997 Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
an demand for eels could not be met for the first time ever, and dealers from Asia bought all they could. The traditional European stocking programs could not compete any longer: each week the price for a kilogram of glasseel went up another US$30. Even before the 1997 generation hit the coasts of Europe, dealers from China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
alone placed advance orders for more than 250,000 kg, some bidding more than $1,100 per kg. Asian elvers have sold in Hong Kong for as much as $5,000 to $6,000 a kilogram at times when $1,000 would buy the same amount of American glasseels with gunfights at their catching sites. Such a kilogram, consisting of 5000 glasseels, may bring at least $60,000 and as much as $150,000 after they leave an Asian fish farm. In New Jersey over 2000 licences for glasseel catch were issued and reports of 38 kg per night and fisherman have been made, although the average catch is closer to 1 kg.
The demand for adult eels has continued to grow, . Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
imported more than $50 million worth of eels in 2002. In Europe 25 million kg are consumed each year, but in Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
alone more than 100 million kg were consumed in 1996. As the European eels become less available, worldwide interest in American eels has increased dramatically.
New high-tech eel aquaculture plants are appearing in Asia
Asia
Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...
with detrimental effects on the native Japanese eel, Anguilla japonica. Traditional eel aquaculture operations rely on wild-caught elvers, but experimental hormone treatments in Japan have led to artificially spawned eels. Eggs from these treated eels have a diameter of about 1 mm, and each female can produce 2 to 10 million eggs.
Threats to eels
There are strong concerns that the European eel population might be devastated by a new threat: Anguillicola crassusAnguillicola crassus
Anguillicoloides crassus is a parasitic nematode worm that lives in the swimbladders of eels and appears to spread easily among eel populations after introduction to a body of water. It is considered to be one of the threats to the sustainability of populations of European eel...
, a foreign parasitic nematode
Nematode
The nematodes or roundworms are the most diverse phylum of pseudocoelomates, and one of the most diverse of all animals. Nematode species are very difficult to distinguish; over 28,000 have been described, of which over 16,000 are parasitic. It has been estimated that the total number of nematode...
. This parasite from East Asia (the original host is Anguilla japonica) appeared in European eel populations in the early 1980s. Since 1995 it also appeared in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
(Texas
Texas
Texas is the second largest U.S. state by both area and population, and the largest state by area in the contiguous United States.The name, based on the Caddo word "Tejas" meaning "friends" or "allies", was applied by the Spanish to the Caddo themselves and to the region of their settlement in...
and South Carolina
South Carolina
South Carolina is a state in the Deep South of the United States that borders Georgia to the south, North Carolina to the north, and the Atlantic Ocean to the east. Originally part of the Province of Carolina, the Province of South Carolina was one of the 13 colonies that declared independence...
), most likely due to uncontrolled aquaculture eel shipments. In Europe, eel populations are already from 30% to 100% infected with the nematode. Recently it was shown that this parasite inhibits the function of the swimbladder as a hydrostatic organ (Wuertz et al. 1996). As an open ocean voyager, eels need the carrying capacity of the swimbladder (which makes up 3–6% of the eel's bodyweight) to cross the ocean on stored energy alone.
Because the 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 in the sea), dams and other river obstructions can block their ability to reach inland feeding grounds. Since the 1970s an increasing number of eel ladder
Eel ladder
An eel ladder is type of fish ladder designed to help eels swim past barriers, such as dams and weirs or even natural barriers, to reach upriver feeding grounds...
s have been constructed in North America and Europe to help the fish bypass obstructions.
In New Jersey
New Jersey
New Jersey is a state in the Northeastern and Middle Atlantic regions of the United States. , its population was 8,791,894. It is bordered on the north and east by the state of New York, on the southeast and south by the Atlantic Ocean, on the west by Pennsylvania and on the southwest by Delaware...
, an ongoing project monitors the glasseel migration with an online in situ microscope. As soon as more funding becomes available, it will be possible to log into the system via a Longterm Ecological Observatory (LEO) site.
Further reading
- Tesch, F-W (2003) The eel. Blackwell Science, Oxford (UK). 1 - 408pp.
- Wallace, Karen (1993) Think of an Eel, Walker Books (UK) - Children's picture book describing the life cycle of the eel.
- Wenner, C.A. (1978). Anguillidae. In W. Fischer (ed.) FAO species identification sheets for fishery purposes. West Atlantic (Fishing Area 31). volume 1. [pag. var.]. FAO, Rome.
- Smith, C.L. (1997). National Audubon Society field guide to tropical marine fishes of the Caribbean, the Gulf of Mexico, Florida, the Bahamas, and Bermuda. Alfred A. Knopf, Inc., New York. 720 p.
- Robins, Richard C., Reeve M. Bailey, Carl E. Bond, James R. Brooker, Ernest A. Lachner, et al. 1980. A List of Common and Scientific Names of Fishes from the United States and Canada, Fourth Edition. American Fisheries Society Special Publication, no. 12. American Fisheries Society. Bethesda, Maryland, USA. 174.
- Robins, Richard C., Reeve M. Bailey, Carl E. Bond, James R. Brooker, Ernest A. Lachner, et al. 1980. A List of Common and Scientific Names of Fishes from the United States and Canada, Fourth Edition. American Fisheries Society Special Publication, no. 12. American Fisheries Society. Bethesda, Maryland, USA. 174.
- Robins, C.R. and G.C. Ray (1986). A field guide to Atlantic coast fishes of North America. Houghton Mifflin Company, Boston, U.S.A. 354 p.
- Piper, R (2007), Extraordinary Animals: An Encyclopedia of Curious and Unusual Animals, Greenwood Press.
- Page, L.M. and B.M. Burr (1991). A field guide to freshwater fishes of North America north of Mexico. Houghton Mifflin Company, Boston. 432 p.
- Ogden, J.C., J.A. Yntema, and I. Clavijo (1975). An annotated list of the fishes of St. Croix, U.S. Virgin Islands. Spec. Publ. No. 3.
- Nigrelli, R.F. (1959). Longevity of fishes in captivity, with special reference to those kept in the New York Aquarium. p. 212-230. In G.E.W. Wolstehnolmen and M. O'Connor (eds.) Ciba Foundation Colloquium on Ageing: the life span of animals. Vol. 5., Churchill, London.
- Nielsen, J.G. and E. Bertelsen (1992). Fisk i grønlandske farvande. Atuakkiorfik, Nuuk. 65 s.
- Nelson, Joseph S., Edwin J. Crossman, Héctor Espinosa-Pérez, Lloyd T. Findley, Carter R. Gilbert, Robert N. Lea, and James D. Williams, eds. 2004. Common and scientific names of fishes from the United States, Canada, and Mexico, Sixth Edition. American Fisheries Society Special Publication, no. 29. American Fisheries Society. Bethesda, Maryland, USA. ix + 386. ISBN 1-888569-61-1.
- Murdy, Edward O., Ray S. Birdsong, and John A. Musick 1997. Fishes of Chesapeake Bay. Smithsonian Institution Press. Washington, DC, USA. xi + 324. ISBN 1-56098-638-7.
- Lim, P., Meunier, F.J., Keith, P. and Noël, P.Y. (2002). Atlas des poissons et des crustacés d'eau douce de la Martinique. Patrimoines Naturels, 51: 120p. Paris: MNHN.
- Kenny, J.S. (1995). Views from the bridge: a memoir on the freshwater fishes of Trinidad. Julian S. Kenny, Maracas, St. Joseph, Trinidad and Tobago. 98 p.
- Jessop, B.M. (1987). Migrating American eels in Nova Scotia. Trans. Amer. Fish. Soc. 116:161-170.
- International Game Fish Association (1991). World record game fishes. International Game Fish Association, Florida, USA.
- Greenfield, D.W and J.E Thomerson (1997). Fishes of the continental waters of Belize. University Press of Florida, Florida. 311 p.
- Food and Agriculture Organization (1992). FAO yearbook 1990. Fishery statistics. Catches and landings. FAO Fish. Ser. (38). FAO Stat. Ser. 70:(105):647 p.
- Fish, M.P. and W.H. Mowbray (1970). Sounds of Western North Atlantic fishes. A reference file of biological underwater sounds. The Johns Hopkins Press, Baltimore.
- FAO (1997). Aquaculture production statistics 1986-1995. FAO Fish. Circ. 815, Rev. 9. 195 p.
- Eschmeyer, William N., ed. 1998. Catalog of Fishes. Special Publication of the Center for Biodiversity Research and Information, no. 1, vol 1-3. California Academy of Sciences. San Francisco, California, USA. 2905. ISBN 0-940228-47-5.
- Erdman, D.S. (1984). Exotic fishes in Puerto Rico. p. 162-176. In W.R. Courtney, Jr. and J.R. Stauffer, Jr. (eds.) Distribution, biology and management of exotic fishes. Johns Hopkins University Press, Baltimore, USA.
- Claro, Rodolfo, and Lynne R. Parenti / Claro, Rodolfo, Kenyon C. Lindeman, and L. R. Parenti, eds. 2001. Chapter 2: The Marine Ichthyofauna of Cuba. Ecology of the Marine Fishes of Cuba. Smithsonian Institution Press. Washington, DC, USA. 21-57. ISBN 1-56098-985-8.
- Claro, R. (1994). Characterísticas generales de la ictiofauna. p. 55-70. In R. Claro (ed.) Ecología de los peces marinos de Cuba. Instituto de Oceanología Academia de Ciencias de Cuba and Centro de Investigaciones de Quintana Roo.
- Böhlke, J.E. and C.C.G. Chaplin (1993). Fishes of the Bahamas and adjacent tropical waters. 2nd edition. University of Texas Press, Austin.
- Butsch, R.S. (1939). A list of Barbadian fishes. J. B.M.H.S. 7(1):17-31.
- Bussing, W.A. (1998). Peces de las aguas continentales de Costa Rica [Freshwater fishes of Costa Rica]. 2nd Ed. San José Costa Rica: Editorial de la Universidad de Costa Rica. 468 p.
- Banks, R. C., R. W. McDiarmid, A. L. Gardner, and W. C. Starnes 2003. Checklist of Vertebrates of the United States, the U.S. Territories, and Canada.