Practical information to identify and manage non-native, invasive plants and animals
The Quiet Invasion:A Guide to Invasive Species of the Galveston Bay Area
Anguilla sp.
| ITIS TSN: | 161126 |
| Presence: | Species of Concern |
| Habitat: | Aquatic |
| Native Range: | Europe and Asia |
Human Health
This species is served as "unagi", a popular sushi dish. The blood of the European eels is poisonous, but the poison is destroyed by cooking (Coad 1995; Nico and Fuller 2010a).Prohibited Lists
This species is legally classified in Texas as exotic, harmful, or potentially harmful. No person may import, possess, sell, or place this species into state waters except as authorized by a rule or permit issued by the Texas Parks and Wildlife Department (TPWD). A person may possess exotic harmful or potentially harmful fish (exclusive of grass carp) without a permit only if the fish have been gutted.Introduction Pathways
Freshwater eels are imported by restaurants, fish farms, and live seafood markets from which they may escape or be released into local waters.Geographic Distribution
As of 2010, nonnative species of Anguilla are not reported in Texas. Nonnative Anguilla spp. have been reported in California, Nevada, Oregon, and Hawaii. Eels are extremely mobile and have even been known to move over land.Specific Primary Habitats
All freshwater eels have a catadromous life cycle. They spend the greater part of their life in freshwater rivers and streams or in brackish, shallow coastal waters and return to the ocean to spawn.Ecological, Economic, or Social Impact
Nonnative freshwater eels are known to feed on numerous species of fish and invertebrates and compete with native species of fish and invertebrates for prey. In Texas and South Carolina, the native American eel (Anguilla rostrata), has been infected by the Asian eel nematode (Anguicolla crassus). The nematode infects the swim bladder and may cause death to the animal (Nico and Fuller 2010a).Physical Description
Freshwater eels have long, snake-shaped bodies and a pointed snout. Dorsal fins are usually continuous with their caudal (tail) fins and anal fins. They have small pectoral fins and no pelvic fins. Scales are thin and soft. Freshwater eels can measure to 1.5 meters in length.Reproduction Characteristics
Adult eels spawn in the open ocean. Leaf-shaped larvae drift toward coastal waters. Just before entering coastal embayments, the larvae metamorphose into "glass eels". The glass eels move upstream into freshwater rivers and streams where they gain pigmentation and become known as "yellow eels". It is here that they spend the majority of their life. Adult eels migrate back to the ocean (as "silver eels") where they spawn and die. Freshwater eels may survive for 10 to 20 years and one female may produce up to 3 million eggs per 1 kilogram body weight (Nico and Fuller 2010a).Feeding
Eels are mostly nocturnal (they feed at night). The diet is broad and consists of marine, estuarine, and freshwater species. Juveniles may feed on insect larvae, molluscs, worms, and crustaceans. Adults feed on other species of fish (Nico and Fuller 2010a).Control
Since early detection is key to preventing the spread and establishment of this species, regional/local monitoring or surveillance is essential. Nonnative species of eels should not be imported or released in local waterways. If found in local waters, note the capture location, kill and freeze the fish, and notify the Texas Parks and Wildlife Department.Lists
This species belongs to the following lists:
Images
To view a larger version of an image, click on the thumbnail. The European eel (A. anguilla). Photo courtesy of Steffen Zienert, USGS NAS Database, http://nas.er.usgs.gov. |