Friday, August 29, 2014

Bullseye Snakehead


Bullseye Snakehead (Channa marulius)

Introduction
The Bullseye Snakehead is an air breathing, invasive fish species that is rapidly spreading throughout Southern Florida. Introduced into Florida waters by careless disposal of aquarium pets or by illegal stocking sometime prior to 20001 , the Bullseye Snakehead is a top predator. The Peacock Bass (itself an invasive species) and Large Mouth Bass are top predators that compete for the same waters and food stock, and often prey on Bullseye Snakehead fry.

At the moment, the impact of Bullseye Snakehead in Southern Florida is difficult to measure. Anglers we interviewed suggest no significant drop off in Peacock Bass or Largemouth Bass fishing in waters invaded by Bullseye Snakehead. Studies of feeder species such as frogs, bluegill, warmouth, mosquito fish, lizards, turtles, toads, snakes and rats are ongoing.

Federal Regulation of the Bullseye Snakehead
However, the United States Fish and Wildlife Service determined that regulation of all snakehead species is necessary to protect native wildlife. On October 4, 2002, the entire snakehead family of fish (Channidae) including those currently recognized, and those that may be described in the future, was added to the injurious wildlife list described under the Lacey Act. Under this Act, it is illegal to import snakeheads into the United States or transport them across United States lines without permit. Permits for importation or interstate transportation can be obtained from the U.S. Fish and Wildlife Service Division of Management Authority (800-358-2104). Permits are issued for specific uses only, including medical or scientific research and education2. Anglers who catch Bullseye Snakehead are strongly encouraged to kill them immediately.
Two Department of the Interior (DOI) agencies are responsible for researching and regulating snakeheads. The first, a research branch of the DOI, is the United States Geological Survey (USGS; http://www.usgs.gov). USGS scientists conducted detailed, worldwide research on snakeheads that provided the basis for regulating snakehead importation and interstate transport. Research funding was sponsored by another DOI agency, the U.S. Fish and Wildlife Service (FWS; http://www.fws.gov). The U.S Fish and Wildlife Service is responsible for fisheries management, regulations, law enforcement, and education. The mission of the FWS is to work with others to conserve, protect, and enhance fish, wildlife, and plants for the continued benefit of the American people.3

Why are Bullseye Snakehead Banned?

According to the USGS studies, the Bullseye Snakehead pose a “significant threat to fish and wildlife resources of the United States”. The fear is that the Bullseye Snakehead will migrate to other waters absent of other top predators. In waterways where competition is scarce or non-existent, the voracious Bullseye Snakehead could destroy populations of other indigenous fish. Lakes and rivers in northern Florida, and the rest of the southern United States are vulnerable to Bullseye Snakehead predation. The USGS sites these reasons as well:
1. They are very predatory and could alter conditions in our aquatic ecosystems.
2. They are air breathers and several snakehead species, including the Bullseye Snakehead, are capable of overland migration during some part of their lives.
3. Some snakehead species have a very large potential range in the United States
4. They aggressively protect their young.4

Classification

Class Actinopterygii

   • Subclass Neopterygii

    • Order Perciformes

      • Suborder Channoidei

        • Family Channidae

          • Group Fishes

            • Genus Channa

              • Species Marulius

               • Common Name Bullseye Snakehead

bullseye snakehead image

Bullseye Snakehead Photo courtesy of Next World Exotics



Bullseye Snakehead – Alternative Names
The Bullseye Snakehead is indigenous to many places in Asia (genera = Channa). Given the many cultures and languages on these continents, it is not surprising that the Bullseye Snakehead has many names. Below is a list of the more common names.

1. “Pla chon ngu hao” meaning cobra (near Bankok, Thailand)
2. Ara (in Sri Lanka)
3. Bhor & Pumurl (in Bijar of India)
4. Bral, chaeru-veraal & Curuva (in Kerala of India)
5. Cobra snakehead
6. Gajal and Sal (In West Bengal state, India)
7. Gangara, Kalumaha and Ara (Sinhalese, Sri Lanka)
8. Giant snakehead
9. Great snakehead
10. Haal (in Assam of India)
11. Indian snakehead
12. Iru viral (Tamil, Sri Lanka)
13. Kubrah (in Punjab of India)
14. Madinji, hoovina-murl and Aviu (in Karnataka of India)
15. Phoola-chapa, Poomeenu & phool-mural (in Andra Pradesh of India)
16. Puveral & Aviri (In Tamil Nadu of India)
17. Saal (in Orissa, India)
18. Sawal, Kubrah and Dowlah (in Punjab state of India)
19. Soal (in Pakistan)
20. Trey Raws (in Cambodia)5

Bullseye Snakehead – Native Range
The Bullseye Snakehead prefers rivers with sandy or rocky substrate and deep lakes with clear water.6 It is native to these countries:

1. Sri Lanka
2. Bangladesh
3. Pakistan
4. Myanmar
5. India
6. Southern China
7. Southern Nepal
8. Thailand
9. Cambodia
10. Laos 7

Bullseye Snakehead Size
The Bullseye Snakehead a fast growing, carnivorous species, and is the largest in Channidae family. It can reach 120-122 cm in length and can weigh up to 30.0 kgs.8

Identification
The Bullseye Snakehead has an “eye-like” orange and black marking on its caudal peduncle. Would be predators often mistake this marking for the Bullseye Snakehead’s eye and steer away.
(The fish body becomes thinner and narrower toward the tail. This area is referred to as the caudal peduncle. Normally, the caudal peduncle is measured from the back of the anal fin to the beginning of the caudal (tail) fin.)

Bullseye snakehead picture

Bullseye Snakehead Photo courtesy of Next World Exotics

Mistaken Identity – Bowfin are often mistaken for Bullseye Snakehead

The Bullseye Snakehead is often mistaken for a bowfin. In the image below, the bowfin has yellow outlined – blackish “eyespot” on its caudal peduncle.

bowfin marking

Common Bowfin


comparison of bullseye snakehead and bowfin

Comparison of Snakehead to Bowfin. Diagrams courtesy of the USGS.


Bullseye Snakehead – Current Range United States Range

Bullseye Snakehead are prevalent in the canals and lakes of Broward and Lee Counties, Florida.

usgs map for bullseye snakehead area

Bullseye Snakehead Range courtesy of USGS

Walking Bullseye Snakehead
Hollywood hyperbole suggests snakehead have terrifying ability to traverse great distances over land. In reality, several species of snakehead, including the Bullseye Snakehead, are able to move from one body of water to another over land, especially if the ground is wet. Bullseye snakehead must remain most during their overland migrations. If exposed to dryness too long, the Bullseye Snakehead will die.
Movement across land is achieved by flexing their body and pushing with their tail, while using their broad pectoral fins to stabilize their head. It is unknown how far they can travel on land. This crawling ability is reduced in larger species of snakeheads as they reach adulthood.9

Impact of Introduction:

The Bullseye Snakehead has the potential to impact native fish and crustaceans through predation. Researchers examined the stomach contents of 127 dead Bullseye Snakeheads in Florida, they discovered that 13 were the snakehead own species plus one bluegill, seven warmouth, 11 mosquito fish, 2 peacock bass, several pieces of lizards, small turtles, bufo toads, a snake and a rat. It was also noted that no remains of largemouth bass were discovered (Cocking 2008).10

They are preyed upon by peacock bass and largemouth bass. Looking at 68 peacock bass’ stomachs, researchers found 16 snakeheads. In 41 largemouth bass, they found one (Cocking 2008).11 Other predators that consume Bullseye Snakehead fry include: gars, sunfish, perch, pike and wading birds.

Peacock Bass and Large Mouth Bass
The angler below displays a Peacock Bass. The Peacock Bass and Large Mouth Bass compete with Bullseye Snakehead for top spot on the food chain in southern Florida’s lakes and rivers.

Peacock Bass Photo courtesy of Next World Exotics

Reproduction

Bullseye Snakehead spawning typically occurs once to twice per year during warmer weather periods. Bullseye Snakehead build nests and lay pale red-yellow eggs. The eggs are approximately 2mm in diameter. Parental Bullseye Snakehead aggressively defend their nests, and guard the fry until they reach about 10 cm in length. Brood size varies significantly, ranging from 350 to over 3600 fry. 12

Commercial Importance
In its native range, the Bullseye Snakehead is popular as both a food and sport fish.
In the United States, there is little in the way of consumption. However, the Bullseye Snakehead is gaining popularity amongst sport fisherman due to the incredible fight it offers. Fishermen we interviewed in Southern Florida expressed strong preference for Bullseye Snakehead fishing when compared to fishing for Peacock and Large Mouth bass.

Nutritional Value
Bullseye Snakehead meat is very nutritious and is suggested to have wound healing effect and recuperative attributes.13

Catching a Bullseye Snakehead
The USGS provides these guidelines to anglers who catch Bullseye Snakehead:
1. Do not release the fish or throw it up on the bank (it could wiggle back into the water). Remember the Bullseye Snakehead is an air breather and can live out of water for a long time.
2. Kill the fish by freezing it or putting it on ice for an extended length of time.
3. Photograph the fish so that the species of snakehead fish can be positively identified.
4. Contact your nearest fish and game agency or the US Fish and Wildlife Service (703-358-2148) as soon as possible. Keeping data on the size, number and location of where snakeheads are caught or seen is vital to controlling this invasive fish.14

End Notes

1 http://fl.biology.usgs.gov/Snakehead_circ_1251/html/lit_and_bkgd_continued.html

2 http://fl.biology.usgs.gov/Snakehead_circ_1251/html/flyer.html

3http://fl.biology.usgs.gov/Snakehead_circ_1251/html/flyer.html

4 http://fl.biology.usgs.gov/Snakehead_circ_1251/html/flyer.html

5http://fl.biology.usgs.gov/Snakehead_circ_1251/circ_1251_courtenay_89-96.pdf

6 http://en.wikipedia.org/wiki/Channa_marulius

7 http://fl.biology.usgs.gov/Snakehead_circ_1251/html/channa_marulius.html

8 http://fl.biology.usgs.gov/Snakehead_circ_1251/html/channa_marulius.html

9http://fl.biology.usgs.gov/Snakehead_circ_1251/html/flyer.html

10http://nas.er.usgs.gov/queries/FactSheet.aspx?speciesID=2266

11http://nas.er.usgs.gov/queries/FactSheet.aspx?speciesID=2266

12 http://nas.er.usgs.gov/queries/FactSheet.aspx?speciesID=2266

13http://en.wikipedia.org/wiki/Channa_marulius

14http://fl.biology.usgs.gov/Snakehead_circ_1251/html/flyer.html

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