Atlantic sturgeon
| Atlantic sturgeon | |
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| Species: | A. oxyrhynchus (originally A. sturio)
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| Subspecies: | A. o. oxyrhynchus
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| Trinomial name | |
| Acipenser oxyrhynchus oxyrhynchus Mitchell, 1815
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The Atlantic sturgeon (Acipenser sturio) is a member of the Acipenseridae family and is among one of the oldest fish species in the world. Its range extends from New Brunswick, Canada to the eastern coast of Florida. It was in great abundance when the first settlers came to America, but has since declined due to overfishing and water pollution. It is considered threatened, endangered and even extinct in much of its original habitats. The fish can reach sixty years of age, fifteen feet in length and over eight hundred pounds in weight.
Physical appearance
Rather than having true scales, the Atlantic sturgeon has five rows of bony plates known as scutes. Specimens weighing over eight hundred pounds and nearly fifteen feet in length have been recorded, but they typically grow to be six to eight feet and no more than three hundred pounds. Its coloration ranges from bluish-black and olive green on its back to white on its underside. It has a longer snout than other sturgeons and has four barbels at the side of its mouth.
Life cycle
Atlantic sturgeon under six years of age stay in the brackish water where they were born before moving into the ocean. They may be 3 to 5 feet long at this stage. In areas where the Shortnose sturgeon are also present, the adults of that species can be, and historically were for centuries, confused with immature Atlantic sturgeon. Atlantic sturgeon may take anywhere from seven to twenty-three years to become sexually mature, depending on the sex and temperature of the water. When mature, they travel upstream to spawn. The females may lay 800,000 to 3.75 million eggs in a single year, doing so every two to six years. After laying their eggs females will travel back downstream, but males may remain upstream after spawning until forced to return downstream by the increasingly cold water. They may even return to the ocean, where they stay near the coastline. Sturgeon can often live to the age of sixty years old. Accounts of sturgeon over the age of one hundred were not uncommon in colonial times. The species is also known for its occasional 'leaping' behavior, during which the fish will emerge completely out of the water in a forceful motion that can be hazardous to anything unlucky enough to be struck. The exact reason why sturgeon leap remains unknown.[2]
Economic history
Originally, the Atlantic sturgeon was considered a worthless fish. Its rough skin would often rip nets, keeping fishermen from catching more profitable fish. However, when products derived from the atlantic sturgeon were found, their popularity quickly rose.[citation needed] Sturgeon were one of the types of fish harvested at the first North American commercial fishery, and were the first cash "crop" harvested in Jamestown, Virginia. The colonies found atlantic sturgeon to be a profitable resource, second in profit only to lobsters [citation needed]. Other fisheries along the Atlantic coast harvested them for use as food, a leather material used in clothing and bookbinding, and isinglass, a gelatinous substance used in clarifying jellies, glues, wines and beer. In the late 19th century, seven million pounds of sturgeon meat was exported from the US per year. Within years, however, that amount dropped to 22,000 pounds. The number later rose to about 200,000 pounds a year in the 1950s. Now, sturgeons are primarily used for the production of caviar.
Conservation status
The U.S. government does not list the species as threatened or endangered on a nationwide level under the Endangered Species Act (ESA). However, the Atlantic sturgeon is a U.S. National Marine Fisheries Service Species of Concern. Species of Concern are those species about which the U.S. Government’s National Oceanic and Atmospheric Administration, National Marine Fisheries Service, has some concerns regarding status and threats, but for which insufficient information is available to indicate a need to list the species under the ESA. However, a new status review under the ESA has been conducted and Atlantic sturgeon are now considered candidate species.
The American Fisheries Society, however, considers the fish as threatened throughout its entire range, although it is believed to no longer inhabit the full range it once did. In the Chesapeake watershed, the James River in Virginia is one of the last confirmed holdouts for that region's nearly extirpated population. In May 2007 a survey identified 175 sturgeon remaining in the entire river, with 15 specimens exceeding five feet.[3] A bounty-based survey of live Atlantic sturgeon in Maryland's portion of the Bay found "a high number of captures reported in 2005-06.[4] http://www.dnr.state.md.us/fisheries/commercial/sturg100.htm The University of Georgia is also conducting an ongoing study on the life history of Atlantic sturgeon on the Altamaha river in Georgia.
Baltic population
Recent studies have shown that the now extinct sturgeon population in the Baltic Sea belonged to the atlantic stugeon subspecies rather than to the European variant (A. sturio) as previously thought. The research indicates that this species migrated to the Baltic about 1300 years ago and subsequently displaced the native species.[5]
Because of overfishing and pollution, however, the atlantic stugeon was extirpated from the Baltic sea in the beginning of the 20th century. A German-Polish project is now (2009) underway to re-introduce the sturgeon into the Baltic by releasing specimens caught in the Canadian Saint John river into the Oder, a river at the border between Germany and Poland where the species once spawned.[6]
Conservation designation
IUCN: Critically Endangered [7]
CITES: Appendix II
American Fisheries Society: Endangered in all stream systems except Conservation Dependent in Hudson, Delaware, and Altamaha river.
Management
Due to a long history of overfishing, Atlantic sturgeon are now a threatened species. Management of the species is largely based on the restriction of fishing of the species. This helps limit fishing mortalities of sturgeon to bycatch.
Current sturgeon population rebuilding plans are in place as goals and guidelines, but the growth of sturgeon population to a sustainable amount will be a long time coming.
See also
- Sturgeon
- Gulf sturgeon, Acipenser oxyrinchus desotoi, the other subspecies
References
- ^ Template:IUCN2008
- ^ Maryland DNR Fisheries Service - Fish Facts Web Site
- ^ [Karl Blankenship, Alliance for the Chesapeake Bay, "Bay Journal", Sept. 2007, p. 7 http://www.bayjournal.com/article.cfm?article=3152]
- ^ "Maryland Department of Natural Resources (2007?). Reward for Live Sturgeon. Accessed 8 August 2008.
- ^ http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=2527320
- ^ http://www.spiegel.de/international/0,1518,445158,00.html
- ^ [1]
5. New York State Department of Environmental Conservation - New York's Sturgeon [2]
http://dep.state.ct.us/burnatr/wildlife/factshts/atsturg.htm
http://www.maine.gov/dmr/recreational/fishes/sturgeon.htm Froese, Rainer, and Daniel Pauly, eds. (2008). "Acipenser oxyrinchus oxyrinchus" in FishBase. October 2008 version.
Burroughs, Frank [August 2006]. Confluence: Merrymeeting Bay. Gardiner, Maine: Tilbury House, 21-28. ISBN 978-0-88448-282-6.