Atlantic sturgeon

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Atlantic sturgeon
Conservation status
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Acipenseriformes
Family: Acipenseridae
Genus: Acipenser
Species: A. oxyrhynchus
Subspecies: A. o. oxyrhynchus
Trinomial name
Acipenser oxyrhynchus oxyrhynchus
Mitchill, 1815

The Atlantic sturgeon (Acipenser oxyrinchus oxyrinchus) is a North American member of the Acipenseridae family and is among the oldest fish in the world. It is one of two subspecies of A. oxyrinchus, the other being the Gulf sturgeon, A. oxyrinchus desotoi. The range of the Atlantic sturgeon extends from New Brunswick, Canada to the eastern coast of Florida. It was in great abundance when the first settlers came to North 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 (4.6 m) in length and over eight hundred pounds (360 kg) in weight.[2]

Physical appearance[edit]

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 (1.8–2.4 m) and no more than three hundred pounds (140 kg). 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[edit]

Atlantic sturgeon under six years of age stay in the brackish water where they were born before moving into the ocean. They may be 3–5 feet (0.91–1.52 m) 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,[citation needed] 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.[citation needed] 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.[3]

Economic history[edit]

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. However, the primary reason for catching sturgeon was the high quality caviar that could be made cheaply from its eggs, called Black Gold by watermen. 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.

Conservation status[edit]

In February 2012, the Atlantic Sturgeon was officially classified as an endangered species by the National Oceanic and Atmospheric Administration Fisheries Service.[4]

The American Fisheries Society 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 population. In May 2007 a survey captured 175 sturgeon in the river, with 15 specimens exceeding 5 feet (1.5 m).[5] 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.[6][7] The University of Georgia is also conducting an ongoing study on the life history of Atlantic sturgeon on the Altamaha River in Georgia.[citation needed]

Baltic population[edit]

Recent studies have shown that the now nearly extinct sturgeon population in the Baltic Sea belonged to the Atlantic sturgeon 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.[8]

Because of overfishing and pollution, however, the Atlantic sturgeon was extirpated from most the Baltic sea in the beginning of the 20th century.[citation needed] 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.[9]

The last known specimen of the Atlantic sturgeon in the Baltic region was caught in 1996 near Muhumaa in Estonia. It was 2.9 meters long, weighed 136 kilograms, and was estimated to be approximately 50 years old.[10]

Conservation designation[edit]

IUCN: Near Threatened[1]

CITES: Appendix II

American Fisheries Society: Endangered in all stream systems except Conservation Dependent in Hudson, Delaware, and Altamaha river. However, on Jan. 31, 2012, the National Marine Fisheries Service (NMFS) announced that it will list the Atlantic sturgeon in the Delaware River as an endangered species under the federal Endangered Species Act, because the species is presently in danger of extinction. The Atlantic sturgeon of the Delaware River are listed as part of the New York Bight distinct population segment, which includes all Atlantic sturgeon that spawn in watersheds draining to coastal waters from Chatham, MA to the Delaware-Maryland border on Fenwick Island. NMFS believes there are fewer than 300 spawning adults in the Delaware River population; just over 100 years ago there were estimated to be 180,000 spawning adult females.

Management[edit]

Due to a long history of overfishing[citation needed], 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.[citation needed]

References[edit]

Citations
  1. ^ a b St. Pierre, R. (U.S. Fish & Wildlife Service) (2006). Acipenser oxyrinchus ssp. oxyrinchus. In: IUCN 2008. IUCN Red List of Threatened Species. Retrieved 23 February 2009.
  2. ^ Schultz, Ken (2004). Ken Schultz's Field Guide to Freshwater Fish. John Wiley & Sons. ISBN 978-0-471-62865-1. 
  3. ^ Maryland DNR Fisheries Service - Fish Facts Web Site
  4. ^ "Atlantic sturgeon listed as endangered species". Washington Post. Retrieved 8 February 2012. 
  5. ^ Karl Blankenship (Sep 2007). "Biologists fail to successfully spawn two female Atlantic sturgeon". Chesapeake Bay Journal. Retrieved 2012-03-30. 
  6. ^ "Maryland Department of Natural Resources (2007?). Reward for Live Sturgeon. Accessed 8 August 2008.
  7. ^ "Reward for Live Atlantic Sturgeon". Maryland Department of Natural Resources. Archived from the original on 2010-01-04. Retrieved 2012-02-03. 
  8. ^ http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=2527320
  9. ^ http://www.spiegel.de/international/0,1518,445158,00.html
  10. ^ "Muhu Maria jäi viimaseks Läänemerest püütud atlandi tuuraks". Saarlane.ee. (Estonian)
General references