Rainbow smelt

Rainbow smelt
Conservation status
Data Deficient (IUCN 2.3)
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Order:	Osmeriformes
Family:	Osmeridae
Genus:	Osmerus
Species:	O. mordax
Binomial name
Osmerus mordax (Mitchill, 1814)
Subspecies
Osmerus mordax mordax Osmerus mordax dentex

The rainbow smelt, Osmerus mordax, is an anadromous species of fish inhabiting rivers and coastal areas of North America.

Description

The body of the rainbow smelt is slender and cylindrical. It has a silvery, pale green back and is iridescent purple, blue, and pink on the sides, with a light underside. When full grown, the rainbow smelt is between 7 and 9 inches (18 and 23 cm) long and weighs about 3 ounces (85 g), and ones over 12 inches (30 cm) are known.

Distribution and habitat

The rainbow smelt's distribution extends from New Jersey to Labrador on the east coast and from Vancouver Island to the Arctic Ocean on the west coast. It has been introduced to the Great Lakes, and from there has made its way to various other inland bodies of water in Ontario and the midwestern United States. It occurs in rivers, coastal areas and ponds.

Ecology

They eat zooplankton, invertebrates and other fish, including small smelt, sculpins, burbot, and whitefish. They are preyed upon by larger predatory fish such as coho salmon, burbot, trout, walleye, and yellow perch.

In their anadromous territories, they spend the summers along the coast, normally in waters no more than 20 feet (6.1 m) deep and no more than 1 mile (1.6 km) from shore. They overwinter under the ice in estuaries, producing an antifreeze protein and glycerol.^[1] In the spring, they spawn at night in small streams, often ones that go dry in the summer. Landlocked populations were historically known in Maine, and it was from one of these that they were introduced to one of the lakes in Michigan known as Crystal Lake, and then spread to the Great Lakes.

Since being introduced to the Great Lakes, rainbow smelt have been considered an invasive species and though they provide food for many native species of larger game fish, they also prey upon the young of these and other fish. They have been found to impact populations of lake herring, yellow perch, whitefish, bloaters, alewives, slimy sculpin, walleye, and lake trout.

Fishing

Rainbow smelt are fished both commercially and for sport. Commercial harvests are down from historic levels; for example around 1850 an annual harvest from the Charles River alone was around 9 million fish. They are commonly processed into animal feed, but are also eaten by humans. They are a popular winter game fish and the spring smelt run is a tradition in many parts of their distribution.

Fishing for rainbow smelt using a gill net is a popular activity along the city of Chicago's lakefront. The season is open during the month of April. Superstition dictates that the fisherman must bite the head off the first fish of the season to have a good catch.

Conservation

Rainbow smelt are spring spawners and prefer clean streams with light flow and light siltation. They face several barriers to migration, being weak swimmers they cannot overcome most fish ladders. This prevents them from making it past the dams to the headwater streams where they need to spawn. The rise in erosion and dams help to decimate the smelt population in the 1980s. Right now there are plans to try to reduce damming and to help control erosion. With current efforts to reduce the human impact on these and many other affected species the population is back on the rise. Future management recommendations are to continue to protect these streams from erosion and also to find ways to make the streams that do have dams more accessible to smaller, weaker swimming fish. With these things happening the population will thrive. Eventually these fish may become over populated and small-scale removal may be necessary.

References

1. ^ Treberg, J. R.; Wilson, C. E.; Richards, R. C.; Ewart, K. V.; Driedzic, W. R. (2002). "The freeze-avoidance response of smelt Osmerus mordax: initiation and subsequent suppression of glycerol, trimethylamine oxide and urea accumulation". The Journal of Experimental Biology 205 (Pt 10): 1419–1427. PMID 11976353. 

• Burroughs, Frank (August 2006). "The Microfishery". Confluence: Merrymeeting Bay. Gardiner, Maine: Tilbury House. pp. 39–46. ISBN 978-0-88448-282-6. 
• Froese, Rainer, and Daniel Pauly, eds. (2006). "Osmerus mordax" in FishBase. June 2006 version.
• "Osmerus mordax". Integrated Taxonomic Information System. http://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=162041. Retrieved 19 June 2006. 
• Kovpa, N. E.; Skurikhina, L. A.; Kukhlevsky, A. D.; Oleinik, A. G.; Sendek, D. S. (2011). "Genetic divergence and relationships among smelts of the genus Osmerus from the Russian water". Russian journal of Genetics 47 (8): 958–972. doi:10.1134/S1022795411080102. 
• Robinson, J.L.; J.R. Hall, M. Charman, K.V. Ewart, W.R. Driedzic (2011). "Molecular Analysis, Tissue Profiles, and Seasonal Patterns of Cystolic and Mitochondrial GPDH in Freeze-Resistant Rainbow Smelt (Osmerus mordax)". Physiological and Biochemical Zoology 84 (4): 363–376. doi:10.1086/660162. PMID 21743250. 
• Roth, B.M.; T.R. Hrabik, C.T. Solomon, N. Mercado-Silva, T.F. Kitchell (2010). "A simulation of food-web interactions leading to rainbow smelt Osmerus mordax domance in Sparkling Lake, Wisconsin". Journal of Fish Biology 77 (6): 1379–1405. doi:10.1111/j.1095-8649.2010.02764.x. PMID 21039511. 
• Shaw, J. L.; Curry, R. A. (2011). "Ontogenetic divergence of growth among rainbow smelt morphotypes". Environmental Biology of Fishes 92 (2): 217–227. doi:10.1007/s10641-011-9835-x. 
• "Species profiles: Life histories and environmental requirements of coastal fishes and invertebrates". U. S. Fish and Wildlife Service. Biol. Rep. 82 (11). 1983. 
• Wyatt, L. H.; Baker, Al L.; Berlinsky, D. L. (2010). "Effects of sedimentation and periphyton communities on embryonic Rainbow Smelt, Osmerus mordax". Aquatic Sciences 72 (3): 361–369. doi:10.1007/s00027-010-0129-8. 

External links

• Michigan DNR Fish Identification
• Species fact sheet by Earl J.S. Rook
• Nova Scotia Department of Agriculture and Fisheries factsheet
• U.S. Geologic Survey Nonindigenous Aquatic Species page