BioKIDS home

Kids' Inquiry of Diverse Species

Blue herring

Alosa chrysochloris

What do they look like?

Skipjack herring have a thin, compressed body that can be up to 21 inches long. These fish have a large mouth and pointed snout with a lower jaw that sticks out. Their jaw can be used to identify them from other similar species. Skipjack herring have teeth in both jaws as well as two to four rows on their tongue. Their back is gray and their sides and belly are silver or white. At times, skipjack herring look like they have a blue reflection coming from their sides. These fish have yellow eyes with protective eye lid covers. Skipjack herring also have scales known as "scutes". ("Skipjack Herring", 2012; MN DNR, 2013)

  • Sexual Dimorphism
  • sexes alike
  • Range mass
    420 to 1588 g
    14.80 to 55.96 oz
  • Average mass
    453 g
    15.96 oz
  • Range length
    250 to 550 mm
    9.84 to 21.65 in
  • Average length
    250-450 mm
    in

Where do they live?

Skipjack herring, which are also known as skipjack shad (Alosa chrysochloris), are found in the Red River drainage (Hudson Bay basin) and Mississippi River basin from central Minnesota, south to the Gulf of Mexico. They can also be found widely throughout the eastern United States, from Florida to Texas. These fish are also sometimes found in salty sea waters especially along the gulf coast. ("Alosa chrysochloris", 2009; Morrison, 2009; NatureServe, 2005)

What kind of habitat do they need?

Skipjack herring are large river fish that prefer to live in clear, deep, and swift waters over gravel or sand. These fish mostly travel in large schools, partly for protection from larger predatory species. Skipjack herring are usually not found on the bottom of the river, and they avoid muddy or cloudy waters whenever possible. They often "skip" along the surface of the water when they migrate in early spring. Large groups of skipjack herring are sometimes found in swift currents below dams. These fish spend most of their life in rivers and sometimes in coastal marine estuaries. Skipjack herring migrate upstream in the spring to spawn, sometimes traveling very long distances. The addition of dams in many areas prevents them from migrating further upstream. This has caused skipjack herring to disappear from areas where they were once present such as in Minnesota. (MN DNR, 2013; Morrison, 2009)

How do they grow?

Skipjack herring complete their entire life cycle in fresh water. Information about their spawning patterns is very limited; however, skipjack herring are thought to spawn in the deepest channels over coarse gravel or underwater sandbars. Juveniles eat zooplankton, insect larvae, and small fishes and continue eating more fish as they grow. Juvenile skipjack herring reach lengths of 75 to 150 mm during their first year of life. They are ready to reproduce when they are about 300 mm long. Immediately after hatching, skipjack herring are on their own and many are eaten by predatory fish. Juveniles that survive the first few months of life have an increased chance of survival. Skipjack herring usually stop growing after reaching 21 inches in length. ("Herring Family: Clupeidae", 2008; Hassan, 2013)

How do they reproduce?

Very little information is available regarding the specific spawning patterns of skipjack herring. In general, members of their family (Clupeidae) spawn in the spring, once water temperatures have warmed to between 11 and 27° Celsius. Before spawning, skipjack herring usually travel a long distance. Due their water temperature needs, spawning often happens earlier at lower latitudes and later at higher latitudes. Females reach the spawning grounds before males, where the oldest females spawn first. Since these fish travel in schools, they do not have a problem finding or attracting mates. These fish typically form mating pairs, or groups of three. Females drop their eggs in moderately deep, to very deep areas over gravel, while males fertilize them with sperm. ("Herring Family: Clupeidae", 2008)

Female skipjack herring are ready to reproduce in about three years, while males mature in about two years. Females lay between 100,000 and 300,000 eggs every spring after their migration. Directly after spawning, mature skipjack herring leave the spawning site. Larvae hatch in 58 hours at 17.2° Celsius. After hatching, larva are about 3.4 to 3.6 mm long. After the spawn, larval skipjack herring are immediately on their own. (Ross, 2001)

  • How often does reproduction occur?
    Skipjack herring breed once a year after the spring migration.
  • Breeding season
    Skipjack herring typically spawn from early May through July.
  • Range number of offspring
    100,000 to 300,000
  • Average number of offspring
    150,000
  • Range time to hatching
    3 to 6 days
  • Average time to hatching
    6 days
  • Range time to independence
    Immediatley (low) minutes
  • Range age at sexual or reproductive maturity (female)
    3 to 4 years
  • Average age at sexual or reproductive maturity (female)
    3 years
  • Range age at sexual or reproductive maturity (male)
    2 to 3 years

Right after spawning, skipjack herring leave the spawning grounds and return to their original habitat, giving no parental care to their young. Larval skipjack herring spend the summer in shallow waters and in the fall, they move to large groups in the main channel for protection. ("Skipjack Herring", 2012)

  • Parental Investment
  • no parental involvement

How long do they live?

Not much is known about the lifespan of skipjack herring. However, many species in their family (Clupeidae) commonly live to 10 years of age. Most skipjack herring do not live past the first few months of life, around 90% die within the first year of life. Once skipjack herring make it past the first year of life, their chances of survival begin to increase with their increasing size. The biggest threat to skipjack herring is predation, they make up the primary diet of many species. ("Herring Family: Clupeidae", 2008; Coad, 1997)

  • Typical lifespan
    Status: wild
    1 to 10 years
  • Average lifespan
    Status: wild
    6 years

How do they behave?

Schools of skipjack herring drive minnows to the surface so they can easily be captured and often leap out of the water when feeding. These fish often form large groups below dams in the spring, likely trying to migrate upstream to spawn. Skipjack herring vertically migrate daily, this means they move up and down the water column at certain times of the day in search of food. ("Assessment of Migratory Stocks", 2011; MN DNR, 2013)

Home Range

The home range of skipjack herring includes the Mississippi River. Skipjack herring migrate up tributaries to spawn, but they usually come back to the Mississippi River after the spawn due to the steady water levels, large main channel, and swift moving water. There is currently no information available regarding the territory size maintained by these fish. (MN DNR, 2013)

How do they communicate with each other?

Little to no information is known about the communication of skipjack herring besides their feeding and mating behavior. Their yellow eyes are thought to help them find other skipjack herring for mating. Likewise, their yellow eyes may also help them find prey in low light. ("Herring Family: Clupeidae", 2008)

  • Communication Channels
  • visual

What do they eat?

Skipjack herring eat plankton and small fishes, mostly minnows, goldeneyes, and gizzard shads. Skipjack herring also feed on insects such as mayflies and caddisflies. Feeding usually occurs in schools, this species commonly crowds minnows to the surface before preying upon them. (MN DNR, 2013; Ross, 2001)

  • Animal Foods
  • fish
  • insects

What eats them and how do they avoid being eaten?

Skipjack herring have many predators. Their biggest advantage over larger fish is that they travel in schools, making it harder for the predator to find them. However, this also means when they are found, the predator may go into a feeding frenzy, eating many at once. ("Alosa chrysochloris", 2009)

What roles do they have in the ecosystem?

Skipjack herring are an important host for the parasitic larvae of native ebony shell mussels. The loss of skipjack herring in the upper Mississippi River resulted in the loss of ebony shell mussels. Skipjack herring are also a major food source for predatory fish in the Mississippi River. (Ross, 2001)

Commensal or parasitic species (or larger taxonomic groups) that use this species as a host

Do they cause problems?

Skipjack herring are not known to create any negative effects for humans.

How do they interact with us?

Skipjack herring can be eaten by people, but they are generally considered a 'rough fish' because it is difficult to remove all of their bones. These fish are caught by commercial fisherman to sell and use for bait to catch other, more preferred game fish. Although by themselves skipjack herring do not have a large economic value, they provide a food source for many desired game fish. Game fishing is a very large industry and attracts people from all over the country. (Morrison, 2009)

Are they endangered?

There are currently no concerns for skipjack herring. Their population size is very stable except in areas where dams have cutoff their migration, near Minnesota and Wisconsin. (NatureServe, 2005)

Some more information...

Skipjack herring are the only host for the larval stages of two endangered mussel species in Minnesota, ebony shells and elephant-ears. Reestablishing these fish would allow ebony shell and elephant ear mussels to return to Minnesota. Lock and dam structures limit the spring migration of skipjack herring. To reestablish these fish in Minnesota, fish passage features such as ladders or lifts will be needed at several lock and dam sites between Iowa and central Minnesota. (MN DNR, 2013)

Contributors

Dylan Chandler (author), Minnesota State University, Mankato, Robert Sorensen (editor), Minnesota State University, Mankato, Leila Siciliano Martina (editor), Animal Diversity Web Staff.

References

U.S. Geological Survey. Alosa chrysochloris. 489. Gainesville, Florida: U.S. Department of the Interior. 2009.

2011. "Assessment of Migratory Stocks" (On-line). Accessed March 26, 2013 at http://www.fao.org/docrep/W5449E/w5449e0d.htm.

2008. "Herring Family: Clupeidae" (On-line). Accessed March 25, 2013 at http://images.library.wisc.edu/EcoNatRes/EFacs/FishesWI/reference/econatres.fisheswi.i0022.pdf.

2012. "Skipjack Herring" (On-line). Accessed March 25, 2013 at http://www.seagrant.wisc.edu/home/Default.aspx?tabid=605&FishID=135.

Coad, B. 1997. "Shad Journal" (On-line). Accessed March 26, 2012 at http://www.cbr.washington.edu/shadfoundation/shad/JOURNAL2/vol2n4.pdf.

Hassan, C. 2013. "Skipjack herring" (On-line). Accessed March 25, 2013 at http://txstate.fishesoftexas.org/alosa%20chrysochloris.htm.

MN DNR, 2013. "Species profile: Minnesota DNR" (On-line). Accessed March 25, 2013 at http://www.dnr.state.mn.us/rsg/profile.html?action=elementDetail&selectedElement=AFCFA01030.

Morrison, S. 2009. Skipjack Herring. Wildlife Diversity Notebook, Spring 2009: 9.

NatureServe, 2005. "Comprehensive Report Species" (On-line). Accessed March 25, 2013 at http://www.tnfish.org/SpeciesFishInformation_TWRA/Research/SkipjackHerring_AlosaChrysochlorisInformation_NS.pdf.

Ross, S. 2001. The Inland Fishes of Mississippi. Mississippi: Sport Fish Restoration.

 
University of Michigan Museum of ZoologyNational Science Foundation

BioKIDS home  |  Questions?  |  Animal Diversity Web

Chandler, D. 2014. "Alosa chrysochloris" (On-line), Animal Diversity Web. Accessed May 20, 2024 at http://localhost:2015/accounts/Alosa_chrysochloris/

BioKIDS is sponsored in part by the Interagency Education Research Initiative. It is a partnership of the University of Michigan School of Education, University of Michigan Museum of Zoology, and the Detroit Public Schools. This material is based upon work supported by the National Science Foundation under Grant DRL-0628151.
Copyright © 2002-2024, The Regents of the University of Michigan. All rights reserved.

University of Michigan