Macrhybopsis gelida

Geographic Range

Sturgeon chub , Macrhybopsis gelida , have been found throughout the midwestern United States. They occupy 14 different states which are connected by the Missouri and Mississippi rivers and other connecting water systems. Some sturgeon chub populations can be found in Louisiana and as far north as Montana near Great Falls. They are not considered a migratory species. Currently, M. gelida inhabit about 1,155 miles of the Missouri River whereas historically it would range as much as 2,100 miles of the same river.

• Biogeographic Regions
• nearctic nearctic
  • native native

Habitat

Sturgeon chub habitat is very similar to sicklefin chub, Machrybopsis meeki . Sturgeon chub prefer rivers with high turbidity and moderate to strong current, large in size and not fragmented which plays a big role in their reproductive cycle. Rivers with low turbidity cause a disadvantage for sturgeon chub (what are these disadvantages?)because of these requirements they are primarily found in the main channels of the Missouri and Mississippi Rivers with gravel substrates (particle size of 2-16mm). They also prefer shallow depths and slower velocity currents (.89 m/s) compared to sicklefin Chub.

• Habitat Regions
• temperate temperate
• freshwater freshwater

• Aquatic Biomes
• rivers and streams

Physical Description

Since sturgeon chub live in rivers with high current, their bodies are thin and streamlined, they also have large fins, small eyes and the body and fin are covered with external papillae. The body coloration ranges from brown to blue for the back while the sides and bottom could range from silver to white. It has a ventral mouth while the snout is long and overhangs the mouth which is a characteristic that lead to its common name. The eyes are found on the dorsal sides but due to high turbidity of the environment, the eyes have little value while the external papillae are its primary sensory for finding resources. These fish do not display any sexual dimorphism throughout the seasons.

• Other Physical Features
• ectothermic ectothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• sexes alike

Development

Studies on sturgeon chub have concluded during the first year, the fish could grow up to 25- 48 mm and by year two they plateau at 86 mm. After age two it is difficult to correlate length and age for M. gelida also the average mass ranges from .075-5.50 grams. Across its geographic range, it is noted there is little to no difference length or mass development.

Reproduction

Little is known about the mating systems of sturgeon chub, they do spawn multiple times during the summer months which starts as early as May and ends late August. Female M. gelida will produce more eggs every year starting with 1,375 eggs as a second-year female up to 2,000 eggs as a fourth-year female and few have been observed to produce as much as 5,3100 eggs. The females will spawn over gravel and in water temperatures of 18.3- 22.7 ℃ within a pelagic are of a moving body of water. The eggs are semi-buoyant shortly after fertilization but will sink to the rock bed if there is no current, stream movement is key for dispersal. Also, the eggs are not adhesive so they will not stick to any substrate.

• Mating System
• polyandrous polyandrous

Sturgeon chub is a pelagic spawning cyprinid but, unlike other species do not migrate for spawning, rather will swim upstream and disperse eggs to be carried back down stream. This is behavior is thought to be linked to the declining resources of the habitat and the eggs are to be carried to a more enriched habitat.

• Key Reproductive Features
• seasonal breeding seasonal breeding
• sexual sexual
• fertilization fertilization
  • external external
• broadcast (group) spawning

There have not been any observations of parental care since the eggs are carried by the currents of large rivers into new areas.

• Parental Investment
• no parental involvement

Lifespan/Longevity

Sturgeon chub lifespan is about five years old while a few cases have reported chubs to be as old as seven years.

Behavior

Sturgeon chub are usually found in groups but do not appear to be territorial since their eggs are dispersed and carried by the current. While in groups it is noted sturgeon chub groups contain all age groups in different velocity rivers.

• Key Behaviors
• natatorial natatorial
• motile motile
• social social

Communication and Perception

• Perception Channels
• tactile tactile
• chemical chemical

Food Habits

Sturgeon chub is believed to be a carnivorous fish, its feeding habits so far have not been completely observed and documented, but from stomach samples there was exoskeletons present. Unfortunately, these specimens were unidentifiable while the black fly pupa Simulium sp. has been found in M. meeki . Since the sturgeon chub’s body is covered in external papillae, it uses it to sense prey in the turbid waters and mainly be a bottom feeder.

• Primary Diet
• carnivore carnivore
  • insectivore insectivore

• Animal Foods
• insects

• Foraging Behavior
• stores or caches food stores or caches food

Predation

There is little predation on the sturgeon chub since it is found in turbid waters. Sauger ( Sander canadensis ), walleye ( Sander vitreus ), and northern pike ( Esox lucius ) have been found preying on this fish. In one study, it was found that flathead chub ( Platygobio gracilis ) prey on sturgeon chub and sicklefin chub but not significantly. Sauger ( Sander canadensis ) diets comprised of only 16 percent of both fishes. There has been only one report of a sturgeon chub hosting black spot disease ( Uvulifer species).

• Anti-predator Adaptations
• cryptic cryptic

Ecosystem Roles

So far there is no research which pinpoints the niche this fish has in the ecosystem, it has few predators and little competition due to the habitat it lives in. Due to what it preys on, it could be a population stabilizer of aquatic invertebrates.

Economic Importance for Humans: Positive

Right now, there is no data to point any importance to humans, yet they could be used by local fisherman as bait.

• Positive Impacts
• food food

Economic Importance for Humans: Negative

Sturgeon chub populations appear to not negatively impact human activity while there is no research yet, this fish's habitat is found on remote turbid rivers.

Conservation Status

According to ICUN Red List, sturgeon chub are currently least concern. In the early 1990’s, they were considered vulnerable. The U.S. Fish & Wildlife Service list them as not listed, but there is a petition for move to threatened status.

Additional Links

Encyclopedia of Life

Contributors

Anthony Tejada (author), Minnesota State University Mankato, Robert Sorensen (editor), Minnesota State University, Mankato.

References

Hildyard, A. 2001. Endangered Wildlife and PLants of the World, Volume 2 . New York: Cavendish Square Publishing. Accessed April 05, 2017 at https://books.google.com/books?id=Lz9OvdnTGzoC&printsec=frontcover&dq=Endangered+Wildlife+and+Plants+of+the+World,+Volume+2&hl=en&sa=X&ved=0ahUKEwicscWdro7TAhVJxYMKHe2aBEAQ6AEIGjAA#v=onepage&q=Endangered%20Wildlife%20and%20Plants%20of%20the%20World%2C%20Volume%202&f=false .

Iowa River Information System, 2006. "Sturgeon chub-Macrhybopsis gelida" (On-line). Accessed March 15, 2017 at http://maps.gis.iastate.edu/iris/fishatlas/IA163866.html .

Miller, E., B. Gress. 2017. "Sturgeon Chub" (On-line). Accessed March 15, 2017 at http://www.gpnc.org/stchub.htm .

Montana Natural Heritage Program and Montana Fish, 2017. "Montana Field Guide" (On-line). Accessed March 15, 2017 at http://fieldguide.mt.gov/speciesDetail.aspx?elcode=afcjb53020 .

NatureServe, 2014. "Macrhybopsis gelida" (On-line). Accessed March 15, 2017 at http://www.iucnredlist.org/details/12583/0 .

Rahel, F., L. Thel. 2004. "Sturgeon Chub (Maecrhybopsis gelida): A Technical Conservation Assessment" (On-line). Accessed April 05, 2017 at https://www.fs.usda.gov/Internet/FSE_DOCUMENTS/stelprdb5206786.pdf .

Wildlife Guardians, 2016. "PETITION TO LIST THE Sturgeon Chub (Macrhybopsis gelida) and Sicklefin Chub (Macrhybopsis meeki) UNDER THE U.S. ENDANGERED SPECIES AC" (On-line). Accessed March 15, 2017 at http://www.wildearthguardians.org/site/DocServer/Sturgeon_SicklefinChubPetition8_11_16.pdf?docID=17346 .