Critter Catalog

What do they look like?

Spotted gar grow to a maximum length of 91 cm, the average length is 76 cm. The body is cylindrical and often mistaken for a log lying in shallow waters. They are covered with hard, diamond-shaped scales and spots on the top of the head and fins. Females are generally larger than males.

• Other Physical Features
• ectothermic
• bilateral symmetry
• poisonous

• Sexual Dimorphism
• female larger

• Range mass

  1 to 4 kg

  2.20 to 8.81 lb

• Range length

  100 to 914 mm

  3.94 to 35.98 in

• Average length

  760 mm

  29.92 in

Where do they live?

Spotted gar are found throughout the rivers and streams that feed into Lake Michigan and Lake Erie, the Mississippi River, and rivers along the northern coast of the Gulf of Mexico from Texas east to Florida.

• Biogeographic Regions
• nearctic
  • native

What kind of habitat do they need?

Spotted gar prefer shallow open waters, usually 3 - 5 m deep, as well as stagnant backwater. They are often found near the surface basking near fallen logs, trees, or brush. This species is also shoreline-oriented, meaning it can be found near banks that include some sort of brush covering. Spotted gar are rarely found in areas that do not include some form of brush covering. (Snedden, et al., 1999)

• These animals are found in the following types of habitat
• temperate
• freshwater

• Aquatic Biomes
• lakes and ponds
• rivers and streams
• brackish water

• Wetlands
• swamp

• Other Habitat Features
• intertidal or littoral

• Range depth

  3 to 5 m

  9.84 to 16.40 ft

How do they grow?

Larval spotted gars hatch from eggs, and are about 2.5 cm long when they first emerge. They are slender and have a thread-like extension of the tail that vibrates, helping them to swim when they are small. They become fully developed by age 2. Females and males grow at different rates.

How do they reproduce?

Males gather in shallow (1.5 m) water with plants growing in it to compete for the largest females to mate with. Females allow more than one male to fertilize their eggs.

• Mating System
• polyandrous

Most eggs are laid in October, when females lay about 14,000 eggs. Larger females lay more eggs.

• Key Reproductive Features
• iteroparous
• seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual
• fertilization
  • external
• oviparous

• How often does reproduction occur?

  Females lay eggs once yearly.

• Breeding season

  Spawning occurs from February to June, varying with location.

• Range number of offspring

  1772 to 13789

• Average time to hatching

  7 days

• Average age at sexual or reproductive maturity (female)

  1 years

• Average age at sexual or reproductive maturity (male)

  1 years

Females deposit a lot of energy in the form of nutrients in their eggs to fuel the development of young. There is no parental care after the eggs are laid.

• Parental Investment
• pre-fertilization
  • provisioning
  • protecting
    • female

How long do they live?

It is not known how long spotted gar can live, but one study showed males living up to 8 years and females up to 10.

• Average lifespan
  Status: captivity

  18 years

  AnAge

How do they behave?

Spotted gar are mainly active at night. Often, this species will remain still near fallen trees or brush throughout the day. At night they emerge and search for prey. Occasionally, they go to the surface of the water to take air into their specialized swim bladder. This specialized bladder acts as a primitive lung and allows them to live in waters with low levels of oxygen.

• Key Behaviors
• natatorial
• nocturnal
• motile
• sedentary
• solitary
• territorial

• Range territory size

  0.9 to 162.73 km^2

• Average territory size

  2.65 km^2

Home Range

Home range sizes change with the seasons in spotted gar because water depths change. In spring, home ranges are about 20 times larger than in other seasons. Spotted gar move away from their home areas to spawn.

How do they communicate with each other?

Methods of communication among spotted gars aren't well-studied. They have a lateral line system that may help them sense prey in the turbid waters they live in.

• Perception Channels
• visual
• tactile
• chemical

What do they eat?

Spotted gars are ambush predators, eating mainly crayfish (47% of diet in one study). They forage at night under the cover of floating logs or vegetation. Spotted gar also eat other species of fish including sunfish, gizzard shad, crappies, bass, catfish, and shiners.

• Primary Diet
• carnivore
  • piscivore
  • eats non-insect arthropods

• Animal Foods
• fish
• insects
• aquatic crustaceans

What eats them and how do they avoid being eaten?

Adult spotted gars do not have many natural predators, except for other types of gars. Eggs and juvenile spotted gars are probably attacked by a number of fish predators, although the eggs of gar are potentially toxic to many species. The spotted pattern on these fish may act as camouflage.

• These animal colors help protect them
• cryptic

• Known Predators

  • alligator gars (Atractosteus spatula)

What roles do they have in the ecosystem?

Spotted gars are important predators of crayfish, other crustaceans, and smaller fish in the low-oxygen level waters they inhabit.

Do they cause problems?

Spotted gars sometimes attack popular game fish species, but there is no evidence that they effect populations of game fish. Existing studies show they prey on mainly non-game species.

How do they interact with us?

Juvenile spotted gar eat mosquito larvae. The species is not particular popular for sport fishing, although gars are considered good fish for eating.

• Ways that people benefit from these animals:
• food

Are they endangered?

Spotted gars are not generally considered in need of special conservation efforts, except at the edges of their range, where numbers have shrunk due to habitat destruction. They have not been evaluated by the IUCN. Spotted gar are Species of Special Concern in Michigan, Threatened in Canada (Ontario Province), and may have protected status in other states on the northern, eastern, and western limits of theirrange.

• IUCN Red List

  Not Evaluated

• US Federal List

  No special status

• CITES

  No special status

• State of Michigan List

  Special Concern

Some more information...

Contributors

George Hammond (editor), Animal Diversity Web.

Lana Hall (author), Radford University, Thomas Meade (author), Radford University, Drew Paulette (author), Radford University, Josh Albert (author), Radford University, Karen Powers (editor, instructor), Radford University.

Stephanie Givinsky (author), University of Michigan-Ann Arbor.

References

Hubbs, Carl L., and Lagler, Karl F. 1964. Fishes of the Great Lakes Region. University of Michigan Press.

Bowler, 1987. Recent observations of the distribution and status of the Freckled Madtom and the first record of Spotted Gar in Iowa. The Journal of the Iowa Academy Science, 3-4: 40-43.

Love, J. 2004. Age, growth, and reproduction of spotted gar Lepisosteus oculatus (Lepisosteidae) from the Lake Pontchartrain estuary, Louisiana. Southwestern Naturalist, 49/1: 18-23.

Ostrand, K., B. Braeutigam, D. Wahl. 2004. Consequences of vegetation density and prey species on Spotted Gar foraging. Transactions of the American Fisheries Society, 133/3: 794-800.

Pope, K., G. Wilde. 2003. Variation in spotted gar (Lepisosteus oculatus) mass-length relationships in Texas reservoirs. The Texas Journal of Science, 55.1: 43-49.

Schultz, K. 2004. Ken Schultz's Field Guide to Freshwater Fish. Hoboken, NJ: John Wiley & Sons, Inc. (US).

Snedden, G., W. Kelso, D. Rutherford. 1999. Diel and seasonal patterns of Spotted Gar movement and habitat use in the Lower Atchafalaya River Basin, Louisiana. Transactions of the American Fisheries Society, 128: 144-154.

Tyler, J., M. Granger. 1984. Notes on food habits, size, and spawning behavior of Spotted Gar in Lake Lawtonka, Oklahoma. Proceedings of the Oklahoma Academy of Science, Volume 64: 8.