ECOS Guide to the Ecology of the Northern Rockies

Name: Lepisostes platostomus - Shortnose Gar

Family: Lepisostidae (Gar)

Order: Lepisosteiformes (Gars)

Class: Osteichthyes (Gars)

Abundance: Rare.

Origin: Native.

Active Season: Year Round

Size:

average: 25 inches
largest: 29 inches

Colors: white-gray (underside), green (upperside), black (stripes on side of young), reddish-brown (upperside) yellow (sides)..

General Description: Gar are very ancient fish, though to have changed very little over the last million years. The shortnose gar is the only representative of the family found in Montana. It has rectangular scales that form a protective armor, a long bony head and beak, a single row of sharp teeth, a rounded tail, and a dorsal fin set far back on the body (near the tail). Interestingly shortnose gar can use their swim bladders like lungs. Thus, instead of relying solely on their gills to extract oxygen from water, shortnose gar can swallow air and extract the oxygen. This special adaptation allows the shortnose gar to survive in areas with very low dissolved oxygen in the water.

Similar Species: Because of their long bony beaklike snout and rectangular scales, shortnose gar are hard to confuse with other fish species. As well, they are only found in a few specific ponds in Montana.

Life History: Shortnose gar spawn in May or June, and instead of laying their eggs in a nest, they broadcast them over a large area. The eggs are yellow or green, and stick to aquatic vegetation. Interestingly, the eggs of shortnose gar are very poisonous to humans. Young gar hatch in only eight or nine days, and do not form schools. The young float near the surface while they eat and grow. They become sexually mature after about three years.

Distribution: Shortnose gar are found in the Mississippi drainage from the Gulf Coast north to Montana, and as far east as the Ohio River. In Montana, shortnose gar are found only in the dredge ponds below Forth Peck Reservoir. Because they have such a limited distribution in the state, they are considered a fish of special concern.

Habitat Description: Because they can use their swim bladder as a lung to extract oxygen out of the air, shortnose gar can survive in water bodies with very low dissolved oxygen. They are found in large rivers, backwaters, empoundments, turbid waters, and oxbow lakes.

Feeding Habits: Shortnose gar are voraciouse predators; often hiding and ambushing unsuspecting prey. They mostly eat other fish, but can also eat crayfish and aquatic insects.

Enemies & Diseases: The shortnose gar has very few enemies, as adults do not taste good, and eggs are poisonous.

Did You Know: In a study conducted in the Ozark Mountains, shortnose gar in rivers fed on cicadas that had fallen in the water and were floating downstream. Larger gar defended territories upstream, and thus recieved more of the floating cicadas.

Glossary:

Adaptation: a characteristic of an animal that helps it survive in it's habitat.
Dorsal fin: a fin along the midline of the back, usually midway between the head and tail fin.
Spawn: to deposit eggs.
Swim bladder: a specialized organ in fish that fills with air and keeps the fish bouyant.

Keywords:

References:

Holton, G. D. and H. E. Johnson. 2003. A Field Guide to Montana Fishes, Third Edition. Montana Fish, Wildlife & Parks, Helena, MT.

Montana Fish, Wildlife, and Parks Animal Field Guide. Shortnose Gar. http://fwp.mt.gov/fieldguide/detail_AFCBA01030.aspx.

Texas Parks and Wildlife. Wildlife Factsheets. Shortnose Gar. http://www.tpwd.state.tx.us/huntwild/wild/species/sng/.

Vokoum, J. C. 2000. Shortnose gar (Lepisosteus platostomus) foraging on periodical cicadas (Magicicada spp.): Territorial defense of profitable pool positions. American Midland Naturalist 143: 261-265.

Contributor:

Allison Greene


Home Plant Guide Insect Guide Bird Guide Mammal Guide Geology Guide Fish Guide Fish by Name Fish by Family Fish by Order Glossary of Fish Terms Amphibian Guide Reptile Guide Habitats Descriptions Maps Contributors ECOS Home		Physical Characteristics - General Description - Similar Species - Life History - Distribution - Habitat - Feeding Habits - Did You Know - Glossary - References Name: Lepisostes platostomus - Shortnose Gar Family: Lepisostidae (Gar) Order: Lepisosteiformes (Gars) Class: Osteichthyes (Gars) Abundance: Rare. Origin: Native. Active Season: Year Round Size: average: 25 inches largest: 29 inches Colors: white-gray (underside), green (upperside), black (stripes on side of young), reddish-brown (upperside) yellow (sides).. General Description: Gar are very ancient fish, though to have changed very little over the last million years. The shortnose gar is the only representative of the family found in Montana. It has rectangular scales that form a protective armor, a long bony head and beak, a single row of sharp teeth, a rounded tail, and a dorsal fin set far back on the body (near the tail). Interestingly shortnose gar can use their swim bladders like lungs. Thus, instead of relying solely on their gills to extract oxygen from water, shortnose gar can swallow air and extract the oxygen. This special adaptation allows the shortnose gar to survive in areas with very low dissolved oxygen in the water. Similar Species: Because of their long bony beaklike snout and rectangular scales, shortnose gar are hard to confuse with other fish species. As well, they are only found in a few specific ponds in Montana. Life History: Shortnose gar spawn in May or June, and instead of laying their eggs in a nest, they broadcast them over a large area. The eggs are yellow or green, and stick to aquatic vegetation. Interestingly, the eggs of shortnose gar are very poisonous to humans. Young gar hatch in only eight or nine days, and do not form schools. The young float near the surface while they eat and grow. They become sexually mature after about three years. Distribution: Shortnose gar are found in the Mississippi drainage from the Gulf Coast north to Montana, and as far east as the Ohio River. In Montana, shortnose gar are found only in the dredge ponds below Forth Peck Reservoir. Because they have such a limited distribution in the state, they are considered a fish of special concern. Habitat Description: Because they can use their swim bladder as a lung to extract oxygen out of the air, shortnose gar can survive in water bodies with very low dissolved oxygen. They are found in large rivers, backwaters, empoundments, turbid waters, and oxbow lakes. Feeding Habits: Shortnose gar are voraciouse predators; often hiding and ambushing unsuspecting prey. They mostly eat other fish, but can also eat crayfish and aquatic insects. Enemies & Diseases: The shortnose gar has very few enemies, as adults do not taste good, and eggs are poisonous. Did You Know: In a study conducted in the Ozark Mountains, shortnose gar in rivers fed on cicadas that had fallen in the water and were floating downstream. Larger gar defended territories upstream, and thus recieved more of the floating cicadas. Glossary: Adaptation: a characteristic of an animal that helps it survive in it's habitat. Dorsal fin: a fin along the midline of the back, usually midway between the head and tail fin. Spawn: to deposit eggs. Swim bladder: a specialized organ in fish that fills with air and keeps the fish bouyant. Keywords: References: Holton, G. D. and H. E. Johnson. 2003. A Field Guide to Montana Fishes, Third Edition. Montana Fish, Wildlife & Parks, Helena, MT. Montana Fish, Wildlife, and Parks Animal Field Guide. Shortnose Gar. http://fwp.mt.gov/fieldguide/detail_AFCBA01030.aspx. Texas Parks and Wildlife. Wildlife Factsheets. Shortnose Gar. http://www.tpwd.state.tx.us/huntwild/wild/species/sng/. Vokoum, J. C. 2000. Shortnose gar (Lepisosteus platostomus) foraging on periodical cicadas (Magicicada spp.): Territorial defense of profitable pool positions. American Midland Naturalist 143: 261-265. Contributor: Allison Greene