Spotted Gar

Lepisosteus oculatus

Spotted_Gar_Mingo_10-9-08.jpg

Spotted gar, closeup of head, held in a fisher’s gloved hands, at Mingo NWR
The spotted gar has many well-defined roundish black spots on top of the head and on the paired fins. It is rather common in Missouri’s Bootheel lowlands.
Noppadol Paothong
Family

Lepisosteidae (gars) in the order Lepisosteiformes (gars)

Description

Gars are elongated, cylindrical fish with long snouts with numerous prominent teeth. The body is covered with hard, diamond-shaped scales. The spotted gar has many well-defined roundish black spots on top of the head and on the paired fins. Upperparts are brownish or olive, grading to white below, with well-defined roundish black spots on top of the head, snout, an all of the fins. This gar is most similar to the shortnose gar, but note the differences in lateral line and diagonal row scale counts below.

Similar species: Missouri has four species of gars.

The shortnose gar (L. platostomus) is most similar, but lacks has well-defined roundish black spots on the top of the head and paired fins; the scales in a diagonal row, from the scale at the front of the anal fin to the scale on the midline of the back (both included) usually number 20–23 (while the spotted numbers 17–20), and lateral line scales usually number 60–64 (the spotted numbers 54–58).

The longnose gar (L. osseus) has a relatively longer, narrower snout than all our other gars: the least width of the snout goes more than 10 times into its length, and the width of the upper jaw at the nostrils is less than the eye diameter.

The alligator gar (Atractosteus spatula) has a short, broad snout: the distance from the tip of its snout to the corner of the mouth is shorter than the rest of the head, and the least width of the snout goes only about 3–5 times into its length; also, it is a very large fish, commonly exceeding 3 feet in length and 8 pounds in weight.

Size

Adult length: in our state, reaches about 36 inches; weight: to 8 pounds.

Habitat and conservation

Compared to other Missouri gars, the spotted gar is less tolerant of continuous turbidity, and it shows a greater affinity for submerged aquatic vegetation. It is most abundant in quiet, clear waters having much aquatic vegetation or standing timber, and it is most common in our state in the lowlands of the Bootheel. Mingo Swamp is one place to see this species.

Gars are generally associated with warm, sluggish backwaters and are often seen basking quietly in the sun just beneath the surface. They frequently rist to the surface, opening and closing the jaws with a loud snap, then sinking below the surface. This behavior allows them to swallow air into their swim bladder, which is connected to the throat and is richly supplied with blood vessels — thus, the swim bladder functions much like a lung. This adaptation helps them survive in still or slow waters with relatively low oxygen levels.

Foods

A study of this species in Mingo Swamp revealed that young spotted gar eat mosquito larvae and small crustaceans. They begin eating fish at an early age, and mosquitofish and topminnows are their first principal prey. As adults, gizzard shad made up 90 percent of the adult spotted gar’s diet; the rest of the diet comprised freshwater shrimp, crayfish, and insects.

Distribution in Missouri

The spotted gar is rather common and widely distributed in the Bootheel lowlands of southeastern Missouri; its range also penetrates for short distances into the adjacent Ozarks. It probably occurs sporadically along the entire Mississippi River, but few records exist. It occurs in the Neosho River in southeast Kansas and has been observed in a small stream in the Neosho River drainage in southwestern Dade County.

Status

Non-game species. It is not abundant anywhere in Missouri. It is outnumbered at most localities by the shortnose or longnose gar.

Life cycle

In a study at Mingo Swamp, spotted gar were found to spawn around late April, in rapidly flowing water coming from a tract of flooded timber. By the latter part of May, the young had reached 2–3 inches in length. At one year old, they reach about 10 inches in length, and at age three, 20 inches. During the first two years, males grow more rapidly than females, but after that, females grow more rapidly, and they attain a greater size. In the Mingo Swamp study, a female at least 18 years old was found.

Human connections

Because they feed upon or compete for food with more “desirable” fishes, gars are often considered a worthless nuisance. But they may also serve as a natural control in preventing overpopulation and unbalanced fish populations, which improves fisheries and aquatic ecosystems in general.

Gar are seldom taken on hook and line and are rarely used for food. The hard, bony jaws of gars do not readily take a hook, and special techniques are required to capture them consistently with rod and reel. Because they often bask near the surface, gars provide a ready target for the bow hunter.

The eggs (roe) of gar are highly toxic to warm-blooded animals, including humans.

Some species of gars have been kept as aquarium fish, but this species — potentially reaching nearly a yard in length — would require a very, very large tank. In Missouri, anyone with a fishing permit can possess native nongame species in aquaria, if they are collected according to the rules outlined in the Wildlife Code of Missouri.

Ecosystem connections

Gars are a small group of primitive bony fishes that are a characteristic element in the fish fauna of the Mississippi Valley.

The armor of hard, diamond-shaped scales, and the hard, bony covering over the head and beak provide gars with a continuous, nearly inflexible sheath, making gars immune to the attacks of most wood-be predators.

The gar order (Lepisosteiformes) are an ancient group of fishes, with representatives dating back to the Late Jurassic period. Some ancestral (“primitive”) characteristics include the ganoid (hard, diamond-shaped, non-overlapping) scales, heterocercal tail (note how the spine extends upward into the top part of the tail), and unique characteristics of the pectoral girdle (bones supporting the pectoral fins).