Shortnose gar typically spawn in the spring during April, May and June, when water temperatures are between 16 and 21 °C. Females scatter large, yellowish-green eggs in quiet, shallow water among submerged vegetation or other underwater structures. A sticky adhesive holds the eggs together in clumps where they hatch after eight to nine days. The eggs are poisonous to birds and mammals, including humans (Montana Field Guide, 2019). The young remain in the yolk sac for another week, where they feed on insect larvae and small crustaceans. Young gar typically lead solitary lives and sexual maturity is achieved around three years of age when the gar reaches about 15 in (380 mm) in length (Montana Field Guide, 2019).

The diet of the shortnose gar is primarily composed of fish, though crayfish and insects are also utilized (Brown 1971). Young gar are known to feed on small insects and zooplankton, with fish entering the diet when gar are 1.25 inches in length. Gar are known as fierce predators of smaller fish, using ambush as a primary hunting technique.

Gar have the ability to survive in environments with very little oxygen and especially turbid conditions because of their specialized gas bladder, which have the ability to function like a lung to extract and use oxygen from swallowed air in addition to regulating buoyancy (Montana Field Guide, 2019).

Summary of species impacts derived from literature review. Click on an icon to find out more...

Environmental	Socioeconomic

Potential:
Anecdotal evidence has suggested that L. platostomus may have a negative effect on other fish species, including bluegill (L. macrochirus), green sunfish (L. cyanellus), young bass, and muskellunge (Becker 1983, Evermann and Goldsborough 1902). If it expands its range in the Great Lakes, it has the potential to hybridize with the spotted gar (L. oculatus), which is present in Lake Michigan tributaries and Lake Erie proper, and considered nationally threatened in Canada, endangered in Ohio, and of special concern in Michigan. 

There is little or no evidence to support that Lepisosteus platostomus has significant socio-economic impacts in the Great Lakes.

Realized:
Due to its high abundance and perceived nuisance, it was actively controlled in Lake Chautauqua, NY in the late 1890s (Evermann and Goldsborough 1902). Shortnose gar may adversely affect recreationally important fishes (e.g., young bass and muskellunge (Esox masquinongy)) (Evermann and Goldsborough 1902). The eggs of this species are poisonous to other animals, including humans (Montana Field Guide, 2019).

There is little or no evidence to support that Lepisosteus platostomus has significant beneficial effects in the Great Lakes.

Potential:
Although gars are not reported to be popular sport fishes, L. platostomus is noted by Becker (1983) as a good food fish (Scott and Crossman 1998). Becker (1983) suggested that L. platostomus could contribute to a balanced fish community.

Note: Check federal, state/provincial, and local regulations for the most up-to-date information.

Control
Biological
There are no known biological control methods for this species.

Physical
There are no known physical control methods for this species.

Chemical
Of the four chemical piscicides registered for use in the United States, antimycin A and rotenone are considered general piscicides, but no studies have been found of their effects on Lepisosteus platostomus (GLMRIS 2012).

Increasing CO2 concentrations, either by bubbling pressurized gas directly into water or by the addition of sodium bicarbonate (NaHCO3) has been used to sedate fish with minimal residual toxicity, and is a potential method of harvesting fish for removal, though maintaining adequate CO2 concentrations may be difficult in large/natural water bodies (Clearwater et al. 2008). CO2 is approved only for use as an anesthetic for cold, cool, and warm water fishes the US, not for use as euthanasia, and exposure to NaHCO3 concentration of 142-642 mg/L for 5 min. is sufficient to anaesthetize most fish (Clearwater et al. 2008).

It should be noted that chemical treatment will often lead to non-target kills, and so all options for management of a species should be adequately studied before a decision is made to use piscicides or other chemicals. Potential effects on non-target plants and organisms, including macroinvertebrates and other fishes, should always be deliberately evaluated and analyzed. The effects of combinations of management chemicals and other toxicants, whether intentional or unintentional, should be understood prior to chemical treatment. Other non-selective alterations of water quality, such as reducing dissolved oxygen levels or altering pH, could also have a deleterious impact on native fish, invertebrates, and other fauna or flora, and their potential harmful effects should therefore be evaluated thoroughly.

Note: Check state/provincial and local regulations for the most up-to-date information regarding permits for control methods. Follow all label instructions.