The spotted gar showcases a distinct appearance with an abundance of dark spots adorning its head, fins, and elongated dart-like body. With an elongated mouth filled with needle-like teeth, the spotted gar is well-equipped to capture other fish and crustaceans, making it a formidable predator in its habitat. This species is one of the smallest among the seven gar species found in North America, typically growing between 2 to 3 feet (0.61 to 0.91 meters) in length and weighing around 4 to 6 pounds (1.8 to 2.7 kilograms). Notably, gars possess diamond-shaped, thick enamel (ganoid) scales, which provide them with exceptional protection. The name Lepisosteus is derived from the Greek word for "bony scale," aptly describing the unique physical attribute of this fish.
The spotted gar has a wide distribution range across North America, spanning from southern Ontario westward to the Devils River in Texas and eastward to the northern coast of the Gulf of Mexico. Its range extends southeastward to the lower Apalachicola River in Florida. However, it is important to note that the gar population is relatively smaller in the northern regions, and their habitat in Lake Erie is under threat due to habitat destruction and pollution. Conversely, the spotted gar is more commonly found in the southern waters, such as the Mississippi River basin from southern Minnesota to Alabama and western Florida. Historical records indicate that the spotted gar once resided in the Thames and Sydenham Rivers in Ontario, Canada. Unfortunately, their population in these areas has declined due to the loss of specific habitat requirements, particularly clear pools with aquatic vegetation.
Spotted gars primarily inhabit clear, slow-moving, shallow waters, including creeks, rivers, and lakes. Although their preference lies in such freshwater habitats, they occasionally venture into brackish or slightly salty waters. Notably, the gars have developed a remarkable adaptation to low oxygen levels created by slow-moving water. They possess the ability to gulp air and transfer it to a primitive lung known as a gas bladder.
The spotted gar demonstrates a voracious predatory nature, relying on its sharp-toothed beak to effectively capture fast-moving prey. Extensive diet studies have revealed that the spotted gar feeds on a variety of organisms, including four species of fish: golden topminnow, warmouth, bluegill, and spotted sunfish. These fish species contribute to approximately 18.1% of the spotted gar's total food volume. Additionally, shrimp constitutes a significant portion, accounting for 57.5% of the stomach content. Other invertebrates make up the remaining 23.6% of the gar's diet. Furthermore, spotted gars are known to consume insect larvae and algae, showcasing their versatility in food sources.
Within the aquatic food chain, gars play a pivotal role as primary predators. They engage in intricate food chain dynamics, such as preying on herbivorous fish that feed on algae and being consumed by other carnivorous fish. However, gars have relatively few natural predators, with only carnivorous fish posing a threat, mainly during the early stages of their life. One notable competitor of the spotted gar is the bowfin (Amia calva), as both species share similar ecological niches.
The movement patterns of spotted gars vary with the seasons, exhibiting higher rates during summer compared to fall and winter. Moreover, their movement is more prominent at night rather than during dawn and dusk. Temperature plays a crucial role in their activity levels and territorial range. Warmer water temperatures in spring and summer prompt increased travel, while colder seasons see reduced movement. Interestingly, spotted gars tend to consume approximately 70% of their food intake at night, highlighting their nocturnal feeding behavior.
Spotted gars engage in spawning during the spring months, specifically in April, May, and June, when the water temperature ranges between 21.0 and 26.0 °C (69.8 and 78.8 °F), depending on the location. They prefer shallow water with ample vegetation and cover for successful reproduction. Females possess the ability to mate with multiple partners, and they generally surpass males in size.
A female spotted gar can lay up to approximately 20,000 eggs, although the average number falls around 13,000 eggs. These eggs, typically green in color, possess an adhesive coating that enables them to attach to aquatic vegetation. To protect against prospective predators, the eggs contain toxins. After a period of 10 to 14 days, the eggs hatch, leaving the young gar in a vulnerable state.
Males tend to reach sexual maturity between the ages of two and three, while females reach maturity between three and four years. The average lifespan of males is approximately 8 years, whereas females have a slightly longer average lifespan of 10 years. The maximum recorded lifespan for a spotted gar is 18 years. Notably, Teri, a spotted gar of unknown sex, resided at the Museum of Natural Sciences of the University of Saskatchewan for over 20 years, surpassing the typical lifespan.
Human activities have significantly impacted the spotted gar species, primarily through habitat destruction, degradation of aquatic vegetation, and water contamination. Chemical runoff and waste drainage into lakes and rivers contribute to chemical buildup and contamination, resulting in murky water and elevated levels of mercury or carcinogenic compounds in predatory fish. These anthropogenic factors directly affect the survivability of the spotted gar, as they require clear water pools for their habitat.
While the spotted gar is not currently listed as federally endangered by the U.S. Fish and Wildlife Service, it is designated as threatened by the Committee on the Status of Endangered Wildlife in Canada, emphasizing the need for conservation measures. The Species at Risk Act and the federal Fisheries Act in Canada protect the spotted gar in Canadian waters. The Habitat Stewardship Program for Species at Risk actively works toward safeguarding the spotted gar and its habitat. Management plans focus on enhancing water quality, minimizing pollution, and analyzing contaminated samples as part of comprehensive conservation efforts.