For those of us who were lucky enough to spend our childhood living on or near one of Michigan’s thousands of inland lakes, the scrappy bluegill, also sometimes referred to as bream or sun perch, was often the first fish that many of us ever caught while dangling a hook, worm, sinker, and bobber from the end of a flimsy cane pole. Native to the eastern half of the United States, due to the fact that the rapidly reproducing member of the sunfish family gradually became one of North America’s most popular sport fish, and have therefore been intentionally introduced to many regions where they are not indigenous, bluegill now commonly inhabit the waters of lakes, lagoons, reservoirs, ponds, quarries, and rivers extending from Canada to northern Mexico.
Capable of growing to 9½ inches (.24 meter) in length, and achieving a weight of up to 12 ounces (340 grams), bluegill (scientific name: Lepomis macrochirus) may be differentiated from other commonly occurring members of the sunfish family by the six to eight dark vertical bars that adorns both sides of their compressed body, a namesake pale blue spot on the upper most lobe of their gill cover, a relatively small head and mouth, a dorsal fin that features nine to eleven spines, and by an anal fin defined by three spines. Bluegill possess an upper body that is dark olive-green in color that gradually blends to colors ranging from lavender, brown, copper, or orange on the sides, and a reddish-orange or yellow belly. It is interesting to note that adult male bluegills may be distinguished from the females of the species by the presence of brighter, more tense coloration patterns.
Preferring quiet waters found in small to mid-sized inland lakes or ponds, bluegills are most often observed in large numbers within habitats ranging from dense submerged aquatic plant stands located near the drop-off in water depths of up to ten feet to areas hosting shade induced cooler waters located under docks, swimming rafts, or overhanging tree branches. In addition to habitats defined by complex vegetative or woody structure that provide protection from predation, bluegills prefer habitats that are capable of supporting their voracious, non-stop foraging upon insects, insect larvae, small crustaceans, and worms.
Reaching sexual maturity within their first two years of life, bluegills are capable of achieving and sustaining prolific rates of reproduction. Responding to the arrival of late spring or early summer, bluegill begin their annual reproductive cycle as water temperatures reach 70° F (21° C). The process begins as male bluegills use their tail to create a sediment free dish shaped nest lined with gravel and stone in water depths ranging from 1.5 to 4 feet (.45 – 1.21 meter). Given the fact that bluegills are colonial nesters, areas of inland lakes characterized by ideal breeding habitat comprised of flat or gradually sloping areas of shallow water interspersed with dense aquatic plant growth, and/or woody debris will often host hundreds of the saucer shaped nests. Depositing their eggs within the stone and gravel lined areas of several adjacent nests, mature female bluegills are capable of producing up to 80,000 eggs per year. The survival of each nest’s offspring is promoted by the fact that females and males make genetic contributions to multiple nests. Following the creation of nests, and the deposition and fertilization of eggs, male bluegills aggressively guard their respective nests from predators, and help promote the viability of the fertilized eggs by preventing sediment from accumulating within the nest. Following a brief incubation period the eggs hatch, and the male of the species guards the hatchlings until they are mature enough to venture out of the confines of the nest, and into open water.