Msg 3 Posted: 09:15 PM 06/07/08 (CST)
Sunfish biology and identification|
The bluegill is Minnesota's largest and most popular sunfish. It is found in about 65 percent of the state's lakes and many of its slow streams, including the backwaters of the Mississippi. It is rare in the Lake Superior drainage.
Appearance varies considerably among individuals, as is true with most sunfish. Most bluegill are light to dark olive, though older fish may have a purplish tinge. Cheeks and gill covers are often bluish and the ear flap is black. The rearward edge of the soft portion of the dorsal fin carries a dark blotch. Breeding males are marked by bright blue and orange. Females and younger fish are less colorful and are often marked by dark vertical bars on their olive backs. Though they occasionally exceed a pound, an 8-inch bluegill is considered large.
the bluegill spawns from late May or through much of the summer in water temperatures of 67 to 80 degrees. The male fans out a nest in firm-bottomed shallows, often within a colony of dozens of other nests. A single female can deposit more than 50,000 eggs. The male then guards eggs and fry.
The bluegill's mouth is small; it feeds mostly on aquatic insects and other small invertebrates. Young bluegill will feed in heavy weeds to avoid predators. Bluegill large enough to be of no interest to bass often swim freely in more open water, feeding heavily on tiny drifting zooplankton. This open-water feeding is especially common if bluegill must compete with pumpkinseed and green sunfish, which stay in the weeds. When food is scarce, bluegill will eat their own eggs.
Pumpkinseed sunfish. Pumpkinseed
Like the bluegill, the pumpkinseed lives in many of Minnesota's lakes and streams. This popular sunfish is nearly as large as the bluegill. The pumpkinseed can be distinguished from the bluegill by the bright orange spot at the tip of the ear flap and the lack of a dark blotch on the soft portion of the dorsal. Breeding males are particularly colorful; their cheeks and gill covers are marked by wavy bright blue bars. Identifying and distinguishing sunfish is complicated by frequent hybridization.
The pumpkinseed spawns from May until well into the summer, nesting in colonies and defending its nests, much as bluegill do. In fact, pumpkinseed sometimes build nests in bluegill colonies. The pumpkinseed eats aquatic insects and other invertebrates. It uses its specially adapted teeth to feed heavily on snails.
Drab in comparison to others of this tribe, the green sunfish is also distinguished by a mouth far larger than is typical of other sunfish. The ear lobe is black with a pale margin. The green sunfish is common in many lakes throughout the state and thrives in creeks. It tolerates greater turbidity and lower dissolved oxygen than bluegill or pumpkinseed.
The green sunfish usually is far smaller than pumpkinseed or bluegill, though hybridization with the larger species produces larger fish. Spawning times and habits are similar to those of other sunfish.
Like the bluegill, the green sunfish eats aquatic insects and other invertebrates and small fish. Because of its larger mouth, the green sunfish may eat larger critters than a bluegill of equal size, thus reducing competition between the species.
The orangespotted is the smallest Minnesota sunfish, rarely reaching 4 inches. It is on of our most colorful species. Spawning males carry orange-red lines of the cheeks and gill covers. Their bellies and lower fins are reddish. Ear lobes are dark with a pale border. Spawning habits are similar to those of other sunfish. Found in southern Minnesota, the orangespotted sunfish is too small to be popular with anglers. It is more tolerant of pollution and turbidity than other sunfish. Declines in water quality enable the orangespotted sunfish to extend its range while more desirable sunfish decline.
White crappie. Black and White crappie
The black crappie and white crappie are among Minnesota's most popular fish. In the angler's creel, the black crappie probably ranks second behind the bluegill.
The black crappie is the more widely distributed of the two closely related species, occurring in most lakes throughout the state. The black crappie prefers deeper, cooler, clearer water than the white crappie does.
The two species are difficult to distinguish. The black crappie is generally darker overall and has seven or eight spines in its dorsal fin. The white crappie, on the other hand, often has markings arranged in vertical bars. It usually has five or six dorsal spines. The two species are similar in size; a 2-pound fish is unusually large.
Spawning habits for the two crappie species are similar. They spawn in May and June, in water temperatures in the mid-60s, in water up to 6 feet deep. Males build and guard nests in colonies. They mature early and are prolific; a large female may produce well over 100,000 eggs. Crappie are prone to stunting. Because a strong year-class often dominates in a lake, crappie often appear to be all of the same size. When these fish of a strong year-class grow large, the lake can gain a reputation as a crappie hot spot and then fade into mediocrity as a younger year class takes over.
Young crappie eat small aquatic invertebrates. Adults can continue to feed on plankton but usually eat a lot of small fish as well. Crappie may compete with walleye to some degree because their habits are similar. Both species travel open water in schools, feeding on similar foods at night, dawn and dusk.
The most effective management is the protection of habitat and maintenance of good predator-prey balance in the lake.
Rock bass. Rock bass
Stout and heavy in comparison to the sunfishes and crappies, the rock bass has red eyes and brassy flanks with black spots. A large rock bass measures about 10 inches and weighs about a pound.
The rock bass spawns in the spring, when the water temperature ranges from the high 60s into the 70s. The male fans out a nest in coarse sand or gravel and guards the eggs and fry. It lives in many lakes and streams in Minnesota, generally preferring well-oxygenated, hard water walleye lakes and walleye- centrarchid lakes and the creeks associated with them. The rock bass prefers boulder and sand bottoms. It eats small fish, insects, crayfish and other invertebrates.
Rock bass require little management other than the protection of its habitat from pollution and other environmental degradation.
White Bass White bass and yellow bass
The panfish previously discussed in this brochure and centrarchids, or "spiny-rayed" fishes, and are closely related to largemouth and smallmouth bass. The white and yellow basses, despite their names, are not related to any of these. They are related to the much larger striped bass, a native of the Atlantic Ocean that has been stocked in freshwater but does not occur in Minnesota.
The white and yellow bass resemble one another, but as their names suggest, they are different colors. The white bass has separated dorsal fins, the second anal spine is one-third the length of the head, and the seven longitudinal stripes under the dorsal fins are solid. The yellow bass has joined dorsal fins, the second anal spine is half the length of the head, and the seven longitudinal stripes are broken. both are deep bodied and occasionally exceed 2 pounds.
The yellow bass is limited to the backwaters of the Mississippi below Lake Pepin. The white bass is common in the Minnesota River, The St. Croix below Taylors Falls, The Mississippi below St. Anthony Falls and major tributaries, such as the Cannon and Zumbro rivers. It also occurs in reservoirs on these river systems and in several lakes in southern Minnesota. Because of its greater size and abundance, the white bass is a more important sport fish than the yellow bass. Though the following remarks apply to the white bass, they are generally true of the yellow bass as well.
White bass spawn over gravel bars in late April to June, when water temperature ranges from 55 to 79 degrees. Mass upstream spawning runs in the Mississippi and its major tributaries provide excellent fishing in April and May. The white bass is extremely prolific; a large female may lay more than 500,000 eggs. No care is given the eggs or fry, and few survive. The fish continue to swim in schools through the summer. Both species occupy rather open water, often near the surface. Adults feed on zooplankton, aquatic insects and small fish. Gizzard shad are important forage in large rivers. Individual fish may travel more than 100 miles in their seasonal movements.
White bass require little management beyond habitat protection, and aren't introduced into waters where they don't already occur.