Life In Lake Atitlan (ati Divers, La Iguana Perdida, Guatemala)

Life in the Lake Black Crappie, Calico Bass (Pomoxis Nigromaculatus)

Description Crappie is a member of the sunfish family Centrarchidae, which includes many species of spiny-finned, freshwater fishes with deep, flattened bodies found throughout North America. Crappies are the largest of the sunfishes, reaching lengths of up to 30 cm/1 ft or more. There are two species, the white crappie (Pomoxis annularis) and the black crappie (Pomoxis nigromaculatus), though only black crappie are found in Lago de Atitlàn. The black crappie has a rounded body with a greenish back and silvery sides with mottled black markings. It is this mottled pattern that gives the black crappie its other common name: calico bass. Life span for this species is about seven years. Habitat and life cycle Black crappie is a schooling fish and lives in temperate ponds, lakes, streams, and resevoirs. Black crappie prefer fertile lakes with firm bottoms and lots of plants and underwater structures like logs, stumps and rocks.

By day, crappie tend to be less active and to concentrate around weed beds or submerged objects. They feed especially at dawn and dusk, moving into open water or approaching the shore. Adults feed mainly on smaller fish (including the young of their own predators), insects, crayfish and tadpoles. Young fish eat zooplankton (microscopic animals and other organisms including water fleas, mosquito larvae, paramecia, amoebas, etc.) and grow 5–7 cm/2–3 in. their first year. Black crappie are preyed on by any larger fishes, as well as by herons and turtles. Due to the species’ great range, breeding season varies by location, but breeding temperature is from 14–20 °C (58–68 °F). Crappie are sexually mature after 2–3 years. Black crappie spawn in the same way as bluegill and other members of the sunfish family: males first sweep out a nest in sand or gravel in water 1–2 m/3–8 ft deep. Females then lay up to 60 000 eggs in the nests before leaving the males to guard the eggs, which hatch after about a week. The newly hatched fish stay in the nest a few days while they develop a functional mouth, then move into the water column. Males stay with the young until they are able to start feeding.

The crappie’s common name (also spelled croppie or crappé), derives from the Canadian French “crapet.”

Life in the Lake Bluegill sunfish, Bream (Lepomis macrochirus) Description Bluegill, also commonly referred to as bream, is a member of the sunfish family (family Centrarchidae). It is a deep, flat-sided fish with a small mouth and long pectoral fins. Colouration varies, but the opercular flap (ear flap), an extension of the gill cover, is always blue-black and bluegills have a black spot near the back of the dorsal fin. Bluegill also have darker vertical bars along the sides of the body, though these are not always pronounced. The name comes from the bright blue edging on the gill rakers. Bluegill grow to a maximum length of approximately 40 cm/16 in. Specimens in the lake frequently reach 15–20 cm/7–10 in. Habitat and life cycle Bluegill’s preferred habitat is clear, temperate lakes with some rooted vegetation. This fish is native to a wide area of North America, from Quebec to northern Mexico, and has been widely introduced to stock game fish for anglers. Bluegill was introduced to Lago de Atitlàn along with the black bass in 1958 as a food source for the bass. The bluegill’s natural diet consists largely of small invertebrates and very small fish. Young bluegill mainly eat zooplankton or microscopic animals. Adults feed mainly on aquatic insects.

Bluegill is a schooling fish, with schools of 20–30 individuals. They are nest spawners and typically build nests in large groups. Males choose an area in shallow water (less than 1 metre/4 feet deep) and sweep out a saucer shaped nest with their tails. The females then lay 10 000–60 000 eggs in the nests, which are guarded by the males. The eggs usually hatch in about five days. During the nesting period males assume a very bold colouration. Some males assume the colouration of the female fish so that the males guarding the nests won’t be aggressive towards them, allowing the “sneaker” males to enter nests and spawn. The cities of San Francisco, New York and Washington have used bluegills for monitoring their water supply for toxins like pesticides, mercury, cyanide, heavy metals, fuel spills and phosphates. Fish cough by flexing their gills to expel unwelcome particles, like grains of sand or chemical residues, from their breathing surfaces; this flexing creates tiny vibrations in the water. Instruments in the water supply “listen” for these vibrations and note any unusual amounts of coughing coming from the fish.

Life in the Lake Convict cichlid, Zebra cichlid (Cryptoheros nigrofasciatus, formerly Archocentrus nigrofasciatus)

Description The convict cichlid is one of few native fishes left in Lago de Atitlàn. It is a moderately elongated, laterally compressed fish with an oval body shape. The body is white to blue grey, with a grey head and eight or nine dark vertical bars across the body. The belly may have orange or pink scales. Males grow to 15 cm/6 in, females to 12 cm/ 5 in. Males generally have longer, more flowing dorsal and anal fins, a steeper forehead and sometimes a head hump. Females have a rounder belly profile and are usually more colourful, especially during spawning season, when they develop a yellow-orange belly to attract their young. Habitat and life cycle The convict cichlid is found within Central America from Lake Atitlàn and Lake Amatitlan in Guatemala south to lakes in El Salvador, Costa Rica and Panama. Central America’s rocky lake habitat, formed by volcanic craters, provides deep, steep, rocky sides and hard, alkaline water.

The convict cichlid stays close to cover like roots, rocks and overhanging banks. Like most Central American cichlids, it is very territorial and aggressive. It is omnivorous, feeding on worms, crustaceans, insects, fish and plant matter. Males and females form strong pair bonds, pairing off after a mating dance. Both parents dig a pit in the gravel around their chosen nest site, which is usually a small cave or grotto. Spawns range from 50–100 eggs for fish less than a year old while older pairs may lay 300 eggs or more. Once fertilized, eggs are guarded by both parents. Females fan oxygenated water over them while males patrol the outskirts of the territory, chasing away intruders. The eggs hatch in about 3 days. The wriggling larvae may be moved by the parents to various pits dug in the lake bottom. A week later, the fry are free-swimming, but parents care for them for another 3-4 weeks. Convict cichlids are tireless parents, frequently exhibiting the following behaviours: Guarding: Both parents guard the fry, with the female staying closer to the fry while the male patrols the perimeter. Fry retrieval and cleaning: If a fry strays too far from the group, a parent will swim to it, take the fry in its mouth and return it to the school. Parents also clean fry by taking them in their mouths and “chewing” a bit before spitting them back out. Fin-digging and leaf-turning: Parents stir up food for the fry by wriggling in the gravel. They also turn over leaf litter on the bottom to expose invertebrate food items living on the undersides. Because the convict cichlid is very hardy, thrives in almost any water conditions, is easy to breed in captivity and exhibits remarkable parental behaviour, it is one of the most popular cichlids for aquarium hobbyists.

Life in the Lake Black bass, Largemouth bass (Micropterus salmoides) Description The name “black bass” is collectively used for three species of bass: the largemouth, smallmouth and spotted bass. Lago de Atitlàn’s black bass is the largemouth bass, Micropterus salmoides. The largest member of the sunfish family Centrarchidae, it is bronze to green with dark blotches forming a stripe along the sides of the body. Because the upper jaw extends behind the eye, its mouth is relatively large, as the name suggests. Black bass typically reach sexual maturity at about 25 cm/10 in length, which can be as soon as one year. In two years, the bass have attained record size, with an average weight of 4kg/9lbs. Habitat and life cycle Black bass survives well in almost any clearwater environment. Its original distribution covered most of the U.S and Canada east of the Rocky Mountains, but the species has been introduced into most of Mexico and Central and South America, as well as a wide area of Europe. The black bass spends most of its time in its home range, a small, concealed area of deep cover near logs, docks, underwater ridges, submerged brush and rocks, quietly waiting for food to come its way.

Black bass has a voracious appetite and will feed on anything that moves, swallowing its prey whole. In its native range, it is such a fierce predator that it has caught and killed birds such as swallows, warblers and redwinged blackbirds as they fly near the surface of the water. Starting at about 5 cm/ 2 in. length, they begin to prey on smaller fish, frogs, snails, worms, insects, crayfish, crabs, lizards and young birds. In their native range, they contribute to the overall health of the ecosystem by keeping bluegill and other fish populations under control. Introduced to Lago de Atitlàn in 1958, the bass have eliminated many other species of fish from the lake, and have almost certainly played a role in the disappearance of the giant grebe, an endemic species now extinct. During spawning season, the male selects a sunny spot in quiet shallows up to 2 m/8 ft deep, courts a female, and persuades her to deposit eggs in his nest. Each female lays up to 40 000 eggs; once the male has fertilized the eggs, he guards them until they hatch 5–10 days later. Once hatched, the young begin feeding on plankton and insect larvae. In many parts of the United States, black bass is the most popular game fish; an estimated 26 million Americans fish for this species. The meat is light, flaky and tasty, with low oil content.