Mylopharodon conocephalus facts for kids
Quick facts for kids Hardhead |
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Mylopharodon
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conocephalus
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The Mylopharadon conocephalus, usually called the hardhead, is a type of freshwater fish. It belongs to the Cyprinidae family, which includes carps and minnows. This fish is special because it is found only in California. It's also the only species in its group, called Mylopharadon.
Contents
About the Hardhead
The hardhead fish has a long, thin body. Its back is brown to dark bronze, with bigger fish being darker. Its sides are shiny silver. The fin on its back (called the dorsal fin) starts behind its belly fins (called pelvic fins). It has 69 to 81 scales along its side, which is called the lateral line. The dorsal fin has 8 rays, which are like bony supports.
Its mouth is large and at the very end of its pointed snout, reaching back to the front of its eye. Hardheads grow to about 30 centimeters (12 inches) long. Young hardheads are silvery. During spring, which is their breeding season, adult male hardheads grow small white bumps on their heads and along their bodies.
Where Hardheads Live
Hardheads live in many parts of the Sacramento River and San Joaquin River areas in California. They are common in streams found in the foothills. The southernmost place they live is the Kern River in Kern County, California. They can be found as far north as the Pit River area in Modoc County, California.
You won't find hardheads in the Clear Lake basin. They are also mostly absent from streams flowing into San Francisco Bay, except for the Napa River and Russian River, where they are rare.
Hardhead Homes
Hardheads like to live in deep pools in small to large rivers. These pools usually have rocky or sandy bottoms. They prefer places that haven't been disturbed much by humans. You can often find them in bigger streams at lower and middle elevations.
They especially like clear, deep pools with sand, gravel, or large rocks, and a slow current. Sometimes they live in reservoirs (man-made lakes), but their numbers there can go up and down quickly. In rivers, they usually stay in the lower half of the water. In slower or still waters like reservoirs, they might swim closer to the surface.
Hardheads are almost always found with Sacramento pikeminnow and often with Sacramento sucker. They usually don't live in waters where non-native fish, especially sunfish, are common.
Hardhead Life and Habits
What Hardheads Eat
Hardheads mostly eat food from the bottom of rivers and streams. They look for small creatures without backbones (invertebrates) and water plants. They also eat insects and algae that float in the water. Sometimes, they might eat tiny organisms called plankton or insects from the water's surface. In Shasta Lake, hardheads have been seen eating tiny crustaceans called cladocerans.
Young hardheads (less than 20 cm long) mainly eat small creatures from the bottom. This includes larvae of mayflies and caddis flies, as well as small snails. Bigger hardheads eat stringy algae, crayfish, and other large invertebrates. As hardheads grow, their teeth change. Young fish have hooked teeth for catching insects, but older fish develop flatter, molar-like teeth that are better for grinding plants and larger invertebrates. They don't seem to eat other fish.
Growth and Life Cycle
Hardheads can grow to about 7-8 cm (3 inches) in their first year. By the end of their second year, they might be 10-12 cm (4-5 inches) long, and by the end of their third year, 16-17 cm (6-7 inches). In some rivers, like the American River, they can reach 30 cm (12 inches) by age four. In other rivers, like the Pit River, it might take them 5 or 6 years to reach that size. Some very old hardheads from the Feather River, aged 9-10 years, were 44-45 cm (17-18 inches) long. It's thought that even bigger and older fish might live in the Sacramento River. Hardheads in smaller streams usually don't grow longer than 28 cm (11 inches).
Hardheads become ready to have babies after their second year. They spawn (lay eggs) in April and May. During this time, adult fish swim upstream into smaller streams. Females have been found with eggs ready to be laid in March. It's believed that spawning times can differ based on the location. In the Central Valley, they might spawn by May-June, but in higher areas, it could be as late as August.
Adult hardheads can travel more than 75 km (47 miles) from large rivers or reservoirs to spawn in smaller streams. Fish living in smaller waters travel shorter distances, usually less than 1 km (0.6 miles), from their home pool to breed. While no one has directly seen hardheads spawning in the wild, it's thought to be similar to their relatives, the Lavinia exilicauda and Sacramento pikeminnow. These fish lay their fertilized eggs in sand or gravel where the water has plenty of oxygen, like in fast-flowing areas or at the upper ends of pools. Hardheads seem to have the most successful breeding when rivers have their highest water flows between April and June.
Female hardheads can produce many eggs, sometimes over 20,000! The number of eggs can range from 7,100 to 23,900. It's thought that the fertilized eggs develop among the gravel. Baby hardheads (larvae and post-larvae) probably prefer the edges of streams where there's lots of plants for cover. As the young fish grow, they move into deeper waters. If the streams they hatched in dry up sometimes, they can be carried downstream by the current. Small young hardheads, about 2-5 cm (1-2 inches) long, might form large groups in shallow calm waters or among rocks near stream banks.
Adult hardheads usually swim in groups in the deepest parts of pools. They cruise around slowly during the day and become more active in the early morning and evening when they feed. In some reservoirs, large adults have been seen near the surface on warm summer days. This makes them easy targets for large fish-eating birds like the Western osprey and the bald eagle.
Protecting Hardheads
Hardheads used to be found everywhere in their natural range. However, their populations have become separated, and they have disappeared from many main rivers. This is because their homes have been changed, making them unsuitable for this special fish. For example, in the Cosumnes River, hardheads are gone, and it's thought that the arrival of redeye bass might be the reason.
Hardheads are mostly absent from reservoirs where water levels change a lot each year. They can survive in small numbers in hydroelectric reservoirs where water levels are more stable. They are also at risk from invasive fish that eat them, especially predatory bass from the Centrarchidae family. Dams and changes to rivers generally don't help hardheads and often help introduced fish species instead.
Hardheads are also sensitive to pollution from farms. Old records from native people's sites in the Sacramento and San Joaquin basins show that hardheads used to be much more common than they are now. Overall, changes to water flow, pollution, and the introduction of non-native fish have caused their numbers to drop. People also used to see them as competition for fish they wanted to catch.
Hardheads seem unable to return to areas where they have disappeared from on their own. To help them, some ideas include putting them back into suitable areas where they used to live. It has also been suggested that managing water flows to benefit hardheads and other native fish, while making it harder for non-native species, should be studied and put into action. Measures to lessen the impact of dams and river channeling are also important.
See also
In Spanish: Mylopharodon conocephalus para niños
