Mottled sculpin facts for kids
Quick facts for kids Mottled sculpin |
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| Conservation status | |
| Scientific classification | |
| Genus: |
Cottus
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| Species: |
bairdii
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| Synonyms | |
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Cottus ictalops |
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The mottled sculpin (Cottus bairdii) is a small freshwater fish. It belongs to the sculpin family, called Cottidae. You can find these fish in many parts of North America, though not everywhere.
As its name suggests, the mottled sculpin has a mix of colors. It has bars, spots, and speckles spread out on its body. Its large fins, called pectoral fins, have stripes. The first fin on its back has thin, soft spines and connects almost to the second back fin. Mottled sculpins can grow up to 15 centimeters (about 6 inches) long.
These fish mainly eat young aquatic insects. They also munch on tiny crustaceans, small fish, fish eggs, and some plants. Other fish, especially trout, like to eat sculpins. Mottled sculpins prefer clear water with lots of oxygen. They often live in rocky areas of mountain streams, springs, or along lake shores.
Mottled sculpins lay their eggs from early winter to late spring. The male fish's head gets darker during this time. He picks a safe spot for a nest, often under a rock or ledge. After a special dance, the female enters the nest. She turns upside down and sticks her eggs to the ceiling of the nest. Usually, several females will lay eggs in one nest. The male then fertilizes the eggs and guards them. He fans the eggs with his fins to keep them clean and healthy.
Mottled sculpins are found in different areas across their range. They are common from the Tennessee River north to Labrador. Separate groups live in the Missouri River, the Columbia River system in southern Canada, and the Bonneville system in the Great Basin.
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About the Mottled Sculpin
Mottled sculpins, known scientifically as Cottus bairdii, are common fish across most of North America. They are only given limited protection in New Mexico. These fish eat many different things, including snails and other small creatures. Their main diet is made up of insects that live at the bottom of the water.
Where They Live
Mottled sculpins like habitats with plenty of small insects to eat. These places are usually fast-moving parts of streams with clear, rocky bottoms. The water speed they prefer is moderate, between 0.20 and 0.38 meters per second.
The mottled sculpin lives in a large area of North America. Their natural home stretches from Northern Canada down to the Mobile and Tennessee River systems. They are also often found in streams in the Rocky Mountains and many streams across the Midwest United States. Their range has stayed mostly the same over the years. This is because they are tough fish and can live in a wide range of temperatures.
However, in some areas, mottled sculpins have disappeared from streams where they used to live. This is because they are very sensitive to harmful levels of metals like cadmium, copper, and zinc. Zinc seems to be the most dangerous metal for them. One study found that mottled sculpins are the third most sensitive water animal to zinc. So, areas with a lot of mining or coal burning can be a big threat to these fish.
What They Eat
Mottled sculpins are known for living in fast-moving water where they mostly eat insects that live on the bottom. One study found that these bottom-dwelling insects make up almost all (99.7%) of a mottled sculpin's diet. The most common types are fly larvae and pupae. The small remaining part of their diet (0.3%) includes snails, tiny clams, water mites, and sometimes even sculpin eggs or other small fish.
This means mottled sculpins are not a big threat to popular game fish. However, they have been known to eat trout eggs. Male sculpins are known to remove their young if they get sick. They also prefer to mate with older, larger females.
Who Eats Them
The main predators of sculpins are different types of game fish. These include brook trout, brown trout, northern pike, and smallmouth bass. Sculpins usually live alongside fish from the Salmonidae family, which includes trout. Their main competitors are other small fish that live on the bottom, especially other sculpin species.
Young and female mottled sculpins are often found among clean rocks in the water. Males, however, are commonly found in areas with algae. These fish prefer cool, clear streams. They can live in warmer streams but do not prefer them as much as some other sculpin species.
Life Cycle and Reproduction
Mottled sculpins become old enough to reproduce at two years of age. Their breeding season is usually in April and May. When the season begins, the males find safe spots under flat rocks, sunken wood, or other debris in stream beds.
To mate, a female will come to the male's nest and lay her eggs there. The female chooses her mate based on his physical traits. Larger males often pick nesting sites with better resources. So, when a female chooses the largest male, she is picking good genes and a good place for her young to grow. After mating, she either leaves or the male chases her away. Males do this to protect the eggs, as females might eat them right after spawning. The males continue to guard the eggs until the young fish have absorbed their yolk sac and are ready to swim on their own.
Mottled sculpins usually mate once a year. A female can lay anywhere from 8 to 148 eggs in one clutch. However, one male can mate with ten or more females in a year. This can lead to very large nests. One study looked at twelve different nests in a year. They found that a single nest could have anywhere from 54 to 1587 eggs, with an average of 744 eggs per nest. Mottled sculpins typically live for about six years.
Protecting Mottled Sculpins
The mottled sculpin is not currently listed as a threatened or endangered species by the government. In New Mexico, it has limited protection. There is no current plan to manage this species because it is very common across North America. It is found in many places because it can live in all sorts of environments.
Even though the species is not threatened, it has received attention in some areas of the Western United States. This is because it has disappeared from some streams that have many trout but no sculpins. This was strange because these two species usually live together in similar places. The problem was that the streams without sculpins had high amounts of zinc. One study showed that mottled sculpins are the third most sensitive species to high levels of zinc.
The U.S. Environmental Protection Agency (EPA) uses trout species to decide how much zinc is safe in water. This means the current safety standards might not be good enough to protect all types of fish. In southeast Minnesota, there are plans to help the sculpin population grow again in streams. These streams once had poor water quality but have since improved. The next step is to release 200 mottled sculpins each year until the population starts to recover in those local streams.
Zinc is not the only metal that threatens mottled sculpin populations. One study found that mottled sculpins were also more sensitive to copper and cadmium than other fish species. The main reasons these three metals get into water are from mining, burning coal, making steel, and melting metals.
