Colorado pikeminnow facts for kids
Quick facts for kids Colorado pikeminnow |
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The Colorado pikeminnow (Ptychocheilus lucius) is the biggest minnow fish in North America. It's also one of the largest minnows in the world! Some reports say these fish used to grow up to 6 feet (1.8 meters) long and weigh over 100 pounds (45 kg).
This fish is native to the Colorado River Basin, which is in the southwestern United States and nearby Mexico. Long ago, it was an important food source for both Native Americans and early European settlers.
The Colorado pikeminnow used to be very common. But its numbers have dropped a lot. It has even disappeared from the Mexican part of its home. In the US, it was listed as an endangered species in 1967. Three other large fish that live only in the Colorado Basin are also endangered: the bonytail chub, humpback chub, and razorback sucker. Today, the IUCN lists the Colorado pikeminnow as a vulnerable species. This means it's at risk of becoming endangered if its situation doesn't improve.
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What Does It Look Like?
Like other fish in the Ptychocheilus group, the Colorado pikeminnow has a long, slender body. It looks a bit like a pike. Its head is shaped like a cone and is a bit flat. The head makes up almost a quarter of the fish's total length.
The fish's color changes from a bright olive green on its back to a lighter yellowish color on its sides. Its belly is white. Young pikeminnows also have a dark spot on their tail fin. Both the fin on its back (dorsal fin) and the fin on its underside (anal fin) usually have 9 rays, which are like the bones that support the fins. Inside its mouth, it has long, hooked teeth called pharyngeal teeth.
Old stories from people interviewed in 1994 said that 6-foot-long fish were once common. These estimates came from looking at old fish skeletons. In the 1960s, fish caught were about 60 cm long when they were 11 years old. But by the early 1990s, the biggest fish caught were only about 34 cm long. Today, scientists think a typical adult pikeminnow weighs between 4 and 9 pounds. It's rare to see one longer than 3 feet now.
How It Lives
Young pikeminnows, when they are very small (up to 5 cm long), eat tiny water creatures. These include cladocerans, copepods, and chironomid larvae. When they grow to about 10 cm long, they start eating insects. As they get bigger, they slowly begin to eat more fish. Once they reach about 30 cm long, they eat almost only other fish.
Young pikeminnows and adult pikeminnows live in different places. Baby fish hatch in fast-moving whitewater canyons. They then float downstream. Young fish mostly live in calm, shallow waters along the edges of the Colorado River system. These areas are often muddy.
Adult fish, however, prefer deeper, more defined river channels. They like to stay in calm spots where the water swirls, called eddies. Here, they hunt for other fish like suckers and minnows.
Colorado pikeminnows are migratory fish. This means they travel long distances in freshwater to lay their eggs. They often return to the areas where they were born. These journeys can be over 100 km long, either upstream or downstream, depending on where the fish usually lives.
Spawning, or egg-laying, happens around the summer solstice (the longest day of the year). This is when river flows start to decrease and water temperatures rise. During breeding season, male fish turn a bronze color and get many small bumps called tubercles on their bodies. Females are usually larger and lighter in color, with fewer tubercles.
When the fish reach their spawning spot, they gather in deep pools and eddies. Then, they swim into nearby fast-moving, shallow areas with rocky bottoms (riffles) to release their sticky eggs. After the eggs hatch, the tiny baby fish are carried downstream by the current for 50 to 100 km.
Where It Lives Now
The Colorado pikeminnow used to live all over the Colorado Basin. This included the states of Arizona, California, Colorado, Nevada, New Mexico, Utah, and Wyoming, as well as parts of Mexico.
However, building dams and changing the river habitats have limited where these fish can live. Now, you can only find them in the upper part of the Colorado River system. They are known to live in the Green, Gunnison, White, San Juan, and Yampa Rivers. Some fish have also been moved to the Salt and Verde Rivers in Arizona, which are within their original home range.
Past Efforts to Reduce Fish Numbers
In the past, some land managers tried to reduce the number of native fish in the Colorado Basin. They wanted to make it easier for people to catch non-native fish for sport. For example, in the mid-1960s, the government used a special chemical called rotenone in the Green and San Juan Rivers. The goal was to create an environment where non-native sport fish could thrive.
In September 1962, the Green River was treated with this chemical. It started upstream of Flaming Gorge. The chemical traveled downstream for three days until it reached the area upstream of Dinosaur National Monument. Another chemical, potassium permanganate, was used to stop the rotenone. But there was more rotenone than expected, and it continued into the Dinosaur National Monument area.
Helping the Fish Recover
People are working hard to help the Colorado pikeminnow recover. Here are some of the main efforts:
- Dam Operations: They are trying to manage dams so that river flows are more natural. This helps create better conditions for the fish.
- Fish Passage: They are improving ways for fish to move up and down the rivers, around dams and other barriers.
- Limiting Non-Native Fish: They are trying to stop or reduce the release of non-native fish into the rivers. This is because non-native fish can compete with or eat the native pikeminnows.
So far, helping the Colorado pikeminnow recover has been a slow process.
See also
In Spanish: Ptychocheilus lucius para niños
