A goldfish (Carassius auratus auratus) weighing 4.2 pounds and nearly 1.5 feet long has been found in Lake Tahoe (video). Environmentalists fear that their presence may have a detrimental impact on the ecosystem of Tahoe, a large fresh water lake in Sierra Nevada.
The goldfish is a freshwater fish and was among the earliest to be domesticated, and is one of the most commonly kept aquarium fishes.
It was first domesticated in China more than a thousand years ago, and several distinct breeds have since been developed. Goldfish breeds vary greatly in size, body shape, fin configuration and colour––various combinations of white, yellow, orange, red, brown, and black are known.
It was only recently that researchers searching the Lake for invasive fish species scooped up a goldfish.
One of those was trawling was environmental scientist Sudeep Chandra of the University of Nevada, Reno. He was quoted in LiveScience as saying: “During these surveys, we’ve found a nice corner where there’s about 15 other goldfish.”
“It’s an indication that they were schooling and spawning,” he said.
Environmentalists are worried over the arrival of the fish. They think that they were probably dumped there by aquarium owners. Goldfish are an invasive species that could interfere with Lake Tahoe’s ecosystem.
Chandra said that it is not clear whether the giant fish were introduced as fully grown adults, or while they were still small. But even a small creature can have a big impact, if there are enough of them.
The goldfish are just one of several species of invasive warm-water fishes in Lake Tahoe. “The invasion is resulting in the consumption of native species”. What is more, the invasive fish excrete nutrients that cause algal blooms, which threaten to muddy Lake Tahoe’s clear waters.
In the United States and elsewhere aquarium dumping has become a common practice, and it is taking a heavy toll on native wildlife.
A report on California’s aquarium trade found that fish owners and importers are introducing hardy, non-native aquatic species to California waters. “Globally, the aquarium trade has contributed a third of the world’s worst aquatic and invasive species,” Williams, who was lead author of the report, was quoted in OurAmazingPlanet.
While the exact number of aquarium owners dumping fish is not known, scientists know the practice is occurring because these species could not have ended up in these waters naturally.
According to Williams more than 11 million non-native marine organisms representing at least 102 species arrive at ports in San Francisco and Los Angeles alone. They include tropical fish, seaweed and snails. One of the nastiest is a deadly type of seaweed known as Caulerpa, a type of algae that produces toxic compounds that kill off fish.