California scientists debate whether it’s menace or messiah – Times-Herald

Government officials to prevent deadly illness often praise low mosquitofish as a savior of public health. However, some environmentalists call it a “pesto minnow” and a “fish destroyer.”

Almost a century after the finger-sized fish was first introduced to California in Sacramento’s lily pond, it is arguably the most ubiquitous freshwater fish in the world. However, mosquitofish are also one of the most invasive species in the world.

Almost all mosquito and carrier extermination districts in California are now deploying creatures with a variety of strategies, balancing pest control capabilities with ecological destruction of fish.

Despite the deaths of 74 people from the mosquito-borne West Nile virus in California over the last five years, greedy fish are of great help in combating infectious diseases. But in the wild, it also threatens local biodiversity — defeating native species and permeating seemingly every corner of the Golden State.

“Every crazy ass place in California seems to have something to do with mosquitofish,” said Eric Parcobucks, a professor of ecology and evolutionary biology at the University of California, Santa Cruz.

When first identified in the 1850s, mosquitofish were native to the southeastern United States, but moved to California in April 1922 and were adopted by the World Health Organization and various military forces as a replacement for the toxic pesticide DDT. After being done, it spread. All over the world.

“People put non-native fish everywhere,” said Palkovacs. “They didn’t have two thoughts about the food web and its impact on the natural environment.”

According to experts, the problem is that fish do not distinguish between light meals in rice-sized offspring of diseased mosquitoes and endangered marine life.

Chad Mitcham, a senior biologist at the Ventura office of the US Fish and Wildlife Service, saw the impact first hand. A few years ago, he sampled thousands of endangered federal government endangered Santa Cruz long-toed salamander larvae in a pond in northern Monterey County. A few months later, after the mosquitofish were introduced into the pond, only 10 larvae remained.

“I was very disappointed to see it,” Mitcham said.

Fish also contribute to the outbreak of algae, a vast green sheet of microorganisms that block sunlight and oxygen from other species. When mosquitofish feed on zooplankton, it usually suppresses algae, an uncontrolled population of algae explodes and covers the pond.

The fact that mosquitofish can live almost anywhere, from frigid seas to geothermal springs, and from coffee to bleach, has promoted global dominance of fish.

However, mosquitofish play an important role for public health agencies around the world. In 2010, the city of Sochi, Russia, built a bronze mosquitofish statue to commemorate the fish’s contribution to the fight against malaria.

In California, most vector management districts send mosquitofish to infected waters such as untreated pools.

Tired of maintaining a chlorinated pool in her home on the mountain above Sokel, Deborah Beer decided a few years ago to replace it with a natural pond to grow local wildlife. ..

“Sure enough, we brought a great explosion to the tree frog population and dragonflies,” she said. “But the number of mosquitoes has increased.”

So Beer contacted Santa Cruz County Mosquitoes and Vector Control and dumped a small bag of mosquitofish in a new pond. Thousands of fish today protect beer dwellings from annoying bites and dangerous viruses such as West Nile fever and St. Louis encephalitis.

“They certainly really improved the quality of life in real estate,” she said. “It’s absolutely impressive.”

Amanda Paulsen, Vector Control Manager in Santa Cruz County, said mosquitofish were particularly helpful after dozens of pools were abandoned due to forced evacuation after a wildfire last year.

However, her agency is paying attention to its usage. Mosquitofish are collected only from natural waterways and pre-stocked pools and delivered only to self-contained waters. We also distribute leaflets to encourage users not to let the fish go wild.

However, vector control agency strategies vary widely between counties in California. Three small tubs in Santa Cruz County are home to hundreds of mosquitofish throughout the year, but Sacramento and Yolo County vector management agencies have found millions of mosquitofish in ponds on 22 grounds each year. I am breeding. In 2020 alone, more than 2 million mosquitofish were released.

Our business at Elk Grove is one of the largest in the world. Reason: Sacramento-Yoro district is responsible for handling the mosquito threat in more than 13,000 acres of paddy fields. Here, we are creating fertile insect breeding grounds near residential areas that are densely populated with shallow waters.

“If these rice fields are not treated with fish and pesticides, there is a great risk to the population,” said Tony Hedley, the district’s fisheries supervisor. “It’s heavier than where these fish end up.”

However, prioritizing human health often puts other species at risk.

“Obviously, if any flood occurs, these mosquitofish will go elsewhere,” Hedley said. “Honestly, I don’t know the full impact of mosquitofish, but I’m more worried than ever.”

California law allows public health agencies in most counties to plant mosquitofish without permission, even on private land. Both the Santa Cruz County and Sacramento-Yoro agencies state that the owner’s consent is usually required before distributing the fish, but whether private citizens have used or disposed of the fish properly. I admit that there is no way to track it.

Therefore, authorities are continually working to balance public health commitments with the ecological threat of fish.

“The mosquitofish itself is neither good nor evil,” said Palkovacs. “We should cast them so that they are neither the protagonist nor the villain of the story.”

California scientists debate whether it’s menace or messiah – Times-Herald Source link California scientists debate whether it’s menace or messiah – Times-Herald

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