Invasive Aquarium Fish
Home tropical fish aquariums are home to a number of pretty fish and seaweeds. Perfectly harmless right? Not in the wrong environment. It is surprising how hardy some of them can be if let loose in the wild. In a report released today to the California Ocean Protection Council, lead author Susan Williams, an evolution and ecology professor with the UC Davis Bodega Marine Laboratory, found that more than 11 million non-native ornamental marine individuals — such as tropical fish, seaweed and snails bound for aquariums — representing at least 102 species are being imported annually through California’s ports of San Francisco and Los Angeles, primarily from Indonesia and the Philippines. And 13 of those species have been introduced to California marine waters — presumably after being released from aquariums.
While that number seems low, the report cautions that 69 percent of the introduced species established themselves successfully in California, signaling a potential threat to marine ecosystems. Some non-native, invasive species can rapidly spread and out compete native species for food and habitat.
"Although relatively few aquarium species have been introduced compared to species in other pathways, such as ballast water, they are highly successful because they’re grown to be hardy and robust," Williams said. "They have to be tough to survive in the trade."
The aquarium trade represents a $1 billion a year global industry and a popular home hobby, second only to photography, the report said. It has also introduced some of the world’s worst invasive species, such as the seaweed Caulerpa, the killer algae that infected two lagoons in Southern California in 2000 and cost California more than $6 million to eradicate. Caulerpa taxifolia is a species of seaweed, an alga of the genus Caulerpa. Native to the Indian Ocean, it has been widely used ornamentally in aquariums.
Another invader is the highly predatory lionfish, which regularly enters the state’s ports through the aquarium trade — 20 lionfish were imported into San Francisco International Airport on a single day, the report said.
Introduced to Florida in 1999, it spread rapidly throughout the Caribbean Sea and along the East Coast by 2010. Lionfish have not been reported in California waters, but the fish is able to withstand cooler temperatures. If released, a lionfish could establish itself as far north as San Francisco Bay and, even farther, as oceans continue to warm, the report said.
Lionfish have successfully pioneered the coastal waters of the Atlantic in less than a decade and pose a major threat to reef ecological systems in these areas. A study published in 2006 comparing their abundance from Florida to North Carolina with several species of groupers found that they were second only to the native scamp grouper and equally abundant to the graysby, gag, and rock hind. Although the lionfish has not expanded to a population size that is currently causing major ecological problems, their invasion in the United States coastal waters could lead to serious problems in the future. One likely ecological impact caused by Pterois could be their impact on prey population numbers by directly affecting food web relationships. Studies show that lionfish could be decreasing Atlantic reef diversity by up to 80%. In July 2011, lionfish were reported for the first time in the Flower Garden Banks National Marine Sanctuary off the coast of Louisiana.
While the report highlighted lionfish and Caulerpa as species of special concern, it identified at least 34 other species deemed able to tolerate California’s current marine climate.
The report is one of six that the UC Davis Bodega Marine Laboratory coordinated for the state, each exploring a different vector, or pathway, through which invasive species can enter California ocean waters. The other pathways include aquaculture, live seafood, live bait, fishing vessels and recreation vessels. Williams said it makes sense to focus on invasive threats from the aquarium trade because they can be managed primarily through public education, with minimal regulatory action or expensive measures.
"Aquarium hobbyists can follow some simple practices — like Don’t dump your aquarium — to avoid releasing aquarium species into natural water where they can become an expensive and harmful pest." Williams said that people who no longer want an aquarium species can contact the vendor from which the species came or the California Department of Fish and Wildlife (formerly called California Department of Fish and Game) to learn how to dispose of or return it responsibly.
"From the hobbyist or industry side, it is really hard to figure out the rules and regulations for holding live organisms in the state — for importing, possessing and trading them," said Williams. "So one of our conclusions is that a more centralized information and permitting system would benefit the regulators, industry and hobbyists, and enable scientists to collect more information and better assess the risk."
For further information see Aquarium.
Lionfish image via Wikipedia.