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Don't Dump that Fish

All the world's a fishbowl for an aquarium fish set free. As anyone whose pet fish has defied the odds can attest, aquarium fish are bred to be hardy survivors. Unfortunately, this trait makes it easier for the onetime pets to thrive in an unfamiliar place if their well-meaning owners decide to turn them loose. As an example, gargantuan goldfish pulled from the depths of Lake Tahoe captured public fascination earlier this year. Goldfish (Carassius auratus) are now found in most of California's freshwater habitats, largely as a result of pet releases. Freed from the cramped confines of a fishbowl, goldfish may grow to well over a foot (40 cm) in length in the wild (McGinnis 2006). We at FISHBIO have netted a few massive specimens, like the one shown above, during a survey of Alameda Lake in Santa Clara County.


Although bright and unusual additions to the fish community, goldfish fortunately have not exerted significant damage on native species or habitats compared to other introduced fishes (McGinnis 2006). However, some ornamental species with voracious appetites have a dangerous potential to invade and alter new environments. Researchers at UC Davis released a report earlier this year that found 9 ornamental marine species have successfully colonized California waters. The list includes snails, worms, and crustaceans, but no fish as yet. However, with as many as 179 marine species passing through San Francisco in a single day for the aquarium trade, researchers are on alert for the escape of highly invasive fish species, such as the lion fish that has infested Caribbean waters largely unchecked. The phenomenon is a global problem: introduced ornamental fishes now swim through waters around the world, including the Mekong River (see The Mekong's Amazon exotics).


The aquarium trade is just one route for non-native fish to enter California's waterways. Introduced species already dominate California's freshwater habitats (see graph below), and the majority were intentionally stocked by the California Department of Fish and Wildlife, formerly the Department of Fish and Game (Dill and Cordone 1996). An eight-year survey of the Sacramento-San Joaquin Delta yielded only 8 native species, and each was less than 0.5% of the total catch (Feyrer and Healy 2003). Other potential entry paths for introduced species include aquaculture, live seafood, and live bait species. While aquarium releases are far from the biggest threat to California's native fishes, they are one more source of stress on highly altered ecosystems. So however much your fish looks like it longs for open water, do native fishes a favor and keep it in the tank.

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A small obstacle 

Standing just 24 feet tall, Daguerre Point Dam on the Yuba River is a dwarf compared to most mainstem dams on California's Central Valley rivers, which tower more than 500 or 600 feet. Though short in stature, the dam has become a sizable point of contention. Built at the beginning of the 20th century to prevent mining debris from washing into the Feather and Sacramento rivers, the dam provides hydraulic head for irrigation diversions. Two fish ladders, one on each side of the river, were added in 1937 to allow salmon and steelhead access to the reaches between Daguerre and the Englebright dam upstream.


However, these fish passage facilities prove inadequate under certain flow conditions, and the National Marine Fisheries Service identified the dam as a major stressor to native anadromous fish populations in a biological opinion issued last year. Motivated by the aspiration of healthy salmon populations, various entities now advocate removing the structure, while others maintain the barrier serves as an important water diversion to the valuable local agricultural industry, and also blocks predatory fish (such as striped bass) from accessing salmonid rearing habitat above the dam.


A proposed hydropower project at this site recently stirred up new controversy over the future of the structure. Some see the dam as an outdated remnant... Read more>  

IN THE NEWS: Recent stories you might have missed...
Alaska's Bristol Bay wild salmon fishery valued at $1.5 billion
Alaska Dispatch 

Alaska's Bristol Bay is the most lucrative wild salmon fishery in the world, worth an estimated $1.5 billion according to a new study released by the University of Alaska Anchorage's Institute for Social and Economic Research. The $1.5 billion takes into account the harvesting, processing and retailing of Bristol Bay salmon, as well as the total economic effects of those activities -- all the way from the gill netter who hauls the fish into their boats.... Read more> 

Largest dam removal in California history gets approval

ABC News   

Monterey County supervisors gave their OK for the largest dam removal project in state history. The San Clemente Dam is eighteen miles from the coast in the Carmel Valley. The 90-year-old, 106-foot-tall dam was once a major source of water on the Monterey Peninsula. But it has reached the end of its useful life."The dam was deemed to be seismically unsafe in 1995," said California American Water spokesperson Catherine Bowie. She added that, "as the water provider we had to do something to resolve that safety issue..." Read more>  

Elwha River: Recovery proceeds despite sediment setbacks
Oregon Public Broadcasting

One of the two dams on the Elwha River has been completely removed and there are about 50 feet of the remaining Glines Canyon dam left. Already so much sediment has been released that its clogged up and shut down one of the water treatment plants in nearby Port Angeles, temporarily halting the largest dam removal project in U.S. history. While sediment is a problem for infrastructure people rely on, it's providing excellent new habitat for fish and wildlife in the Elwha watershed on Washington's Olympic Peninsula... Read more 

3 million hatchery salmon released into American River in Sacramento
The Sacramento Bee 

State Department of Fish and Wildlife officials on Monday and Tuesday released 3 million juvenile salmon at the mouth of the American River in Sacramento.The fall-run chinook salmon, produced at the Nimbus Hatchery, have historically been transported in trucks to San Francisco Bay to help the fish avoid predators. But research showed few found their way back to the river. So in 2010, hatchery officials began releasing a major share... Read more >  

New deep-sea fish species found in Antarctica

To catch Antarctic toothfish, you must bait your hook with Peruvian squid and cast it into the depths of the Ross Sea. This is what a team of Ukrainians did on a fishing trip near Antarctica. But sometimes, Mother Nature trips you up. Sometimes, you catch a hopbeard plunderfish. In 2009-2010, Ukrainian mariners happened to pull up three fish that looked unfamiliar. Further analysis found that they were a previously undiscovered species, dubbed the hopbeard plunderfish... Read more >