SciSun: All that Glitters is not Gold   Leave a comment

Lake Tahoe, on the northern border of California and Nevada, is a beautiful alpine lake with crystal-clear water. At an elevation of over 6,000 feet, for thousands of years the deeper parts of the lake have been a consistent 39 degrees – perfect living conditions for the native Lahontan trout (Oncorhynchus clarki henshawi) that make the lake their home. But there are other things living in the lake too….invasive, warmer-water species like the Bluegill; the Bullhead Catfish; and the Black Crappie (no, we didn’t make that one up). These non-native fish have escaped into the lake – or rather, been let lose into the lake – by fishermen who empty their unused bait into the water; by people who thought it would be ‘nice’ if the lake had more, and different types of fish; and by well-wishers who dump unwanted aquarium fish into the natural environment. For most fish, the almost-but-not-quite-freezing mountain water would be too much, and they would quickly die. But the lake is slowly warming, scientists believe due to changing global climate, and these un-wanted intruders are finding it rather comfortable in this lake habitat, and harming native species in the process.

What harm can a few fish do, you ask? Well by themselves, not that much. But there’s never just a few fish – where there’s a few, soon there will be more and more and some will be bigger and BIGGER, until they are giant monsters that rise out of the lake and take over the government. Well maybe that’s exaggerating, but decide for yourself: Recently scientists have found giant Goldfish (Carassius auratus) in Lake Tahoe that are about 15 inches long. These are not strange mutant fish, at one time they were cute little two-inch pets. Goldfish have the ability to continue growing, to make best use of their environment, long after other animals have reached their maximum size. So foot-long goldfish, or almost TWO-feet long goldfish, have been reported by fish owners over the years. Of course all this growing needs more food – and one of the favorite foods of these out-of-control goldfish are little baby trout, and the even smaller minnows the trout have eaten for generations. Also, bigger goldfish produce more waste, which is lowering the water quality for everyone.

You may have seen photos of really GIANT goldfish that people always seem to find in South America or Asia – fish that are five and six feet long. These are not actually goldfish, but Carp, a different species, but closely related to Goldie. So the Lake Tahoe goldfish aren’t going to grow that big, their maximum size seems to be less than two feet. At least that’s what everyone hopes.

Giant goldfish kaempe_guldfisk WIKI

‘One of the largest Goldfish you’ll find on the ‘net. Or, IN your net.’

Scientists aren’t certain how many of these lake giants there are, but for now they seem to be only in one part of the lake and the researchers are trying to capture them. Already they’ve caught about 90 goldfish – but over 35,000 other invasive fish, which are spreading throughout the lake. This is in addition to non-native snails and plants and other aquatic species that just happen to ‘find their way’ into Lake Tahoe, and other fresh water lakes throughout North America. When the Tahoe fish are caught, they’re inspected and donated to nearby food agencies. Lately we’ve noticed more and more ‘Chef’s Special’ fish dishes on local menus. Just sayin’.

http://tahoe.ca.gov/

http://www.fws.gov/fieldnotes/regmap.cfm?arskey=31931

^^^

Michonne Says: Those goldy-fish sound like they’re almost as big as a marmot. It’s good they don’t come out of the water. Or that marmots need to go into the water. That’s for raccoons and bears.

Posted March 3, 2013 by ECOVIA eco-adventure® in SciSun

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