SciSun: Shell Shocked   Leave a comment

On the border of Northern California and Northern Nevada, in the area known as the Sierra Nevada, you can find Lake Tahoe. The largest freshwater, alpine lake in North America, it’s also among the largest lakes in the world. At more than 1,600 feet it’s the second-deepest lake in the US, and some say it has the best water clarity of any lake: On most days the water is clear to a depth of about 70 feet – so clear the fish and rocks and even old shipwrecks can be seen from above. But in the 1960’s, when scientists first began taking measurements, you could see 100 feet into the water, and there are stories from a hundred years ago of explorers looking so deeply into the lake, they thought it had no bottom.

So what’s muddying the waters? Some of the problem is with construction, logging and mining in the area that create loose soil that’s washed into the lake by wind, rain and snow. The nutrient level has also risen in the water, meaning there’s a higher concentration of materials that other species can use for food, and this had lead to unusually high growth of algae – a small water plant – that’s clouding the water. But what might be one of the most harmful developments is the introduction of the Signal Crayfish (Pacifastacus leniusculus), an invasive, non-native animal that has few predators in the lake and is happy to be at the all-you-can-eat algae buffet.

The Crayfish is a type of crustacean – animal with an exterior shell, many pairs of legs and often living in aquatic environments – that looks amazingly like a miniature lobster. There are hundreds of different types of crayfish living all over the world, and Signal is native to parts of the Western US and Canada, but not Lake Tahoe. It’s believed the species was introduced into the lake about a hundred years ago – although no one knows why this was thought to be a good idea at the time. (The species has also found it’s way to most of Europe; parts of the Mediterranean; Japan; and the United Kingdom. These guys know how to travel!). Since the introduction to Lake Tahoe they’ve thrived and today it’s estimated there are over 300 million of the little lobster-ettes living in the water. Most crayfish eat small water plants or animals, and while it’s true the Signal Cray is helping, somewhat, to control the algae population, the waste created by over 300 million of anything can’t be helping improve water quality.

The crayfish problem has been concerning people for a long time, but no one had any good ideas of what to do. Then, last moth, a local businessman was given permission to do something that hasn’t been done at Lake Tahoe for over 70 years: Commercial fishing that will put the little crustaceans on the menus of local restaurants. This might be unusual in the Sierra Nevada, but in parts of the world eating crayfish is an everyday meal. In the Southern US (where it’s sometimes called crawfish), the mini-lobsters are served as appetizers; deep fried; in sandwiches; in salads; in stew; in soup; as kabobs; pepper crawfish; lemon crawfish; crawfish stuffing; and crawfish any-way-you-can-think.

crayfish USFWS

‘Crayfish’ is so yesterday. Today, we shall be called ‘Langostino’!

 

Right now only Nevada is allowing crayfish fishing, so if any of the little guys are really smart they will scurry to the side of the Lake that’s managed by California, where lawmakers are deciding if they will allow crayfish capture. But at over 300 million of just this one type of crayfish, there should be enough to catch on any side of the Lake for quite some time. And while there are types of crayfish in almost every state, the greatest diversity is not in California or anywhere in the West but in Tennessee where there are 78 different species. And less than one percent of those are in Nashville trying to become country singing stars.

Snap up more information!:

http://www.cabnr.unr.edu/nres/news_story.aspx?StoryID=791

http://linnet.geog.ubc.ca/efauna/Atlas/Atlas.aspx?sciname=Pacifastacus leniusculus

http://tahoe.usgs.gov/facts.html

Posted August 19, 2012 by ECOVIA eco-adventure® in SciSun

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