Search All of the Math Forum:
Views expressed in these public forums are not endorsed by
NCTM or The Math Forum.



How many Piranhas are swimming in US rivers?
Posted:
Aug 30, 1996 7:12 PM


Natural History Magazine of August 96, contains the article, "Jaws: Something's fishy in the Cornbelt", by Roger L. Welsch. The article discusses, in a nontechnical and lighthearted way, the question: if 4 or 5 piranhas were caught by fishermen last year, how many others are there? And should people dangle their toes in midwestern rivers?
Here's a sample of the prose: "So what percentage of the piranhas would you guess that fishermen did catch? We are talking about a lot of water, remember, and a handful of fishermen. Half? Even that is preposterous. A quarter? A tenth? A hundredth? "Let me put it another way. If I turned loose a hundred tagged fish in all the public waters in the area [Nebraska and Iowa] and set out to catch one of them with a wad of stink bait on a hook and line, what do you suppose my chances would be? You could offer me ten million dollars and I wouldn't even try. What would be the use? A hook and line is that small, a fisherman is that puny. I think you could turn loose a thousand tagged fish, maybe ten thousand, and the chances of one of them ever being caught or seen again would be infinitesmial. All of which is to say, there must be a lot of piranhas out here if folks are catching a couple a month." _______________________________ William J. (Sandy) Wagner 127 O'Connor St., Menlo Park, CA 94025 (415)3288657 (voice) (415)3231035 (fax) sandyw@best.com



