Weak Pesticide Cocktail In Rivers Enough To Blunt Salmon, Steelhead Sense Of Smell - New Scientist

[hatrack]

A weak mix of pesticides in river water dampens a salmon's sense of smell, say researchers. In experiments, Steelhead rainbow trout exposed to low levels of 10 common agricultural pesticides could not perceive changes in levels of a predator's scent.

"You can imagine if a fish is unable to detect just how close it is to a bear, it's a problem," says Keith Tierney, a toxicologist who led the study while at Simon Fraser University in Burnaby, British Columbia.

A depressed sense of smell might also keep fish from finding mates and food. Trout are closely related to salmon, and, though the theory is unproven, pesticides may be a cause of plummeting salmon stocks in Canada and the US, Tierney says.

Fisheries researchers have long suspected that pesticides can deaden fishes' olfactory sense. But most of the evidence was based on fish exposed to artificially high levels of a single chemical and for a short period. In the wild, however, salmon swim through waters polluted with low levels of pesticides and other chemicals that can change from day to day, depending on the amount and nature of the runoff entering the river system.

EDIT

http://environment.newscientist.com/article/dn14091-pesticides-blamed-for-plummeting-salmon-stocks-.html

[robinlynne]

1. I'm so disgusted with my species, the humans.

[tom_paine]

2. Yes, we have mucked it up quite a bit, haven't we?

I share your feelings. We are a shortsighted bunch of primates, aren't we?

(he says as he's burning a few bbls. of oil keeping things a comfortable 75 degrees with the A/C; there's no escaping it)