Fish kills on two P.E.I. salmon-spawning rivers have been "catastrophic," says a UPEI scientist.

Mike van den Heuvel, a toxicologist with the Canadian Rivers Institute, says most Islanders are unaware of just how serious the fish kills on western P.E.I.  have been.

"The fish kills are particularly catastrophic. There are 10 first-class salmon spawning rivers left on P.E.I. And two of those rivers have now been hit by fish kills."

'There's never been any serious prosecution of these events.' —Toxicologist Mike van den Heuvel

Pesticides are almost always to blame for massive fish kills, he said. They wash from farm fields into rivers during heavy rains.

The province has a mandatory buffer zone between fields and rivers of 15 metres. But to stop fish kills, van den Heuvel said, that zone needs to be bigger and government has to get tougher about enforcement.

"There's never been any serious prosecution of these events. Oilsands companies killed 1,600 ducks and had to pay $3 million, [but] nobody has ever had to pay anything for the millions of fish that have died on P.E.I."

Environment Minister Richard Brown said he's taking the situation seriously, and depending on results of the investigation, he would consider making the laws tougher.

"Maybe our current buffer zone legislation, which is 15 metres, may have to be changed a bit to accommodate areas of high risk."

Green Party Leader Sharon Labchuk said that remedy alone is short-sighted.

"There's a bigger problem here. These chemicals that are killing the fish in the streams, we're inhaling those," said Labchuk. "They're going into our lungs, we're breathing this stuff."

Labchuk wants the province to ban pesticides and move toward all organic farming. Brown said he won't consider that.

"Well, if we ban chemicals, then we ban agriculture on P.E.I. Chemicals are a cost of doing business."

Brown said investigators are doing aerial surveys of the land near the fish kills. And he said if buffer zone violations are discovered, charges will be laid.