Golden algae spray
As a Game and Fish officer Tom McMahon looks on, City of Phoenix employee Gary Kudas sprays an urban lake to control golden algae, an invasive species that kills fish.

When sport fish started dying off two years ago, a water dweller known as golden alga was the prime suspect.
But the invasive non-native plant could not be pinned down as the cause, at first, said Larry Riley, chief of fisheries for the Arizona Game and Fish Department.
“It’s so small it can be kind of difficult to find,” he said.
Signs of golden algae appeared with the die-off of shad and bigmouth bass in a handful of urban lakes, as well as three lakes on the Salt River: Apache, Canyon and Saguaro. Anglers reported sick and dead fish to Game and Fish officials.
Golden-algae toxin attacks the gills.
“The toxin damages the cells on the surface of the gill,” Mr. Riley said. “It causes the blood vessels and the blood cells to rupture.”
The fish can’t get oxygen and they suffocate.
Though it looked like the work of golden algae, early tests didn’t pick it up. Then samples were collected more carefully, and the technician turned up the magnification on the microscope.
“That’s when he found it was golden algae,” he said.
Northern Europe first reported fish die-offs from golden algae early in the 20th century, Mr. Riley said. It made its way across the Atlantic, reaching west Texas about 20 years ago. It entered Arizona by 2004, though exactly how remains a matter of speculation.
One possible pathway, Mr. Riley says, would be “as a hitchhiker on a boat or fishing gear.”
Even if the algae are dried out, the plant can spring into action once back in the water.
Economic impact
Game and Fish has a direct stake in controlling golden algae. The plant toxin attacks the very sport fish for which the agency sells licenses. Urban lakes in Gilbert and Phoenix have been treated chemically. The cities are picking up the cost, he added.
It might not be practical to treat the larger lakes on the Salt River, though that hasn’t been ruled out entirely, Mr. Riley said.
If the fish aren’t biting, though, it could discourage anglers. That doesn’t just affect the sale of fishing licenses, Mr. Riley says. Like many invasive species, golden algae can have a wide economic impact.
“There are folks with businesses that revolve around the outdoors,” he said. They range from tackle and bait shops to boating suppliers.
But, Mr. Riley said, while overall fish numbers are down in the three big lakes, they’re up from 2004 and 2005.
“There are fish there to be caught,” he said.