As for its use in animal feed, the European Commission scientific committee on animal nutrition issued a warning about the pigment and urged the industry to find an alternative. But in response, the British Food Standards Agency took the position that normal consumption of salmon poses no health risk. No government has banned the pigment from animal feed.
Scientists in the U.S. are trying to determine the extent of the contamination in salmon and what levels are safe for human consumption.
The culprit appears to be the salmon feed, which contains higher concentrations of fish oil -- extracted from sardines, anchovies and other ground-up fish -- than wild salmon normally consume. Man-made contaminants, PCBs and dioxins make their way into the ocean and are absorbed by marine life.
The pollutants accumulate in fat that is distilled into the concentrated fish oil, which, in turn, is a prime ingredient of the salmon feed.
Farmed salmon are far fattier than their wild cousins, although they do not contain as much of the beneficial omega-3 fatty acids.
The industry complains that environmental activists have misinterpreted the contaminant studies, needlessly frightening consumers.
"The concern is that people will stop eating fish," said Walling, of the British Columbia Salmon Farmers Assn. "Salmon is a healthy food choice. Our Canadian government says this is a safe food."
Environmentalists in British Columbia and Scotland recently launched campaigns urging consumers to boycott farmed salmon until the industry changes many of its practices.
At the least, they want the farms to switch to solid-walled pens with catch basins to isolate farmed fish -- and their diseases, pests and waste -- from the environment. The ideal solution, they say, is to have the farmed stock raised in landlocked tanks.
Protests notwithstanding, the industry is expected to get a lot bigger. Demand for seafood is rising and will double by 2040, according to the U.N.'s Food and Agriculture Organization. Nearly half the world's wild fisheries are exhausted from overfishing, thus much of the supply will likely come from farmed seafood.
"Aquaculture is here to stay," said Rebecca Goldburg, a biologist who co-authored a report on the industry for the Pew Oceans Commission. "The challenge is to ensure that this young industry grows in a sustainable manner and does not cause serious ecological damage."