By ALEXEI BARRIONUEVO


SANTIAGO, Chile - When a devastating virus swept through Chile’s farmed salmon stocks last year, some of the industry’s biggest players laid off thousands of workers, packed up operations and moved to unspoiled waters farther south along the Chilean coast. But the virus went with them.

In January, the Chilean government began drafting tougher measures to improve the sanitary and environmental conditions of the troubled industry. But producers expect deeper losses in the $2 billion industry this year, as the virus continues to kill millions of fish slated for export to the United States and other countries.

Government and industry officials say they have already taken important steps to improve the ways salmon are farmed. But the persistent problems, critics say, reveal that neither the industry nor the government has fully grasped the need for the far-reaching changes required to protect not only consumers and the environment, but also one of Chile’s most important industries from itself.

In the midst of the virus crisis, Chile has continued to raise salmon for export with chemicals and medications not approved for use in the United States and Europe, according to documents from regulators.

While the United States Food and Drug Administration says Chile made some progress in tackling its problems, it will keep Chilean imports of farmed fish under special scrutiny.

Chilean government officials and industry officials say the troubles are part of the growing pains of an industry that in less than two decades built itself into the world’s second largest exporter and the biggest supplier of salmon to the United States.

The virus afflicting the fish, infectious salmon anemia, or ISA, is not harmful to humans, they note. But after The New York Times reported on Chile’s dying farmed fish last year, some buyers, like the supermarket giant Safeway, restricted imports from Chile.

The troubles spurred the Chilean government to step up its controls. Last year Sernapesca, Chile’s national fishing service, tripled its inspections of farmed fish, said Felix Inostroza, the agency’s director.

The measures being weighed by the Chilean Congress, which are expected to be passed before April, would thin the density of salmon pens, where overcrowding has contributed to the virus’s spread, and reduce the use of antibiotics.

The authorities also plan to organize aquaculture permits into “neighborhoods,”where salmon companies will be required to build in rest periods between production cycles, to give the marine environment time to recover, said Rodrigo Infante, general manager of SalmonChile, the industry association.

“It is not enough for the industry to voluntarily police itself,”said Andrea Kavanagh, manager of the Salmon Aquaculture Reform Campaign for the Pew Environment Group in Washington.

“For too long, the government has ceded to industry convenience,” she added,“permitting chemicals known to harm its environment as well as consumers.”

In November, the government a nnounced that it would provide $120 million in loan guarantees to help producers meet the new regulations quickly. But this year, producers still expect salmon output to drop by about 30 percent, said Cesar Barros, president of SalmonChile.