Fish raised in aquaculture production can cause serious harm when unintentionally or intentionally released from aquaculture facilities. Escaped fish can harm wild fish populations, other species and the ecosystem.
Fish in open net pens escape in small numbers even during normal operations, and can escape in large quantities when nets are damaged by storms or predators, such as sharks and sea lions.
Atlantic salmon escapes on the U.S. and Canadian West Coasts are common; there were 350,000 known escapes in 1997 and farmed Atlantic salmon have been found thousands of miles away from the closest salmon aquaculture facilities.
In the Pacific Ocean, escaped non-native Atlantic salmon have already been found breeding near aquaculture operations in both British Columbia and South America. Escapes are a significant concern because they occur on a regular basis. Escaped fish potentially travel great distances and are a threat to the long-term health and fitness of native populations.
In early 2009, Oceana publicized a massive escape that took place on December 31, 2008. We revealed that the escape involved about 750,000 salmon and trout and that some of the escaped salmon were infected with the ISA virus.
Moreover, reports of salmon escapes in Chile range upwards of 10 million a year. The escape of farmed salmon from their cages is one of the most serious environmental problems resulting from open-water aquaculture operations.
Escaped salmon generate various ecological effects including predation and competition with native species, hybridization and transmission of diseases to native wild fish. Also, many of the native species affected by escaped salmon are the target species for artisanal fishing, causing economic losses in this sector estimated at $5 million annually.
Currently, regulation of salmon escape in Chile is very weak. Essentially the only requirement is that farming companies prepare a contingency plan. This has proved to be ineffective in mitigating and even in reporting of escapes. Some companies have insured themselves against escapes which some people believe have led the companies to seek reimbursement (when market prices are down) by negligently permitting massive escapes.