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The escape of farmed fish into the wilderness destroys the local ecosystem
In August 2017, a salmon farm in Washington State, USA experienced the ultimate nightmare. Approximately 305,000 fish escaped from a collapsed net pen. Escapes of this magnitude are extremely rare and while an estimated two third of the fish were recovered, the event raised governmental, NGO and public concerns about potential negative environmental and genetic impacts of escapes.
While escapes can occur in the aquaculture production of any species, Atlantic salmon escapes are particularly concerning because the location of farms is typically nearby wild Atlantic or Pacific salmon migration routes. From an environmental perspective, escaped farm-raised salmon may compete with wild salmon for food and habitat. Additionally, there is the concern of potentially spreading disease. Escapes of farm-raised fish such as Atlantic Salmon also raise concerns of cross-breeding between farm and wild fish populations. The genetic term for this is introgression. Because farmed Atlantic salmon are selectively bred to make them more suitable for commercial aquaculture they possess different traits then their wild counterparts. Here the concern is any cross breeding between farmed and wild populations will weaken the resilience of wild salmon.
In addition to governmental regulations which address farm locations, net pen structural requirements and escape reporting, GLOBALG.A.P. standards also address escapes through responsible aquaculture practices such as veterinary health plans to address potential outbreak and spread of disease.