The hole, which measured about 15cm x 50cm and was at a depth of 20 metres, was discovered by divers on Tuesday morning and repaired.
The Icelandic Food and Veterinary Authority (MAST) was informed by Arnarlax on Tuesday.
There were 157,000 salmon in the pen, with an average weight of 1.3 kilograms. Arnarlax chairman Kjartan Ólafsson said feeding indicated no changes in biomass and no fish had been seen outside cages or caught in the nets put out.
“We follow strict rules on reporting incidents like this to authorities and we will now await a final report and outcome of that process,” he added.
Guðni Magnús Eiríksson, head of the salmon and trout division at the Directorate of Fisheries told broadcaster RÚV that the Directorate was notified of the matter at noon on Tuesday, and Arnalax had already engaged its contingency plan. “The plan entails that nets are placed around the pen which the tear was discovered on. What we did was to send inspectors to the site immediately, who confirmed that the plan has been engaged, and inspect conditions wholly,” Guðni stated.
“According to Arnarlax’s description, the tear is not really large, but still large enough that they cannot rule out that fish escaped. There are no indications right now that this is a major incident, but it is not wholly clear.”
The incident comes at a sensitive time for Arnarlax, which has just won a court case brought by the owners of salmon fishing rights in the river Haffjarðará.
Reykjavik District Court dismissed the claims of rights owners Akurholt and Geiteyri against Arnarlax, MAST and the Environment Agency of Iceland.
The fishing rights owners had demanded that the salmon farming licences of Arnarlax in Arnarfjörður should be annulled because the operation could be harmful to their business.
Lawyer Kristín Edwald, representing Arnarlax, said: “In essence, the District Court held that the owners of the salmon fishing rights had not suffered any loss due to Arnarlax’s operations and that they had not proved that the operation would specifically harm their interests. Thus, they did not have any particular legitimate interest in pursuing their lawsuit, which is grounds for dismissal under Icelandic procedural law.”