The nearly-new Seikongen, which was built in Hong Kong this year, sank during loading operations near Pilpilehue, not far from the city of Puerto Montt, more than 1,000 kilometres south of the Chilean capital, Santiago.
Unloading work is taking place during a five-hour window from 7am to noon when the tide is lowest.
The wellboat was vented to remove all hazardous gases before work began. After this was done, an opening was made in the hull.
The fishing vessels Doña Marina and Don Pedro are being used to remove the salmon. Chilean Navy shared film of the Doña Marina's arrival at the wellboat.
The wellboat's owner, CPT Empresas Marítimas, which was transporting the salmon for major Chilean salmon farmer Camanchaca, said that during the first day of the operation yesterday "everything worked according to plan. We managed to extract 15 tonnes of fish and 40 tonnes of water".
The company said the first part of yesterday was dedicated to coordination, which meant the time allocated to the extraction operation was reduced. It is expected that the volume of extraction will now increase, since there is no need to perform more logistics work.
Local communities could also breathe a sigh of relief after De la Pride assured them that the dead fish would not be dumped at sea, something that has happened in the past in Chile.
Better condition than expected
De la Pride said during a press conference that the people dealing with the recovery operation were surprised when they finally got access to the hold.
"The best news was that the salmon are in much better condition than expected. Due to the water temperature the decay process been slow, and the salmon remain whole. This confirms a smaller impact than we feared."
The biomass on board will be treated as industrial waste and taken to landfill sites. De la Pride added that it was hoped some of the salmon can be used for fishmeal.
"But it is not yet confirmed if this is possible," added the mayor.
The hull of the Seikongen was not damaged and the causes of the sinking are still unknown.