Chile’s National Fisheries and Aquaculture Service, Sernapesca, has found that a total 12 percent or 103,720 salmon escaped from farmer Blumar’s Caicura grow-out center resulting from cages sunk in heavy storms, reported on 27 June.
A total 875,125 salmonids in the fattening stage – at an average weight of 3.8 kilos – were registered in 18 cages at the center, two of which saw escapes and the other 16 sinking to the seabed. Blumar performed prospecting studies and analysis of images taken with two underwater robots (ROVs), and with high-tech Hammerhead sonars, and believes that a total of 771,405 salmon – equivalent to 88 percent of the fish in the center – perished with the cages sunken at a depth of 295 meters. As such, the mortality present on the seabed is estimated at 2,900 metric tons (MT).
Of the escaped fish, 28,276 were recaptured, corresponding to 27.26 percent of the total escaped fish. Chile’s General Fisheries and Aquaculture Law stipulates that at least 10 percent of the escaped specimens must be recaptured within 30 days of the event, or an environmental emergency is declared.
In the meantime, Chile’s Superintendent of the Environment (SMA) ordered Blumar to take urgent measures at the Caicura center, including environmental monitoring stations; sampling; and underwater monitoring with high-resolution side scan sonar, echo sounders, and bathymetry tools; to evaluate the marine substrate.
Now the question arises as to what to do with the mass mortality. Removing that, and the sunken cages from the Caicura center will not be easy, SMA head Cristóbal de la Maza warned.
“There is a high risk when removing decomposing organic matter, since pockets of hydrogen sulfide can form, which in high concentrations are deadly for people who are part of the work, and can damage the ecosystem if the process is not handled properly,” he told local publication SalmonExpert, adding that the decomposing fish could also deplete oxygen levels, thereby affecting surrounding farming centers.
On the other hand, at depths of 295 meters, the water pressure on the biomass may help to encapsulate the decomposing matter, but “this has to be evaluated by each of the experts hired by Blumar, following our requirements and those of the different authorities.”
Following the event, the maritime authority announced it had presented a lawsuit against Blumar for possible environmental damage.
Photo courtesy of Chile's Superintendent of the Environment (SMA)
