For reasons as yet unknown, huge numbers of fish from the same species have been dying on the tourist beaches of Ganabara Bay in Rio de Janeiro, Brazil over the past month, an unprecedented situation that is scaring the population.
The municipal cleaning service have found 20 tons of shads, a particular species of fish similar to sardines and herrings, as well as four sea turtles.
Surprisingly, “the tests proved that it is not a matter of chemical or toxic contamination of water,” declared the oceanograph David Zee to AFP, from the State University of Rio de Janeiro (UERJ).
The fisherpeople have complained of being forced to buy fish to resell, as their weekly wage has been cut by more than half, and have blaimed the activities of the giant national oil company, Petrobras.
“The fisherman aren't going to poison the water as it's their lifeline. This is not because of fishermen. Why are [the authorities] not checking the activities of the petrochemical industry? Why are they not checking the refineries? It is very clear that we are witnessing a crime against the environment. What we need to know is who is responsible and what products are being used," said Alexandre Anderson, president of the Men & Women of the Sea Association to AFP.
Two years ago, the Brazilian general attorney accused the Petrobras company of environmental crime, for contaminating the bay and one of the rivers.
As only one species seems to be involved so far, another possible cause would be thermal pollution: the water would be too warm, therefore diminishing the solvability of oxygen, something the shads are very sensitive to, explained Zee. According to the scientist, this phenomenon would be aggravated by the fact that the circulation and change of water is more difficult in this part of the bay.
Five specimens of shads have been sent for examination on Tuesday to the department of biology of the UFRJ, and the results should be known within the next week.