Image: Productos del Mar Ventisqueros S.A. / FIS

Harmful Algal Bloom in the Group of Salmonid Concessions 17B

CHILE
Monday, April 22, 2024, 01:00 (GMT + 9)

The Servicio Nacional de Pesca y Acuicultura (Sernapesca) of the Los Lagos region reported on the presence of a new harmful algal bloom event (HAF) that is causing mass mortality (MM) in Hornopirén and that affects the Group of Concessions of Salmonids (ACS) 17B, Los Lagos region, due to the presence of the microalgae Heterosigma akashiwo.

Source: Sernapesca. Clic on the image to enlarge

Of the 14 centers currently operating in ACS 17B, 6 have activated action plans for HAB, and of these, 2 have activated their action plans for mass mortality. The total mortality reported by the Multi-X S.A. companies and Productos del Mar Ventisqueros S.A. to Sernapesca corresponds to 288.3 tons in total, information that is updated daily. From the centers that are experiencing massive mortality, the withdrawal of 284 tons with final destination to the Fiordo Austral and Salmon Oil S.A. reduction plants has also been notified.

Cristian Hudson, Regional Director of Sernapesca Los Lagos indicated that, “Since the activation of the contingency plans we have been monitoring and monitoring their correct compliance. As for the centers that have declared mortality, we have been constantly verifying that their correct withdrawal is carried out within the established deadlines.”

According to the phytoplankton reports sent by the companies, the concentrations of H. akashiwo remain high, so as a preventive measure, centers 101283, 101541, 100991 and 103923 requested the transfer of fish to other centers, movements that Sernapesca authorized within the framework of the current aquaculture pre-alert.

In this sense, the regional authority also mentioned that they will continue to monitor the affected and surrounding ACS in case they register an increase in the concentration of the microalgae.

After attachment to the gill of the fish, algal cells embed into gill tissues using exoenzymes. The presence of the algal cells stimulates mucus secretion, followed by the algal cells producing neurotoxins, and reactive oxygen species that cause asphyxiation in the fish. In addition, hemolysin compounds can lyse the erythrocytes to scavenge nitrogen and iron. Source: MDPI

The high concentration of the Heterosigma akashiwo microalgae produces a sedative/anesthetic effect in salmonids, which can cause their death. It should be noted that this microalgae does not correspond to the so-called “red tide”, so bivalve mollusks or other fish are not affected.

Source: Sernapesca (Translated from the original in Spanish)

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