Oxygen Deprivation Caused Fish Kill, We’re Not Sure How …UG marine scientists

he Department of Marine and Fisheries of the University of Ghana (UG) has said that preliminary investigation into the cause of the recent fish kill on Ghana’s beaches was due to a sudden drop in the levels of soluble oxygen in the water.

And the sudden drop in these oxygen levels was likely caused by changes in the climate.

“The University of Ghana’s Department of Marine and Fisheries Sciences carried out a preliminary scientific assessment of the situation. Results from water quality analyses showed that most parameters required for life in the ocean were within acceptable limits, with the exception of Chemical Oxygen Demand (COD), which was significantly higher than expected. This oxygen demand would most likely create a condition of stress on living organisms that depend on dissolved oxygen in the water body,” a statement from the researchers said.

“It is interesting to note that a few days to the fish kill, there was a sudden drop in sea surface temperature as observed from satellite imageries over the coast from Cote d’Ivoire to Togo. This is most likely an indication of upwelled water from the bottom of the ocean, probably carrying low oxygen concentration.”

However, the scientists said they are not sure what exactly triggered the causes of the changes. “At this stage, we do not have any data on what triggered these incidents.”

The mystery has therefore become a battle cry for the establishment of an ocean monitoring system in the country. “It requires that an ocean monitoring programme is established as a matter of urgency.”

It would be recalled that from 2nd April 2021, the media space was awash with news that there is mass fish kills around some beaches of the country with dead dolphins, tuna and other marine mammal species suddenly washed ashore.

The development became a source of worry with authorities fearing that the fish kill may have been triggered by poisoning of sorts, particularly from commercial fishing vessels owned by Chinese companies.

According to the UG Marine and Fisheries Science Department, preliminary investigations show the fishes may have asphyxiated to death because of the sudden drop in the levels of soluble oxygen.

It took stock of the fish species killed as including both demersal (bottom-dwellers), and pelagic (above bottom dwellers); of both small and large sizes. “We confirm the identification of the marine mammals found dead along the coast as the melon-headed whale (Peponocephala electrica), a dolphin belonging to the Cetacean order.”

The department took the opportunity to reiterate its call for the nation to acquire a research vessel that would help with carrying out regular monitoring of our coastal waters. “We depend very much on the marine living and non-living resources for a significant portion of our national wealth. It is implicit that we protect this asset through regular monitoring so as to avert any future calamity.”

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