By Chuks Oyema-Aziken
The National Oil Spill Detection and Response Agency (NOSDRA) has blamed anthropogenic activities as being partially responsible for the numerous dead fishes washed ashore the Nigerian Coastline in Bayelsa, Delta and Rivers States.
NOSDRA Director-General, Alhaji Idris Musa, in a statement explained It was the outcome of investigation by the agency in the several dead fishes littered along the coastlines of the area.
He said the investigation noted that most industrial and domestic wastes which contain heavy metals such as cadmium, iron, zinc, and copper found their way into drainages and onward transfer to the water bodies.
He explained that the deleterious impact of such may be negative to aquatic species, other mammals and even human beings.
He said the investigation was carried out with the collaboration of other relevant agencies with mandate on the marine environment such as the Nigerian Maritime Administration and Safety Agency (NIMASA), Nigerian Institute of Oceanography and Marine Research (NIOMR), National Environmental Standards and Regulations Enforcement Agency (NESREA), and the Federal Institute for Fisheries Research.
He said the team visited aforementioned areas to pick samples of water, sediments and dead fishes for laboratory analyses.
He said that samples collected from Bayelsa, Delta and Rivers states did not show any sign of hydrocarbon as cause of the problems.
He said: “The results of the laboratory were perused, and we make explanation on the parameters of concerns that were analysed for the purpose of clarity and understanding. As earlier mentioned, the findings did not show hydrocarbons (oil) as the possible cause of the death of the fishes.
“In the course of the analyses, Total Petroleum Hydrocarbons (TPH), Polycyclic Aromatic Hydrocarbon (PAR), Benzene, Toluene Ethylene and Xylene (B TEX) were within regulatory standard limits in water, sediments and fish tissue analysed.
“However, there were some heavy metals such as Cadmium, Chromium Copper, Zinc and Iron, that exceeded regulatory standard limits in the coastlines of the three aforementioned States.
“In the light of the foregoing, hydrocarbons were not responsible for the death of the fishes. The plausible cause(s) could partially be attributable to other anthropogenic activities which are probably land-based.
“In this case, while it is commonly observed that most industrial and domestic wastes which contain heavy metals such as cadmium, iron, zinc, copper found their ways into drainages and onward transfer to the water bodies; their deleterious impact may be negative to aquatic species, other mammals and human beings.
“The main sources of these are batteries, galvanised pipes, fertilisers, sewage sludge and plastics.
“Such may be the case in the analyses of dead fishes found at the coastline in Delta and Bayelsa states where chromium was found in fish tissue.
“Copper was also found in the fish tissue sampled in Delta State, but not in those of Bayelsa and Rivers States.
“Furthermore, a sudden release of heavy metals is not likely to kill fishes except those trapped at the point of release because, cadmium in particular is highly toxic.
“Long term accumulation (chronic) rather than short term (acute) heavy metals could cause the death of fishes.
“It is also curious that a specific species of fish is allegedly involved in the circumstance under consideration.
“NOSDRA therefore urged that the country should pay more attention to the activities of those illegally carrying out fishing activities in the territorial waters to guard against possible dumping of wastes as well as unwanted acquatic species”.