Industrial, domestic wastes responsible for coastline fish killing – NORSDRA

The National Oil Spill Detection and Response Agency (NOSDRA) has ruled out hydrocarbon as the major cause of mass fish kill along the nation’s coastline of Bayelsa, Delta and Rivers states.

This is as findings by the Agency shown that the death of a high number of fishes washed ashore were caused by corrosive effects of industrial and domestic wastes dumped into water bodies in the Niger Delta region.

Findings by NOSDRA followed collection of samples of water, sediments and the dead fishes for laboratory analyses.

The Director General of NOSDRA, Idris Musa, who in a press release at the weekend said relevant government agencies were involved in the analyses.

He said it became expedient for the Agency to make explanation on the parameters of concerns that were analysed for the purpose of clarity and understanding.

In the statement made available to the media, the Director General said “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 analyses.

“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 water samples taken at the coastline in Bayelsa State, the values of Cadmium and Iron were higher than the regulatory standards limit”.

According to him, the water samples taken at the coastline in Delta State, the values of Cadmium, Iron as well as Zinc are higher than the regulatory standards limit.

“The Cadmium in water was between 0.079 -0.184 mg/l with an average of 0.158 mg/L This was above the regulatory limit of 0.05 mg/l as well as the control sample which was 0.08 mg/l.

“The value of iron ranged between 1.220 2.064 mg/l with a mean value of 1.699 mg/l. This is higher than the regulatory limit of 1.00 mg/l.

“The Zinc in the water ranged between 0.185 0.465 mg/l with a mean value of 0.238 mg/l. This value is higher than the control sample value of 0.145 mg/l.

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“The value of Copper in the sampled dead fishes was 0.66mg/kg as against 0.5 mg/kg in the regulatory limit.

“In the water samples taken at the coastline of Rivers State, all the parameters of concerns analysed namely, TPH, PAH, BTEX, Chromium, Copper and Mercury were within the regulatory limits except dissolved oxygen which mean value of 5.55 mg/l was slightly higher than the regulatory limit of 4 – 5 mg/l”, he explained.

In the light of the foregoing, the DG said noting that 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.

Musa said “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 State.

“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.

The Agency, as a result, cautioned that
as a nation, Nigeria need to pay more attention to the activities of those illegally carrying out fishing in territorial waters to guard against possible dumping of wastes as well as unwanted aquatic species.