The Minister of Fisheries and Aquaculture Development, Hawa Koomson, has had her first share of Ghanaian Twitter scoffing this year since her responses to questions during her ministerial vetting in February 2021. This time around, Hawa Koomson is trending on Ghana Twitter for stating the preliminary findings of the cause of the mass mortality of fishes in Osu to be fish stress.
A few days ago, news of a mass fish mortality including over 60 dolphins washed ashore along the coasts of Axim, Osu and Keta in three different regions in Ghana was reported which has become of great concern to both Ghanaian and international audiences. In view of this, the minister announced an inter-agency investigation into the cause of the mass fish mortality, where both the Environmental Protection Agency and the Fisheries Ministry are reported to have started investigations along the shores of Osu.
It is on this premise that Koomson revealed the preliminary findings conducted on fishes along the Osu shore to be fish stress. This news has been received with derision and disbelief by Twitter users possibly as a result of public mistrust from Koomson’s answers given at her ministerial vetting.
Fish stress not a new concept
We find that fish stress is not a ‘Hawa Koomson term,’ nor is it explained in ‘human stress’ terms as some have assumed.
To begin with, Koomson’s statement is an update given according to the preliminary findings revealed by a fish health specialist at the Fisheries Commission, Dr. Peter Zedda, whose Fish Health Unit and the Scientific Survey Division conducted investigations on a sample of the fishes from the Osu beach.
Having stated the preliminary findings for the cause of death to be a stress factor found in the fishes, Dr. Zedda added that “further pathological investigations on the gills of the fish are ongoing and any new development will be made public”
Furthermore, a research paper titled “Biology of stress in fish: fish physiology” published in Elsevier sheds light on the concept of stress in fish.
It explains that stress is a natural physiological response of fish to threatening situations, similar to all vertebrates such as birds, reptiles, fish, mammals and amphibians. It adds that fishes respond to stress when they perceive a stressor. When fishes are exposed to repeated or prolonged stress, they experience negative effects in relation to resistance to diseases, growth, metabolism, development, behaviour and reproduction.
It is noteworthy that different species of fish vary in their responses to stress based on the environmental history of the fish, their present ambient environmental conditions, and the fish’s present physiological conditions.
Additionally, a book titled “Fish Stress and Health in Aquaculture,” published by Cambridge University Press, shows that severe stress in fish can cause mortality. It highlights the environmental factors that could cause stress in the different species of fish to be anaesthetic, acclimation temperature, external salinity, nutrition, water quality, time of day, overhead light, fish density. and background colour. It further shows that hormonal, biochemical, and physiological conditions of fish can also cause them to respond to stress.
Several other studies on aquatic life such as this and this corroborate the evidence of stress in fish and its consequential death in the species.
Ghana is not an exception
Meanwhile, the mortality of fish, especially dolphins is not exclusive to Ghana. Earlier this year and last year, 111 dolphins and 52 dolphins were found dead along the coast of other countries in Africa such as in Mozambique and Mauritius.
In the case of Mauritius, the fisheries ministry’s investigations attributed the cause of the death of 52 dolphins found on the coast of the Indian Ocean island to be barotrauma – a phenomenon caused by rapid or extreme changes in air pressure.
While investigations are yet to be concluded on the cause of the mass mortality of fishes in Ghana, the preliminary result of fish stress is not unfounded as it exists within aquatic life.