Ghana's Akosombo Dam, Volta Lake Fisheries & Climate Change

In Ghana, the Pwalugu Dam in the Upper East is in the final planning stage. Whereas promoters of Ghana's first dams emphasized the need for generating electricity to modernize and industrialize the new nation, the planners of Pwalugu have focused on water issues. Due to climate change, droughts have had a devastating impact on local agriculture. The dam's primary purpose is an irrigation scheme and flood control. This essay historicizes these concerns by revisiting the Akosombo Dam, Ghana's largest hydroelectric dam, completed in 1965. The discussion juxtaposes personal recollections of dam-affected communities with reports by administrators, biologists, and social scientists. The essay draws on government records, scientific studies about Volta Lake, and oral histories. Ultimately, it argues, builders and administrators of the Akosombo Dam failed to address most water issues, despite ample knowledge about their existence. One hopes that these shortcomings will not be repeated in the Pwalugu project.

Factors Affecting the Prevalence of Schistosomiasis in the Volta Region of Ghana

The construction of the Akosombo dam in 1964 and the Kpong dam in 1981 on the Volta River created the Volta Lake in Ghana, West Africa. The purpose of this study was to examine the effects of dam construction on schistosomiasis prevalence. Several reports from numerous sources which together spanned a period of time from before the dams were built to recent years were analyzed. Four representative villages were chosen based on their locations with respect to the dams. Also examined were the efforts made by local health authorities to combat the current problem and to what degree their efforts have been successful. A marked rise in schistosomiasis prevalence following dam construction is observed in villages located in close proximity to the Volta Lake. In villages where aggressive action has been taken to correct this problem, a significant decrease in disease prevalence can be seen, demonstrating the importance of implementing proper disease control measures.

Aspects of Reproductive Ecology of Chrysichthys Auratus in the Volta Lake, Ghana

The study was conducted in 2018, on the Chrysichthys auratus in the Volta Lake, due to its socio-economic importance to the many and varied dependent fishermen, fish processors and fish traders. The objective was to determine the reproductive strategy to facilitate sustainable management of the fish stocks. A total of 452 fish samples collected on monthly basis were measured, weighed and dissected for determination of, sexual maturity, sex ratio, gonadosomatic index GSI, hepasomatic index HSI, condition factor k, visceral fat index VFI, and monthly stomach fullness in relation to sexual maturity. According to the length at first maturity determined, 89% of the female fish caught, fell below that critical length, suggesting growth overfishing, attributed to size and sex selective tendencies of bamboo pipe fishing. During gonad development, the correlation of the GSI to the HSI and the VFI was inverse and insignificant but in the post gonad development phase it switched to a positive and insignificant relationship. The point of switch, in September, was synonymous with spawning and indicative of the spawning period. It was concluded that the reproductive strategy was to time the spawning process, in September, to coincide with the upwelling phenomenon (June – September), associated with fish food abundance, thereby enhancing the survival of the offspring. A seasonal ban on fishing and a total ban on bamboo pipe fishing were recommended.

Aquaculture-Mediated Invasion of the Genetically Improved Farmed Tilapia (Gift) into the Lower Volta Basin of Ghana

The need for improved aquaculture productivity has led to widespread pressure to introduce the Genetically Improved Farmed Tilapia (GIFT) strains of Nile tilapia (Oreochromis niloticus) into Africa. However, the physical and regulatory infrastructures for preventing the escape of farmed stocks into wild populations and ecosystems are generally lacking. This study characterized the genetic background of O. niloticus being farmed in Ghana and assessed the genetic effects of aquaculture on wild populations. We characterized O. niloticus collected in 2017 using mitochondrial and microsatellite DNA markers from 140 farmed individuals sampled from five major aquaculture facilities on the Volta Lake, and from 72 individuals sampled from the wild in the Lower Volta River downstream of the lake and the Black Volta tributary upstream of the lake. Our results revealed that two farms were culturing non-native O. niloticus stocks, which were distinct from the native Akosombo strain. The non-native tilapia stocks were identical to several GIFT strains, some of which showed introgression of mitochondrial DNA from non-native Oreochromis mossambicus. We also found that the non-native cultured tilapias have escaped into the wild and interbred with local populations, and also observed potentially admixed individuals on some farms. Our results highlight aquaculture as a vector in the spread of invasive non-native species and strains, and underscore the importance of genetic baseline studies to guide conservation planning for wild populations.