Browsing by Author "Dzidzornu, K.E.A."
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Item Investigations into Hatchery and Nursery Operations for the Culture of the Freshwater Prawn (Macrobrachium Vollenhovenii, Herklots 1857) in Ghana(University of Ghana, 2018-07) Dzidzornu, K.E.A.The study was conducted to demonstrate hatching and larval development of the African River Prawn Macrobrachium. vollenhovenii Herklots, 1857) and to establish the spatial and temporal distribution of the prawns and related crustaceans in the Lower Volta River from Torgorme (Akuse) to Ada with focus on the Volta Estuary of Ghana. The ecological survey was undertaken from August 2013 to July 2014 followed with aspects of reproductive biology of the M. vollenhovenii from August 2014 to July 2015 and then the hatching and larval development of the from January to December 2016. Fisheries dependent data was collected together with experimental prawn fishing. The species encountered included Atya gabonensis (Giebel, 1875), Macrobrachium macrobrachion, (Herklots, 1851), Macrobrachium vollenhovenii and Penaeus spp. Comparatively more Penaeus spp. were sampled in the dry months (November to January) in more saline zones while Macrobrachium spp. were more in the rainy months (May to July) in the more freshwater zones. The dominant species in the estuary was the M. vollenhovenii (72.52%) with male to female ratio of 1:1.3 and non-berried to berried females ratio as 1:1.7. The berried females were obtained throughout the year with increased numbers and larger ones in the rainy season. The size and weight of gonad correlated positively with size of berried females and appeared to be a function of the number rather than the size of eggs. Out of four treatment media (Artificial Sea salt, Freshwater, Seawater and Rock salt) used for the larval development, the Freshwater medium could not support the life of the larvae after 48 hours. The 8th Larval stage (ZVIII) was observed from the 23rd day of culture in both Seawater and Artificial Sea Salt media. Survival rate correlated negatively with stocking densities of 50, 100, 150 and 200 larvae/liter, an indication that thinning is necessary as the larvae grow from one stage to another. Survival rates in the 50 larvae/liter were 36.8%, 30.8% and 25% in the Seawater, Artificial Sea salt and Rock salt treatments respectively. From the results, M. Vollenhovenii larvae could be hatched and developed for culture in the grow-out process to boost prawn culture in Ghana.Item Studies on the Growth Pattern of the Penaeid Shrimp Penaeus Notialis (Perez-Farfante) in Ponds Manured with Chicken Droppings(University of Ghana, 2003-06) Dzidzornu, K.E.A.; Darpaah, G.A.; Dfori-Danso, P.K.; University of Ghana, College of Basic and Applied Sciences, School of Biological Sciences, Department of Marine and Fisheries SciencesA study was conducted on the growth pattern of the penaeid shrimp, Penaeus notialis, in earthen ponds at the Volta Estuary of Ghana. The ponds were treated with chicken manure at the rate of 0 kg/ha (control), 100 kg/ha, 200 kg/ha, and 300 kg/ha respectively. The culture period was divided into two phases; the first phase covered a period of 90 days and the second phase took 180 days. Growth rates established at the end of the 90 days of culture were 0.04 - 0.13 g/day that resulted in the yield of 128.03 kg/ha, 138.00 kg/ha, 168.88 kg/ha and 243.60 kg/ha in the 0 kg/ha, 100 kg/ha, 200 kg/ha and 300 kg/ha manure treatments respectively. The growth rates at the end of 180 days of culture were 0.04 - 0.07 g/day that resulted in yield of 258.72 kg/ha, 261.05 kg/ha, and 327.18 kg/ha in the 0 kg/ha, 100 kg/ha and 200kg/ha treatments respectively. Analysis of Length-weight relationship showed isometric growth during the second half (91 to 180 days) of culture whilst the growth during the first 90 days was not isometric in all the treatments. Regression of total length on Carapace length; Body weight on Carapace length and Body weight on Total length showed strong correlation for both 90 and 180 days of culture periods. Productivity test showed nearly uniform primary production in all the ponds with 100 kg/ha treatments registering the highest value of 3.53 mg/l and 300 kg/ha treatments the lowest value at 1.45 mg/l The results indicated that P. notialis would not be ready for harvest during the first 90 days of growth; at least 5 months of growth is required to attain marketable size. Chicken manure could be used at 200 kg/ha and 300 kg/ha rates, an illustration that shrimp culture development and production in Ghana has a great potential.