Investigations into Hatchery and Nursery Operations for the Culture of the Freshwater Prawn (Macrobrachium Vollenhovenii, Herklots 1857) in Ghana
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Date
2018-07
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Publisher
University of Ghana
Abstract
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.
Description
PhD.
Keywords
Hatchery, Nursery, Freshwater Prawn, Macrobrachium Vollenhovenii, Herklots 1857, Ghana