The export of shrimps to the European Union was one of the mainstays of the Beninese economy. It is an income-generating activity for the populations living along Lake Nokoué. The lack of a fisheries management strategy has caused a drastic decline in shrimp’s production in Lake Nokoué since 2003. To remedy this problem, it is necessary to hypothesize on their spatial-temporal dynamics in the Lake Nokoué-Cotonou channel complex. This is investigated by combining a literature review on their life cycles and habitat suitability with spatial-temporal evolution of salinity obtained from in-situ observations. The literature review reported four (04) potential families of shrimp species whose part of their life cycle is common to the ecology of Lake Nokoué: Penaeidae (Penaeus); Palaemonidae (Macrobrachium); Atyidae (Atya) and Desmocarididae (Desmocaris). The overall results in relation to the life cycle of the shrimp species indicate that adults of the Macrobrachium, Atya species have a favorable environment in Lake Nokoué from August to November and their larvae must remain in the lake from December to June to ensure their survival. The species of the genus Desmocaris, which carry out their entire life cycle in fresh water, can stay in Lake Nokoué from August to November. The species of the genus Penaeus have a favorable environment in Lake Nokoué from December to June but their larvae can only survive in the sea. Species of the genus Caridina (freshwater) and Palaemon (estuary and marine) belonging to the family Palaemonidae can however be found in Lake Nokoué because of their wide distribution on the West African coast although they are not reported in Benin. This research makes it possible to predict the presence or absence of shrimp genera in a lake system, based on their life cycle. Based on the results obtained, we suggest a ban on fishing in Lake Nokoué between December and February and a ban on shrimp fishing in the Cotonou canal for a good management of the shrimp stock in Benin.

BackgroundThe export of shrimp to the European Union was one of the mainstays of the Beninese economy. It is an income-generating activity for the populations living along lake Nokoué. The lack of a fisheries management strategy has caused a drastic decline in shrimp production in lake Nokoué since 2003. To remedy this problem, it is necessary to hypothesize on their spatio-temporal dynamics in the lake Nokoué-Cotonou channel complex. This is investigated by combining a literature review on their life cycles and habitat suitability with spatio-temporal evolution of salinity obtained from in-situ observations.ResultsThe literature review recognizes the presence in southern Benin of species of the genus Macrobrachium, Atya and Desmocaris (seven, two and one respectively) and five species of marine shrimps belonging to three genera: the genus Penaeus, the genus Holthuispenaeopsis and the genus Parapenaeus. From information on the ecology and physical environment it is shown that adults of the species of the genus Macrobrachium and genus Atya have a favorable environment in lake Nokoué from August to November, their larvae must remain in the lake from December to June to ensure their survival. The species of the genus Desmocaris, which carry out their entire life cycle in fresh water, can stay in lake Nokoué from August to November. The species of the genus Penaeus can find a favorable environment in lake Nokoué from December to June but their larvae can only survive in the sea. Finally, the species of the genus Holthuispenaeopsis and Parapenaeus spend their entire life cycle at sea.ConclusionsThis work allows understanding contrasted life cycles of shrimp’s genera Macrobrachium and Atya compared to Penaeus in a complex ecosystem characterized by strong saline variation. This research allows to predict the presence or absence of shrimp’s genera Macrobrachium, Atya, Desmocaris and Penaeus in a lake system, on the basis of salinity distribution, for a sustainable management of their exploitation.