Concern has been raised about the lack of population data for the Nile crocodile Crocodylus niloticus in the lower/middle Zambezi valley. This area is important for conservation as well as being a source of crocodile eggs and adults for the ranching industry. Two spotlight surveys, in 2006 and 2009, were used to estimate population size, structure and trends. A stage-structured matrix model was parameterized from existing literature and the expected predictions were compared to those observed. The survey data suggests a population increase since 2006. Crocodile density was greatest (3.1 km−1) in the areas of increased wildlife and habitat protection and lowest (1.4 km−1) in areas of increased human presence. The predicted population stage structure differed to that observed, suggestive of a population not at equilibrium. Data on offtakes of crocodile eggs and adults would be useful for examining why this is the case. Continued monitoring of the wild population is necessary, to evaluate the trend of an increasing crocodile population, and additional demographic data for modelling purposes would be desirable.

A survey on the Tagant Plateau, Mauritania, to design a reserve for the crocodile Crocodylus niloticus revealed that the area is occupied by a crocodile population larger than expected. Crocodiles occur in lakes and pools along seasonal rivers that form an inner hydrographical network. Reported movements of individuals during the summer floods suggested that it is necessary to protect the whole 700 km-long hydrological network to preserve inter-pool connectivity. However, the basin is occupied by 40,000 people that are completely dependent on water from the hydrological network. Thus it was important to propose a reserve network that would reconcile both the protection of biodiversity and human use of water resources. Considering the symbolic role of crocodiles for many Mauritanians, the acceptance of their presence by the people of Tagant, and the increasing use by tourism agencies of some pools for crocodile-watching, the species may be a good focal species for promoting the conservation of the whole hydrological network of the Tagant Plateau.

In 1998 and 1999, relict populations of the Nile crocodile Crocodylus niloticus were rediscovered in south-eastern Mauritania, 70 years after the last reports of their existence and 6 years after the IUCN Species Survival Commission listed them as extirpated in that country. Crocodiles' were found in four different types of wetlands, herein described. Preliminary observations on their natural history and their interactions with humans are provided, and the main threats and the prerequisites for their protection are discussed.