The decline of the Nile crocodile population in Loskop Dam, Olifants River, South Africa

Abstract

The apparent decline in the number of Nile crocodiles present in the Loskop Dam prompted a study to determine the number, size and distribution of Nile crocodiles now present in the reservoir. The number of crocodiles in the Loskop Dam was surveyed using aerial counts and spotlight counts. Surveys revealed the presence of a very low total number of crocodiles and also a poor distribution of crocodiles in the different size classes over almost 30 years since 1981. Eight surveys carried out between 2001 and 2010 revealed that the distribution pattern of crocodiles in the Loskop Dam did not vary between winter and summer. These distribution patterns indicate that crocodiles occur most frequently in the eastern and western inlets and not in the main basin of the dam. Thirteen crocodiles were re-introduced into the dam during March 2007; however the August 2009 spotlight survey results indicated that none of these animals had survived.

Blood lead concentrations in free-ranging Nile crocodiles (Crocodylus niloticus) from South Africa

“…In South Africa the species is IUCN red-listed as Vulnerable (Marais 2014), with remaining viable populations restricted to protected areas and waterbodies under some degree of conservation management. There are recent declines in major populations (Kruger National Park, Flag Boshielo Dam, Loskop Dam, Ndumo Game Reserve, iSimangaliso Wetland Park) due to poaching and indiscriminate killing (Calverley and Downs 2014a), loss of nesting habitat (Combrink et al 2011) and environmental degradation (Botha et al 2011;Ferreira and Pienaar 2011). These trends are concerning not only with regard to the long-term persistence of the species but also for the ecological integrity and environmental health of aquatic ecosystems in northeastern South Africa (Combrink et al 2013).…”

The Entangled Relations of Humans and Nile Crocodiles in Africa, c.1840-1992

“…Crocodiles within and outside protected areas are also under pressure from agricultural and industrial development, notably dam building, irrigation and water pollution and competition with humans for habitat and food. 107 This paper outlines major shifts in European attitudes to Nile crocodiles, particularly in terms of policy and management in the twentieth century. In most cases the shift to 112 genetic research suggests the Nile crocodile should be split into two species, providing some credence to stories that ancient Egyptian priests kept the smaller, more amenable species for ceremonial purposes: Evon Hekkala, et al, "An ancient icon reveals new mysteries", 4210.…”

Distribution and habitat suitability of Nile crocodile (Crocodilus niloticus, L. 1768) in Tekeze River Dam, Tigray, Ethiopia

“…At the time of survey, basic observations were carried out like the physical and vegetative character of the shoreline, crocodile numbers, age-size classification, basking sites, swimming and prey availability by adopting methods used (Whitaker, 2007;Leslie et al, 2011). The size classifications of crocodile are determined based on modifications of methods adopted from Botha et al (2011) and Combrin et al (2011). Accordingly, juveniles are assigned to age-*Corresponding author.…”

“…They are also considered as environmental indicator species, especially for the build-up of contaminants and as apex predators. They contribute also by playing an essential role in the nutrients recycling (Botha, 2011;Ijeomah and Efenakpo, 2011). Meanwhile, crocodiles also represent a good source of income generation through the sale of skin and its meats to tourists as well as through crocodile ranching/farming for enterprises development.…”