CONSERVATION:
Historically widely distributed throughout the Amazon basin and beyond. However, once populations of both Crocodylus acutus and Crocodylus intermedius became severely depleted due to over-zealous commercial hunting, attention was turned to those species with slightly smaller or lower-grade skins. The skin of M. niger produces a shiny, black leather. Hunting was directed very intensely towards M. niger during the 1950s, only declining in the following decade when commercial interests turned to Caiman crocodilus. Some areas were affected more severely than others, with hunting pressures continuing into the 1970s and beyond. Estimated to have been reduced in numbers by 99% in the space of the last century. Population recovery today is impeded both by continued illegal hunting and through increased competition with the more numerous Caiman crocodilus. This latter species has moved into areas once inhabited by M. niger and proliferated due to its increased reproductive capacity. Hunters can take both of these species with ease. Habitat destruction through deforestation and burning of swamplands (French Guiana) continues the onslaught.
Little information was available about this species until the 1980s, when research was carried out into both biology and population ecology. There is still much to be learned however. Although some data are available concerning interactions with other South American caiman species, the dramatic decline in populations of M. niger have obscured trends. Some partitioning of habitat is apparent, however. Population declines have been correlated with a decrease in fish production in rivers, due to the removal of the nutrient-recycling component in the ecosystem as provided by M. niger. Both piranha and capybara have benefited from the reduction of their main predator. This has led to increased agricultural and livestock losses. Survey data, which is available throughout most of the species' range, reveals drastically reduced populations. Further survey work is required to update this information. M. niger is severely depleted in over half of the countries in which is occurs, and considered to be depleted in the rest. Only populations in isolated locations remain stable.
Management programs centre around the legal protection of remaining wild populations, but these laws are difficult to enforce effectively. The skins can be difficult to differentiate from those of C. crocodilus.Captive breeding and reintroduction was initiated in Bolivia in 1990. Both of these conservation strategies need to be extended and implemented as effectively as possible in other countries.
MORE INFORMATION:
For more information on distribution and conservation issues for this species,see the CSG Action Plan resource.
SIGNIFICANT REFERENCES:
Asanza, E (1992). Population dynamics, ecology and conservation of the black caiman, Melanosuchus niger in Ecuadorian Amazonia. In: Crocodiles. Proceedings of the 11th Working Meeting of the Crocodile Specialist Group. IUCN, Gland, Switzerland. pp.22-30
Brazaitis, PJ, Rebêlo, GH, Yamashita, C, Odierna, EA & Watanabe, ME (1996). Threats to Brazilian crocodilian populations. Oryx 30(4): 275-284
Fittkau, EJ (1973). Crocodiles and the nutrient metabolism of Amazonian waters. Amazonia 4:103-133
Herron, JC (1991). Growth rates of black caiman, Melanosuchus niger, and the spectacled caiman, Caiman crocodilus, and the recruitment of breeders in hunted caiman populations. Biol. Conserv. 55:103-113
Herron, JC, Emmons, JE & CADLE, JE (1990). Observations on reproduction in the black caiman, Melanosuchus niger. J. Herpetology 24(3): 314-316
Magnusson, W.E., Da Silva, E.V. & Lima, A.P. (1987). Diets of amazonian crocodilians. J. Herpetology. 21:85-95
Pacheco, LF (1990). Feeding, reproduction and growth in captive Melanosuchus niger. In: Crocodiles. Proceedings of the 10th Working Meeting of the IUCN/SSC Crocodile Specialist Group. IUCN, Gland, Switzerland. pp. 109-122
Pacheco, LF, Aparicio, J & Thorbjarnarson, JB (1991). The first reintroduction of black caiman, Melanosuchus niger, into the wild. Herp. Review 22(3): 90-91