Predicting total lengths of spectacled Caiman (Caiman crocodilus) from skin measurements: A tool for managing the skin trade

Colombia uses a closed-cycle captive breeding program for producing Caiman crocodilus (mostly C. c. fuscus) skins for export. Skin size limits are used as a regulatory measure to exclude illegal wild-caught adults entering legal trade. However, the size limits employed were not well defined by morphological endpoints, and the degree of shrinkage between raw and processed skins was not well grounded in science. Thus, trimming and cutting of skins to meet market demand makes compliance with the limits problematic. We examined the relationship between C. crocodilus total length (TL) in freshly culled animals and the size of whole skins and skin pieces at different stages of preservation and tanning (raw wet-salted, wet blue, crust, and finished leather) in 276 farm-raised C. crocodilus (423-2,210 mm TL). We present formulae for accurately predicting the TL of Caimans from which whole skins or skin pieces originated. To account for tail tip amputations, we used standardized total length (TLST). The results provide resource agencies in Colombia better tools for establishing meaningful size limits, and provide the Parties to the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) with a better mechanism for assisting Colombia with compliance. This approach may have application to the regulation of other species of reptile in trade, where size limits are part of the regulatory procedures.