Monitoring and managing the harvest of tegu lizards in Paraguay
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Despite the ongoing worldwide trade in reptiles, monitoring and management systems are only recently being developed for exploited lizards and snakes. We studied the tegu lizard (Tupinambis spp.) management and harvest monitoring program in Paraguay as a model for commercially exploited reptile management. Tegu lizards are among the most exploited reptiles in the world, with current quotas for Paraguay and Argentina of 300,000 and 1,000,000, respectively. We analyzed demographic data obtained from harvested skins of 2 species of tegu lizards at 2 trade levels (i.e., check stations and tanneries) over an 8-year period. There was significant annual variation in the number, size, and sex ratios of harvested tegus. Sex ratios were consistently male biased. The proportion of small skins in the harvest decreased over time, indicating compliance with the policy to ban commerce of small tegu skins. However, disparities among check stations and tanneries indicated that small skins might have been restretched by middlemen as they were bartered up the trade chain. Our results support the conclusion that tegu lizards are withstanding the harvest in Paraguay. There was no chronological trend of increased take or decreasing size that would indicate overharvest, and there were no indicators of local population decline. However, data on hunter effort are lacking, and it is important to implement a system for quantifying hunter effort and incorporate those data into harvest models. This is the first study to report long-term data on a harvested lizard. The approach we used here can serve as a model for monitoring and management of other commercially exploited terrestrial reptiles.
