Commercial farming threatens Chinese Giant Salamander conservation through disease, introgression and overexploitation.

Abstract

The Chinese giant salamander (Andrias davidianus; CGS), endemic to China and Critically Endangered, has been identified as the amphibian species most in need of conservation action1. Since 2004, a rapidly growing industry to farm CGS for food, subsidised in order to diversify and bolster the rural economy and employment opportunities, has developed throughout much of China, centred on Shaanxi Province.

By mid-2012 at least 141 CGS farms had been licensed in the province, with many more farms unrecorded. In 2011, 2.6 million farmed CGS were documented in Shaanxi Province alone. Wild-caught CGS continue to be in demand for breeding farms even though their capture is illegal. This is partly due to problems in getting > F1 animals to breed and partly due to huge (up to 100%) losses of farm stock from disease epidemics and the consequent requirement to restock affected farms2. This demand for breeding stock, which can command very high prices, has driven recent overexploitation and near-depletion from the wild.

We visited CGS farms during outbreaks of fatal disease and, using PCR, we identified Ranavirus infection as the cause2. Thirty-nine of 43 additional farms surveyed reported that they had suffered disease outbreaks consistent with ranaviral disease. Three of the four farms that did not report disease held stock of ≤ 3,000 animals, lower than the mean number of 8,354 CGS per surveyed farm. The industrial-scale farming, high stocking densities, and trade in animals across China in the absence of biosecurity measures has led to a system that has fostered the propagation and spread of infectious disease.

Genetic screening of wild and farmed CGS has identified geographic structuring of wild salamanders but genetic mixing and hybridisation of farmed animals3. The current structure and management of the CGS farming industry presents conservation threats to extant wild CGS (and possibly other wild fauna) through the discharge of contaminated farm wastewater or the escape of infected individuals to the wild. Additional disease and genetic threats to CGS conservation are posed by the Chinese government-sponsored conservation action of purchasing farmed animals for release into the wild without adherence to IUCN guidelines, such as pathogen or genetic screening, identification of suitable habitat or post-release monitoring.

Complete separation of farmed and wild CGS populations and improved CGS farm management, including the quarantining of new stock and the disinfection of waste-water, is recommended in order to reduce disease risks to both farmed and wild animals. The number and native locations of CGS evolutionary significant units should be identified and in situ protection measures put in place and enforced. A CGS conservation action plan should be developed and, if conservation breeding and release is an identified requirement, this should be conducted separately from commercial farming and should follow IUCN guidelines.

References 1. Isaac, N.J.B., Redding, D.W., Meredith, H.M.R. & Safi, K. (2012) Phylogenetically-informed priorities for amphibian conservation. PLoS ONE 7, e43912.

2. Cunningham, A. A., Turvey, S. T., Zhou, F., Meredith, H., Guan, W., Liu, X., Sun, C., Wang, Z. & Wu, M. (2016) The development of the Chinese giant salamander (Andrias davidianus) farming industry in Shaanxi Province, China: conservation threats and opportunities. Oryx 50, 265-273.

3. Yan, F., Lü, J., Zhang, B., Yuan, Z., Huang, S., Wei, G., Mi, X., Zou, D., Chen, S., Wu, M., Xiao, H., Liang, Z., Tapley, B., Papenfuss, T. J., Cunningham, A. A., Murphy, R. W., Zhang, Y. & Che, J. The Chinese giant salamander exemplifies the hidden extinction of cryptic species. Submitted.