Genetic conservation and social implications of hybrid catfish farming in central Thailand.

摘要

Using the case of hybrid catfish (native catfish, Clarias macrocephalus × African catfish, C. gariepinus) farming in central Thailand, I combined sociological and genetic studies to explore the connections between natural aquatic resources and hybrid catfish farmers. My purpose was to determine how these connections affect the status and future of aquatic biodiversity conservation and livelihoods of small-scale farmers.; I documented farmers' aquaculture practices using observations and interviews with the focus on production inputs and environmental hazards posed by hybrid catfish farming. Important aquatic resources for commercial production include broodstocks and fresh water. Environmental hazards include escape of hybrid catfish, release of nutrient-rich discharge and spread of diseases.; Escaped hybrid catfish may intermate with wild native catfish individuals. Producing hybrid catfish using introgressed native catfish individuals can result in loss of hybrid vigor for growth or disease resistance. I assessed genetic introgression of African catfish genes into native catfish populations. Based on six genetic markers, I detected low levels of introgression (1–9%) of African catfish alleles in six broodstock and wild native catfish populations. I also evaluated existing genetic diversity within and among these populations using three microsatellite DNA markers. Wild native catfish had moderately high genetic variation within (heterozygosity = 0.34–0.89) and among populations (exact test, p 0.001), indicating considerable genetic structure that could be altered by human influences. Native catfish populations were genetically distinct at a regional level within Thailand.; Current primary actors take limited conservation actions although farming practices that minimize production loss due to flood or disease can reduce negative environmental consequences. Although this low level of action is a conservation challenge, farmers' desire to sustain livelihoods and openness to innovation offer significant opportunities for engaging them in conservation activities. Fish farmers already expressed their concerns over the declining abundance of wild native catfish and eroding genetic quality of catfish broodstocks. They also expected more of a leadership role from the Thai Department of Fisheries (DOF). These results indicate opportunities for the DOF and universities to collaborate with fish farmers to initiate a conservation effort that can foster sustainable use of natural aquatic resources.