A PCR-based method for sex identification of critically endangered Formosa landlocked salmon

The extinction risk in a small population depends largely on stochastic factors that affect effective population size. Unbalanced sex ratio, a form of demographic stochasticity, not only reduces the effective population size but also raises extinction risk. Sex identification is fundamental for conservation biology; however, it is extremely difficult to do in Formosa landlocked salmon Oncorhynchus masou formosanus. Because sexual dimorphism in landlocked dwarf form Formosa landlocked salmon is minimal, we developed a simple and noninvasive PCR-based method to identify sex in this critically endangered species. The OtY2m primers (derived from OtY2) amplified the male-specific marker (OtY2) in Formosa landlocked salmon. In addition, we provide a valuable tool for detection of sex ratios in wild populations for conservation management. This study contributes useful information to estimate the effective population size and analyze population viability of Formosa landlocked salmon.