Methods of disrupting germ cell migration and development in a fish embryo by inducing targeted expression of Sdf-1a or Lif and disruption of the Sdf-1a gradient or a Lif signaling pathway in the fish embryo have been developed. Plasmid constructs containing a gene encoding Sdf-1a or Lif and a gene encoding a signaling sequence for targeted expression of Sdf-1a or Lif have been generated. The plasmids will be administered to a fish or a population of fish to reproductively sterilize the population with efficacy of up to 100%. Transgenic fish of this invention are reproductively incompetent of genetically contaminating a wild fish population.