CVM GFI #257 (VICH GL57) Studies to Evaluate the Metabolism and Residue Kinetics of Veterinary Drugs in Food-Producing Species: Marker Residue Depletion Studies to Establish Product Withdrawal Periods in Aquatic Species(Draft)(CVM GFI #257 (VICH GL57) 研究评估兽药在食品生产物种中的代谢和残留动力学：标记残留消耗研究以确定水生物种的产品撤药期（草案）)