Archiva Zootechnica 13:1, 53-59, 2010 53 PCR-RFLP method to identify fish species of economic importance Andreea Dudu, S. E. Georgescu, Anca Dinischiotu, Marieta Costache University of Bucharest, Molecular Biology Center, Bucharest SUMMARY The identification of different fish species by molecular methods has become necessary to avoid the commercial frauds on the fish market. The falsification of fish products derived from valuable species represents a frequent phenomenon due to the substantial profit resulting from selling less expensive products as more demanded and higher priced species foods. Different fish species of a great economical importance like sturgeons and salmonids can be identified by PCR–RFLP. This method is based on the amplification of a specific region from the mitochondrial genome, which is subsequently digested with restriction endonucleases (RE) resulting in species specific restriction patterns that allow to distinguish between the analyzed species. Keywords: salmonids, sturgeons, mitochondrial DNA, PCR-RFLP INTRODUCTION Unambiguous species identification has become very important for two main reasons. Firstly, in order to expose the commercial frauds through species substitutions it was necessary to develop molecular methods to confirm the origin of different fish products from the market. This is an essential aspect, especially for high economical value species. For example, the sturgeons represent one of the most valuable natural resource. The sturgeon caviar is one of the most exclusive and expensive fishery products. The three mainly types of caviar: beluga, osietra and sevruga derived from Huso huso, Acipenser gueldenstaedtii and Acipenser stellatus differ through quality, availability and price and for these reasons they are often exposed to commercial falsification. Secondly, it is necessary to correctly identify these species in order to develop efficient management programs. The number of the sturgeon populations was severely decreased in the past century and their survival in the wild is seriously endangered. Under these circumstances, the restocking in natural basins with artificially reproduced fish may represent a reliable solution for stopping the extinction of the sturgeon species. If the sturgeon adults are easily to identify based on morphological characters, the correct identification of juveniles used in restocking programs is very difficult and imposes a reliable molecular method for this.