Abstract
As the global market for fisheries and aquaculture products expands, mislabeling of these products has become a growing concern in the food safety arena. Molecular species identification techniques hold the potential for rapid, accurate assessment of proper labeling. Here we developed and evaluated DNA barcodes for use in differentiating United States domestic and imported catfish species. First, we sequenced 651 base-pair barcodes from the cytochrome oxidase I (COI) gene from individuals of 9 species (and an Ictalurid hybrid) of domestic and imported catfish in accordance with standard DNA barcoding protocols. These included domestic Ictalurid catfish, and representative imported species from the families of Clariidae and Pangasiidae. Alignment of individual sequences from within a given species revealed highly consistent barcodes (98% similarity on average). These alignments allowed the development and analyses of consensus barcode sequences for each species and comparison with limited sequences in public databases (GenBank and Barcode of Life Data Systems). Validation tests carried out in blinded studies and with commercially purchased catfish samples (both frozen and fresh) revealed the reliability of DNA barcoding for differentiating between these catfish species. The developed protocols and consensus barcodes are valuable resources as increasing market and governmental scrutiny is placed on catfish and other fisheries and aquaculture products labeling in the United States.
Highlights
Catfish (Order Siluriformes) are a diverse group of fish representing more than 3,000 species, 478 genera and 36 families [1]
Our results indicate that DNA barcoding is a powerful technique, allowing accurate identification of known, blinded, and commercial samples
Barcode of Life Data Systems (BOLD)-IDS results were in agreement with GenBank results in identification of these species, yielding 100% identity, except for I. furcatus, P. bocourti and C. bouderius
Summary
Catfish (Order Siluriformes) are a diverse group of fish representing more than 3,000 species, 478 genera and 36 families [1]. Ictalurid catfish represent the largest segment of the domestic aquaculture industry in the United States, generating approximately 600 million pounds of catfish per year [2]. Imports of Pangasiid, Clariid, and Ictalurid catfish to the United States from East Asia (largely Vietnam and China) have increased rapidly over the last decade and account for up to half of catfish sales in the U.S [3]. New regulations currently under development by the federal government will seek to strengthen inspection of domestic and imported catfish, including verification of correct species labeling. Further development and validation of DNA barcoding techniques and consensus sequences for catfish are needed to ensure accuracy in product labeling and informed consumer choices
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