To identify the species of an unknown sample using its DNA sequence, we must have a database of reference sequences from known species for comparison. Molecular geneticists have access to public DNA sequence databases like Genbank, but forensic casework cannot depend upon them entirely as these resources often lack verification and critical sample information. To fill the need for reliable sequence data for species identification, we have created a forensic voucher collection for marine fishes
A ‘voucher specimen’ is an individual that is retained as a reference in a permanent collection and serves as a basis of study. Because we are using DNA sequences for taxonomic identification in the absence of traditional morphological characters, it is important that our DNA reference data are linked to samples that have been identified by taxonomic experts. All of the DNA sequences in our species database are generated from the voucher specimens archived in our collection. Whole bodies, with taxonomically relevant characters intact, are available for examination and re-verification if necessary.
Center geneticists are working with the University of Washington to continue to grow our voucher collection of fishes from the Northeastern Pacific Ocean (currently containing over 600 specimens focusing on rockfish and other commercially-important groundfish). The vouchers enable us to identify, with confidence, unknown samples for NOAA Fisheries Office of Law Enforcement casework.
The steps involved in compiling the collection:
While a molecular genetic baseline of marine fishes is an important tool for future forensic application needs, it also contributes to cooperative research with other disciplines that assess marine stock abundance and recruitment.
The forensic marine voucher collection also interfaces with the Barcode of Life Databases. This database uses a standardized DNA marker for all species on the planet. The DNA sequences in the The Fish Barcode of Life Initiative (FISH-BOL)are confirmed reference material and can often be used for forensic DNA analysis.