Fish ’n chips: ZooMS peptide mass fingerprinting in a 96 well plate format to identify fish bone fragments

Fish are a large, highly diverse, and anthropologically important group of vertebrates. However, fish bones are underrepresented in the archaeological literature because they are less stable than those of other taxa and identification of bone to species is often difficult or impossible. We explore a new identification system, ZooMS (Zooarchaeology by Mass Spectrometry), which is based upon protein barcoding. As proteins can be cleaved enzymatically and analyzed by mass spectrometry in a repeatable way, protein barcoding is used widely in microbiological contexts for quick and inexpensive protein identification; mass spectra reflect the differences in protein sequence and can therefore be reproducibly linked to a particular protein or protein fragment. ZooMS uses peptide fingerprinting of bone collagen as a method for rapid identification of archaeological bone. This has involved the identification of masses related to peptides of known sequence. For mammals, sufficient sequence information is available for this approach but for groups, such the teleost fish, species are highly diverse and there are few available collagen sequences. Here we report a preliminary investigation into the identification of fish species by peptide mass fingerprinting that does not require sequence information. Collagen mass spectra are used to identify eight species of bony fishes (Osteichthyes) from four orders: Clupeiformes, Salmoniformes, Gadiformes, and Perciformes. The method is applied to both modern and archaeological fish remains and offers the capacity to identify traditionally unidentifiable fish fragments, thus increasing the Number of Identified Specimens (NISP) and providing invaluable information in specialized contexts.

► We explore an identification system for fish bones, based upon protein barcoding. ► The system uses a database of collagen spectra, but not sequence information. ► The method correctly identified modern and archaeological bones from eight species. ► Confidence scores helped distinguish when bones were from species not in the database. ► The method could help increase information gained from fragmented fish bones.