Genetic Structure of Juvenile Stages of Phocanema bulbosum (Nematoda, Chromadorea: Anisakidae) Parasitizing Commercial Fish, Atlantic Cod Gadus morhua, and American Plaice Hippoglossoides platessoides in the Barents Sea

Atlantic cod Gadus morhua and American plaice Hippoglossoides platessoides are two of the most commercially valuable species in the Barents Sea (FAO Area 27). They are considered as an important but neglected source of zoonotic risk associated with nematodes from the genus Phocanema. The abundance of Phocanema spp. in a fish host individual in the Barents Sea may be quite high, which is convenient for studying the genetic structure of its populations. A total of 69 third-stage juveniles of Phocanema spp. were isolated from the liver, the mesentery, and the musculature of G. morhua and H. platessoides and genotyped by the mtDNA Cox2 gene. Almost all these juveniles (68) were molecularly identified as P. bulbosum. The mtDNA Cox2 gene was also used to reveal the haplotype diversity and the genetic structure of P. bulbosum. A comparison of the specimens examined in this study with each other and with the haplotypes previously identified by us in the White Sea showed that there were no significant differences between the groups from different hosts and from different catch areas.

Automated summary

Atlantic cod and American plaice are commercially valuable species in the Barents Sea and are found to carry the nematodes from the Phocanema genus. The high abundance of Phocanema in these fish provides a convenient opportunity to study the genetic structure of these populations. Genetic analysis revealed that most of the isolated juveniles belonged to the species P. bulbosum. Furthermore, there were no significant differences found between the groups from different hosts and catch areas.