First report of(Monopisthocotyla: Gyrodactylidae) on farmed rainbow trout(Walbaum, 1792) in Russia.

Abstract

We recordedLautraite, Blanc, Thiery, Daniel & Vigneulle, 1999 on one-year-old farmed rainbow trout(Salmoniformes, Salmonidae) from Lake Kalmozero (White Sea drainage system, Republic of Karelia, Russia) in May and October 2023. Morphological identification of these specimens was confirmed by molecular data on the mitochondrial cytochromeoxidase subunit 1 () gene and the ribosomal internal transcribed spacer 2 (). Analyses of the newly obtainedgene sequences show they are identical to fragments of sequences of this gene forindividuals collected from wildin Slovenia and from farmedin Russia. Sequencing of theregion revealed ribotype D found previously in wildandin Austria, and in farmedandin Poland. The infection prevalences in the caged rainbow trout were 100% and 75%, and the mean abundances were 20.8 and 18.1 ind., in May and October, respectively. There were no significant differences between the parasite abundance distributions in these two months, likely indicating similar levels of resistance to the infection. This is the first report onfrom the White Sea drainage basin as well as in farmed rainbow trout in Russia. This new finding is a signal for veterinary authorities to strengthen parasitological monitoring of transported stocking material.