First record of Tetramicra brevifilum in lumpfish (Cyclopterus lumpus, L.)

Abstract

A microsporidian species with 98.3-98.4% nucleotide identity to Tetramicra brevifilum (Journal of Fish Diseases, 3, 1980, 495) was diagnosed in lumpfish (Cyclopterus lumpus, L.) broodstock held at a breeding and rearing facility in western Ireland. The fish were wild-caught from the west coast of Ireland, and the first case was diagnosed one year after capture. Clinical signs included severe bloating, lethargy, exophthalmos, anorexia, white patches on the cornea and externally visible parasitic cysts on skin and fins. Necropsy revealed severe ascites, white nodules and vacuoles in all the internal organs and partial liquefaction of the skeletal muscle. On histological examination, microsporidian xenomas were observed in all internal organs, the skin, skeletal muscle, gills and the eyes. The microsporidian species was identified by molecular analysis and transmission electron microscopy. This is the first record of T. brevifilum infecting lumpfish, and the disease is considered to be of potential significance to the rising aquaculture industry of this species.

Lumpfish (Cyclopterus lumpus, Linnaeus) is susceptible to viral nervous necrosis: Result of an experimental infection with different genotypes of Betanodavirus

“…New diseases and infectious agents inevitably emerge when new species are introduced to aquaculture, and the lumpfish appears to pose no exception to this rule. A range of different pathogens has been detected in wild and farmed lumpfish, including viruses, bacteria, parasites and fungi (Alarcón, Gulla, et al, 2016;Alarcón, Thoen, et al, 2016;Guðmundsdóttir et al, 2019;Hjeltnes, 2014;Johansen, 2013;Marcos-López, Donald, Stagg, & McCarthy, 2013;Poppe et al, 2012;Scholz et al, 2017;Scholz, Ruane, Marcos-Lopez, et al, 2018;Skoge, Brattespe, Økland, Plarre, & Nylund, 2018;Stagg et al, 2017;Treasurer & Birkbeck, 2018). Finally, the possible role of cleaner fish as subclinical carrier for viral disease has emerged (Rimstad Basic, Gulla, & Hjeltnes & Mortensen, 2017).…”

Cleaner fish diseases

“…Evidence supporting this concern is found within the case report by Scholz et al. () describing the detection of the microsporidiosis caused by Tetramicra brevilfilum in lumpfish. They point out the concerns associated with this agent relative to the rise of cleaner fish aquaculture.…”

“…Biosecurity concerns are also raised by the findings of Scholz et al. () through their detection of Piscine myocarditis virus (the virus responsible for cardiomyopathy syndrome—CMS) within two species of wild‐caught wrasse being used for sea lice control on salmon farms in Ireland. A paper by Røsӕg et al.…”

An overview of cleaner fish use in Ireland

“…comm.). Some of the diseases noted in the hatchery (Ireland) at ambient water temperatures include AGD, piscirickettsia (Marcos‐Lόpez et al ., ) and microsporidia (Scholz et al ., ). There are currently no registered vaccines in Ireland for lumpsucker; an autogenous vaccine is being developed for use and will be available by the end of 2017.…”

“…Lumpsucker juveniles were produced from eggs of various origins including the UK, Norway and native Irish stocks (natural spawning in hatchery on‐grown adults and wild egg masses found on the shore). Some problems associated with culture have included tail nipping and disease outbreaks in juveniles (e.g., Marcos‐Lόpez et al ., ) and broodstock (e.g., Scholz et al ., ). These have been mitigated to a large extent through a variety of measures including alterations to feeding regime and husbandry practices.…”