Halibut pierced with mysterious ’projectile parasite’   

(ScienceNordic, 7 April 2012) -- The halibut is a popular delicacy among seafood lovers. But perhaps the pretty slices and the fine texture of this fish shouldn’t be taken for granted in the future. During filleting work, Greenlandic fishermen recently noticed that a specimen of Greenland halibut was full of strange cavities and holes that resemble shot wounds. The mysteriously infected fish was sent to the Laboratory of Aquatic Pathobiology at the University of Copenhagen, where researchers examined the holes in detail. They discovered that the Greenland halibut had been infected with a hitherto unknown parasite, which creates circular holes in the fish muscle. “At first glance it was impossible to see why the holes had appeared,” says Professor Kurt Buchmann, of the Laboratory of Aquatic Pathobiology at the Department of Veterinary Pathobiology at the University of Copenhagen, who headed the study. “But when I took a closer look through a microscope, I could see that the holes actually consisted of cartilage containing millions of tiny parasites of a previously unknown type. According to the professor, the holes emerged as a result of the parasites attacking cartilage elements in the fish’s skeleton. The cartilage reacts to the infection by swelling dramatically and transforming into long, circular cylinders that go straight through the fish’s musculature and make it appear riddled. ... The parasite has not been described before, neither by fish researchers nor parasite researchers. But its shape reveals that it is of the type Myxobulus – a parasite that’s characterised by being very small and rounded. Since Myxobulus hasn’t previously been observed in the halibut, the researchers knew they were dealing with a new species within Myxobulus. “Detailed DNA analyses also revealed that the newly-discovered projectile parasite was not present in the gene bank for parasites. Moreover, it differed greatly from other known types of parasites.” Although the projectile parasite has hitherto been completely unknown, it is not a newcomer. ”It has probably existed for millions of years – it’s just not been discovered by scientists until now.” Although the parasite makes the delicate fish flesh appear a bit less appetising, Buchmann stresses that it poses no threats to humans.

Posted 7 April 2012; 10:57:24 AM.   Permalink

Tagged: April12, Circumpolar News, Conservation and wildlife, Environment, Fisheries, Greenland