Gill disorders in marine-farmed salmon: ­investigating the role of hydrozoan jellyfish

摘要: Jellyfish have been implicitly linked to a number of fish kill events in marine-farmed fin- over recent decades. However, due insufficient data, it is difficult identify small hydrozoan jellyfish as the causative agents more common and chronic problem gill disorders. Gill dis- orders (physical, pathogenic or parasitic damage gills) can be caused by water- borne are an increasing though poorly understood for aquaculture industry. Hence, first year-long monitoring programme study jellyfish, other gelatinous zoo- plankton, phytoplankton health was initiated at 2 sites on west coast Ire- land. At southern site, species previously implicated (Muggiaea atlantica Solmaris corona) occurred high abundances (combined density ~450 m -3 , order magnitude lower than during previous mass mortality events). The this site exhibited clinically significant throughout peak abundance. Analyses revealed positive correlation between daily abundance these but not with any factors. northern there were low jellyfish; nevertheless, protozoan parasite Trichodina sp. observed shorter time period. As European sector experiences annual economic losses disorders, findings raise concerns expected growth industry, especially populations predicted increase some areas. Therefore, mitigation methods need developed implemented.