Jellyfish Lesions in Fish – Histopathology

Figure 5. Phialella quadrata attached to gill raker of Atlantic salmon and showing necrosis of epithelium, loss of basement membrane, and underlying dermal haemorrhage. A close inspection of the interface between the jellyfish and the gill epithelium shows tube-like extensions reaching down through the epithelium – nematocysts?

The negative interactions between jellyfish and fish in aquaculture appear to be an increasing problem. This is partly due to increased numbers of jellyfish, associated with global warming, reduced numbers of their predators, and to the intensification of aquaculture operations in many coastal areas worldwide. Most reported problems have occurred in marine-farmed salmonids in northwest Europe. Nevertheless, aquaculture operations in other regions such as Asia, North America, and Australia have also been affected. Jellyfish involved are primarily cnidarians i.e. those species with stinging cells –...