Developing a zooplankton infection trial for Atlantic salmon

Gill disease is one of the most significant health threats to salmonid culture in the marine environment. Most forms of gill disease are multifactorial, and micro jellyfish are thought to play an important role in disease development. Cnidarian micro jellyfish can cause insults to the gills, impeding fish respiration. This can lead to reduced productivity, poor fish welfare and, in some instances, death. The lack of scientific and technical understanding of the interactions between micro jellyfish and fish gills is a significant knowledge gap. Obtaining this knowledge from field studies is challenging because it is unknown when or where a certain species of harmful micro jellyfish will occur or in what quantities, making it impossible to challenge fish consistently and repeatedly with micro jellyfish to observe and study their interactions and the effects on gills. Furthermore, micro jellyfish may carry fish pathogens, biasing the outcome of gill damage observed. This feasibility study aims to develop a lab-based challenge model, using lab-reared micro jellyfish to assess the damage they cause to fish gills after a challenge. This innovative challenge model, once established, will be a starting point for addressing multiple other aspects of gill disease. It would open the door to research not currently possible, including but not limited to improvements of our understanding of multifactorial interactions associated with gill disease, development of treatments and testing of functional feeds.