Fish farm health evaluation: interpretation of site mortality records

• Main Author: Soares, Silvia
• Other Authors: Green, Darren, Crumlish, Margaret, Murray, Alexander, University of Stirling and Marine Scotland Science, School of Applied Social Science, Aquaculture
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: University of Stirling 2012
• Subjects: Mortality records; Database; Surveillance; Fish health; Fish-culture; Fish Diseases; Atlantic salmon
• Online Access: http://hdl.handle.net/1893/9268; http://dspace.stir.ac.uk/bitstream/1893/9268/1/Thesis_Sil.pdf

In aquaculture worldwide, diseases are a significant constraint to economic expansion. The Scottish salmonid industry has experienced many cycles of development, with episodes of little or negative profitability caused by excess of production, and times of crisis due to different disease problems. In Scotland, the early implementation of regulation largely contributed to the control of infectious disease outbreaks. The recent Chilean outbreak of infectious salmon anaemia (ISA) illustrated the threats and the impacts of disease in the aquaculture industry and the importance of implementing good regulation and husbandry practices to reduce the impact of the spread of infectious disease. Databases of site production data have an important role to play in the investigation and understanding of diseases. They store valuable data collected during the time of production, which are essential for the identification of potential health and production problems during the production cycle of farmed fish. Mortality records are one of the most important sources of information on a farm, especially if it includes the cause of death as deformities, predators and diseases. Any deviation from the expected levels of mortality may indicate production problems, infectious diseases, or inadequate welfare. The investigation of increased rates of mortality must include examining farm records, determining the influence of death rate on production and the potential risk factors of diseases in a farm. This project demonstrated the importance of mortality records for setting industry standards of “expected” mortality losses and for investigating the value of recorded mortalities as a tool for aiding in surveillance and control of infectious diseases. It also aimed to determine the utility of reported mortality in supporting and assisting management-strategy decisions at the farm and industry level. In this project, we developed a baseline benchmark curve for expected mortality losses for Atlantic salmon in seawater. This novel approach ...