DO probes are contained within every Tassal pen, continuously feeding information back to a centralised feed barge. A fish not only requires additional oxygen whilst burst swimming for feed, it also utilises oxygen in metabolic processes post-feeding. It is for this reason that minimum DO limits are set for feeding and if exceeded, feeding is ceased until DO rises to an acceptable level. This aims to reduce stress on stock, reduce oxygen consumption and mitigate against potential mortalities due to insufficient DO. There is also a greater focus on DO probe calibration to ensure accuracy of readings.