For health auditing purposes, a farm is considered active once three pens of fish have been present for 30 days, following entry of the first pen of fish at the farm. Fisheries and Oceans Canada (DFO) applies a computerized selection system to randomly select active salmon farms within the fish health zones of the British Columbia. coast. All farms within a zone are assigned a random number and a computer selection of the farms within that zone is weighted (based on the fish species and the number of “active farms” operating in that zone as a percentage of the total number of active farms in the province). In other words, if a zone contains 30 percent of the farms then 30 percent of the farms selected for audit would be randomly chosen from that area. This ensures equal probability of each farm being selected for sampling. To ensure confidence in the sample results, Fisheries and Oceans Canada endeavours to conduct fish health audits at 30 active farmsites per quarter, or approximately 120 each year. Farm audits are conducted in conjunction with the farm’s regularly scheduled carcass collection, allowing Fisheries and Oceans Canada staff access to the freshest of the dead fish. This approach of targeted disease sampling on recently dead fish increases the likelihood of DFO veterinarians finding disease, if present, and attributing an accurate “cause-of-death” diagnosis to each carcass gathered. The summary tables are updated quarterly to reflect Fisheries and Oceans Canada’s fish health monitoring activities. For the purpose of fish health monitoring, a site is considered “active” if the facility holds any salmonid for at least 30 days, and has a minimum of three fully stocked pens during the quarter in which sampling is to occur.