No. 12. GILPAT.pdf - Marine Institute Open Access Repository

NDP Marine Research Sub-Programme 2007-2013Table 2.4: Summary data of the numbers and regional distribution of the seventeen studypopulations.Species North West Mid West South West TotalAtlantic salmon 821,920 3,379,724 1,107,920 5,308,934Rainbow trout 100,000 200,000 120,000 420,000Atlantic cod - 40,000 - 40,000Total 921,920 3,619,724 1,227,920 5,768,934The overall mortality to gill disorder for the seventeen sites combined was 13.0%. Ten of thethirteen Atlantic salmon populations were affected by gill disorder and one of the threerainbow trout sites. In the affected Atlantic salmon populations mortality ranged from 8% to54%. Affected fish presented with similar pathologies at all sites: multifocal hyperplasia; fusion;and necrosis of the gills. The progression of the condition was broadly similar on all affectedfarms, characterised by a rapid rise in mortalities shortly after the initial occurrence. Table 2.5presents summary data for the percentage mortality, relative to the input number, for thethree regions and three species.Table 2.5: Summary data showing percentage mortality to gill disorder (as a % of input number) foreach of the species in the different regions.Species North West Mid West South West TotalAtlantic salmon 0% 17.5% 13.8% 14%Rainbow trout 0% 0% 5% 1.4%Atlantic cod - 0% - 0%Total 0% 16.3% 13% 13%2.2.4. Results by variable (Atlantic Salmon)Regional LocationThere were 821,920 salmon in one site in the north west region, 3,379,724 salmon in ninesites in the mid west, and 1,107,920 salmon in three sites in the south west. The meanpercentage mortality to gill disorder of the population in the north west was zero, the midwest was 20.7% (SD±14.5), and the south west was 18.0% (SD±31.2). There was no significantdifference in gill disorder mortalities between the mid west and south west regions (P=0.90).14