Information on fish kills have been compiled and reported annually since 1969 by the Inland Fisheries Trust (formerly the Central and Regional Fisheries Boards and now Inland Fisheries Ireland) and Marine Institute (formerly Fisheries Research Centre). The authors collated all available data from published annual reports, fish kills reports and internal unpublished IFI reports. The data used varied in quality throughout the period with no, or sparse records available during certain periods in the 1970’s, 1980’s and 1990’s.  Information on the species impacted and the number of mortalities was typically reported to the relevant agencies or gathered by those assessing the fish kills in response to these reports. This data was collated and summarised into four categories, i.e., salmonid, coarse fish, marine and other fish. In a small number (approximately 20) of cases “All species” was reported, we assigned these cases to salmonids as no other information was available.   The cause of most fish kill events was recorded at the time of the incident but in many cases, the reason was unreported because the cause was unknown, or suspected but unconfirmed. In addition, many records were described with varying degrees of detail rather than assigned to convenient and discrete categories. In other instances, more than one cause was described. Where data were available the specific cause was classified into eight broad categories, namely agriculture, construction, eutrophication, industrial, mining, municipal, other and unknown.  Where a fish kill impacted both a river and a lake, the data was treated as two separate incidents and assigned separate codes, but such instances were rare. Where a fish kill impacted both a tributary and a main channel, the data was treated as one incident.  The data lags at least a year behind IFI’s internal reports to allow for prosecutions to be completed.  Link to report - Fish and Habitats: Science and Management, Vol. 3 Fish Kills in Ireland – History, Current Status and Recovery  REST (JSON)