The landing obligation is a key element of the reform to the Common Fisheries Policy (CFP) which came into force on 1st January 2014. Other key changes include regionalised fisheries management and a legal commitment to fish sustainably. A ban on discarding comes into force for pelagic fisheries first, on 1st January 2015. Subsequently, it will cover demersal fisheries between 2016 and 2019. It only applies to fish stocks which are managed by catch limits, or quotas. Non-quota stocks are not covered by the discard ban. The landing obligation, often referred to as the discard ban, is a ban on discarding fish which are subject to catch limits, so that all catches must be brought ashore, except where they are subject to specific exemptions. This means that quotas now control what is caught at sea, rather than what is landed onshore. Article 14 of the new CFP basic regulation stipulates that “Member States may produce a “discard atlas” showing the level of discards in each of the fisheries covered by the landing obligation”. For the North Sea, the ‘Scheveningen Group’ developed a discard atlas to document the current knowledge of how much discards are generated in the North Sea and to assemble information on strategies to mitigate discards. This latest report presents an analogous document, following the format of the North Sea work, to produce a discards atlas for the North Western Waters (NWW) region – specifically, for demersal fisheries. The principle of the landing obligation is to provide a limit on total catch, whereby all catches of regulated species are landed, and once any of the quotas in a fishery are reached, fishing activities cease on species whose quotas are exhausted. It is anticipated this will motivate changes in fishing behaviour and practices. To maximize revenue from their catch, fishermen will attempt to avoid catching fish that will result in a curtailment of the fishing season (sometimes referred to as ‘choke species’) and avoid catching undersized, and low-value fish, which would be deducted from their quota for little or no profit. The level of incentive, and the potential impact for vessel operators, will be dependent on their catch and discard patterns and the quota availability. The purpose of this discard atlas is to provide evidence of discard patterns for different fishing fleets in the North Western Waters region. This information may be used to assist regional managers with the identification of fisheries which may need more focussed attention in the transition to the landing obligation, and in the formulation of a Discard Plan and Multi-Annual Plans (MAPs). There is substantial detail presented in this atlas. The NWW Atlas is intended to be interrogated by regional managers to enable comparisons between fishing vessel groups (fleet segments), fisheries and species, and in turn facilitate priority setting. It is not the intention of the atlas to articulate different management options; hence there is limited analysis and discussion of the content. With this purpose in mind, it is important to understand the quality of the data. The NWW Atlas is derived from the best available data. The results presented are based on the official STECF database which holds information on landings and discards between 2003 and 2012. The information on effort,landings and discards in EU fisheries are derived from two sources - effort and landings from the national fisheries statistics, and discards data collected under the EU Data Collection Framework (DCF, EEC, 2000). Discard data are sampled and recorded for less than 2% of all fishing operations, and these data are extrapolated to the fleet level. Where no data exist for a fishery, fill-ins are used from data from related fisheries, as is standard practice. If an estimate is largely derived from such filled-in data it may be less accurate. As with the North Sea atlas, the data quality of discard estimates was assessed by calculating the proportion of the discard estimate derived from actual observations relative to the overall amount of discards. However, this does not account for the level of initial extrapolation from the samples to the fleet, which can mean estimates are based on low samples. Known uncertainties in the data are described in the text that support the tables. The STECF database was used to compile landings and discards data for some of the most-commonly caught species in the North Western Waters (STECF 2013a) using data from 2010 to 2012. The data presented are from the west of Scotland (VIa), Irish Sea (VIIa) and the Celtic Sea (ICES Divisions VII b-c and e-k). The data for the Eastern Channel (VIId) was compiled for the Discard Atlas of North Sea Fisheries and can be found in Annex 8. Discard ratios were used to express the percentage proportion of the catch that consisted of discards. Data are presented in the same format as that in the ‘Discard Atlas of North Sea Fisheries’ - estimated totals of landings and discards (in tonnes) by year and species, country and fisheries. The analysis of the pelagic fisheries was conducted prior to, and separately from, the demersal fisheries. The ‘Discard Atlas of the North Western Waters Pelagic and Industrial Fisheries’ can be found here. Included within the NWW Discard Atlas is a review of some of the legislation introduced and research conducted to mitigate discards. To improve mitigation strategies, it is important to know the reasons for discarding. Unfortunately, precise reasons are often unknown, because they are not recorded by fishers, and also because a mix of market- and regulatory conditions may influence decisions to discard. Inferences on the drivers for discarding can be made based on the length of the fish and the presence of different regulations. This is further elaborated upon in the ‘Discard Atlas of North Sea Fisheries’ which can be found here. The various reasons for discarding will necessitate different solutions. It should be understood that the methods most effective at mitigating discards of larger fish, driven by quota restrictions, will be different to discards that are undersized and are driven by the selective properties of fishing gears. Therefore, the data presented here should be used as a start point to identify fisheries which require more attention in the implementation of the CFP. More detailed analysis of the discard patterns in these fisheries is then required to determine appropriate mitigation and management strategies. It should also be noted that historical discard patterns (2010-12) indicate the potential issues under the future landing obligation, but pulses in recruitment or changing distributions of species may create different issues for fishing vessel operators than those that can be deduced from the historical data presented here.