| Summary: | Fisheries around the world have a substantial impact on marine ecosystems through the removal of biomass and modification of habitats, which alters the conditions within food webs. However, our understanding of this impact and consequences for the ecosystems is limited. Despite this limitation and uncertainty, fisheries have been allowed to develop and expand, causing substantial reductions in many fish stocks due to overfishing. The main reason for stock depletion is overcapacity (leading to non-sustainable fishing effort and catches), which has been largely fueled by government subsidies to fisheries. The Baltic Sea is no exception, high fishing pressure combined with unfavorable conditions for the reproduction of Atlantic cod (Gadus morhua), the historically dominant large predatory fish, resulted in a rapidly decrease of annual landings in the late 1980s, from which cod stocks have not recovered. More recently, landings are dominated by small pelagic species, herring (Clupea harengus), and sprat (Sprattus sprattus), whose high exploitation of the ecosystem can have significant negative consequences for the processes within it. There are several components of fisheries catches that are usually not accounted for and hence not reported, and these are Illegal, Unregulated, and Unreported (IUU) catches. With the hope to contribute to a better understanding of total fisheries impacts and improved management leading to sustainable catch levels, a catch data reconstruction for Swedish fisheries in the Baltic Sea, from 1950-2007, was undertaken. The catch reconstruction estimated IUU catches, including discards, and recreational catches, and added those to a foundation based on the officially reported landings as presented by the International Council for Exploration of the Sea (ICES) on behalf of Swedish government. Data and information on unreported landings were sparse, and much of the estimations had to be based on interpolation between ‘anchor points’, which in turn were formed using an assumption-based approach ...
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