SupplementaryMaterial_IndividualAngelShark

There is a growing call to restore the natural richness of the North Sea, but it is often unclear what this natural richness actually was. Here we review the demise and the historical ecology of an iconic species, the critically endangered Angelshark Squatina squatina in the southern North Sea, using historical books and catch records of 104 individuals brought to the Dutch fish markets. These sources reveal that between 1600 and 1950, Angelsharks were annual visitors to the North Sea, and in some years were fairly commonly observed. The number of recorded individuals peaked in the early 20th century and between 1945-1955, and declining rapidly in the 1960s, with the last recorded observation in 1973. The decline coincides with the introduction of engine-powered fisheries, whereas the full extirpation followed the increased use of diesel-powered beam-trawlers. The recorded observations of Angelsharks were most commonly from the summer season, in accordance with the prevailing notion of Angelsharks migrating to warmer waters in winter. Furthermore, most recorded catches were of newborns and adult females in shallow waters, showcasing the importance of the area for parturition and nursery. Our review exemplifies how a large predator disappeared from a marine food web and shows the importance of historical data to deduce the natural richness of the North Sea.