The starry smooth-hound (Mustelus asterias) is a small elasmobranch found in the Northeast Atlantic. Little is known about its environmental drivers and the threats it may be facing under current fishing practices. This thesis focused on assessing how environmental factors affect smooth-hound distribution, its ecology and mortality due to fishing in northern European shelf seas. A species distribution model revealed starry smooth-hounds occur in highest densities in the English Channel, southern North Sea and Celtic and Irish Seas, in sea surface temperatures between 5°C and 10°C and depths between 0 and 160 m. Distance to coast did not affect their distribution. Analysis of stomach contents indicated that they feed predominantly on crustaceans. Trophic ecology was also investigated with a stable isotope analysis and revealed size, depth, longitude and season were drivers of their feeding habits. On the west of Scotland, isotopic signatures suggested larger individuals fed in different areas and at higher trophic levels than juveniles, indicating potential seasonal migration of adults. In the North Sea, however, nitrogen isotopic signatures did not suggest that adults fed at higher trophic levels. Both populations showed isotopic signatures suggesting seasonal sexual segregation. Discard mortality within northern EU waters was estimated to be higher than fishing mortality that has been shown to be consistent with sustaining populations of elasmobranchs. Discards by French fishing fleets were ten times higher than those of Scottish fleets, with discard mortalities of 0.139 and 0.012, respectively. Discards were highest in the English Channel and the Celtic Sea. Comparison with discard mortality of other elasmobranchs showed variation depending on the distribution of each species. Theses results indicate that smooth-hounds are under threat from discarding in areas where they are more prevalent. If these species are to be protected, mitigation may be required in the form of, for example, spatial management.