A method is described for the non-destructive, non-invasive, detection of shell lesions in the New Zealand paua, a marine gastropod Haliotis iris using diagnostic radiology. The X-ray method reliably detected the presence of shell lesions in 96% of the cases examined once lesion dimensions exceeded 6.2 × 7.1 mm. The extent of lesions above this size can be reliably and accurately determined from X-ray images viewed on a video display unit (VDU). Biofouling on the outside of the shell can cause misdiagnoses. This method is a significant animal welfare refinement in the identification of marine gastropods with shell lesions, when compared with traditional techniques which kill the animals.