Significant differences were found between males and females in the fragmocone, external cone and widths of the cuttlebone in Sepia officinalis caught in the small-scale trap fishery off Gran Canaria Island (Spain). It is suggested that: (a) differences may depend on morphological adaptations of females for egg laying; (b) cuttlebones represent over 50% of the total cuttlefish caught (which is unrecorded in the fishery); and (c) the relationships between several morphometric measures of the cuttlebone and the mantle length and wet weight may allow more accurate biomass estimations of this species in the fishery.
