First record of cuticle bands in the stomach ossicles of the red king crab Paralithodes camtschaticus (Tilesius, 1815) (Decapoda: Anomura: Lithodidae) from Norway.

The red king crab Paralithodes camtschaticus (Tilesius, 1815) is a large predator intentionally introduced to the Barents Sea and adjacent fjords in the 1960s. Its establishment has given rise to both a high-value fishery and destructive effects on seafloor habitats and communities. Given the need for accurate information on age, growth, and longevity that could improve management and mitigation strategies for red king crab, developing and testing new aging methods for this and other crustaceans has been an active field of research. We contribute to this test bed by investigating cuticle bands in gastric mill ossicles of male and female red king crabs. Cuticle bands were detectable in most individuals studied and maximum cuticle band count was 13 for males (N = 62, 38–180 mm carapace length (CL)) and 9 for females (N = 34, size range 80–147 mm CL). There was large variation of size-at-band count and band count-at-size data. The number of cuticle bands generally increased with CL in male red king crabs; low sample size and small size range in females prevented seeing any trend. Exploring calcein staining in a sub-sample of the crabs suggested uptake of the stain, yet without a clearly defined mark, and showed deposition of ossicular material beyond the calcein stain in the subsequent year. We recommend research on the mechanism generating band deposition to shed light on how and when bands are formed as the basis for testing whether the cuticle bands may reflect chronological (specifically annual) age. Specifically, we recommend long-term maintenance of crabs, study of both moults and newly formed ossicle structures, as well as stringent testing of band periodicity with known-age crabs, including all size classes and both sexes.acceptedVersio