Reconstructing cephalopod migration with statolith elemental signatures: a case study using Dosidicus gigas

Cephalopods exhibit a variety of movement patterns during their lifespan, from the passive drifting of eggs and paralarvae to the active long-distance migrations of adults between feeding and spawning grounds. However, it is difficult to observe directly the movements of cephalopods at these different stages of development. An alternative approach is the use of elemental signatures recorded in statoliths to gain valuable insight into cephalopod movement. Dosidicus gigas is an economically important squid that undertakes large-scale migrations over its lifespan to satisfy its habitat requirements at different life history stages. In this study we used D. gigas as an example to illustrate a new approach to reconstructing cephalopod migration patterns using the relationship between sea surface temperature and elemental signature analyses of statoliths. We found that statolith elemental signatures are a useful natural tag to ascertain D. gigas migration routes from juvenile to adult stages. This approach is not applicable to embryonic and paralarval stages during which movement is more likely passive and determined by ocean currents. The conclusions which can be drawn from this study improve our knowledge of the distribution and migration of juvenile and adult cephalopods. Supplementary trophic analyses using stable isotopes would further benefit the reconstruction of cephalopod migration pathways.