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The viability of stable isotopic carbon (δ[sup.13]C) and nitrogen (δ[sup.15]N) signatures to track the exchange of sea lice, Lepeophtheirus salmonis, between hosts was tested. It was predicted that nonfeeding sea lice would experience lowered δ[sup.13]C signatures and enriched δ[sup.15]N signatures owing, at least in part, to moulting during development. It was also predicted that newly settled parasitic first generation sea lice (late stage copepodids) would retain isotopic signatures indistinguishable from their natal host fish population. During this laboratory study, δ[sup.13]C signatures of nonfeeding sea lice developmental stages declined over time, while the δ[sup.13]C signature of chalimus III sea lice was not significantly different from fin and gill signatures of their natal hosts, thus providing an isotopic link to their natal host fish population. In contrast, δ[sup.15]N analysis did not show promise as a tracer in this study, as host fish populations did not display distinct δ[sup.15]N signatures. These results suggest that δ[sup.13]C signatures may be applied to identify sources of sea lice epizootics and potentially quantify the exchange of sea lice between cultured and wild salmon populations. Nous evaluons l'utilisation des signatures d'isotopes stables de carbone (δ[sup.13]C) et d'azote (δ[sup.15]N) pour suivre les echanges de poux de mer, Lepeophtheirus salmonis, entre les hotes. Nous predisons que les poux de mer qui ne s'alimentent pas ont des signatures δ[sup.13]C reduites et des signatures δ[sup.15]N enrichies a cause, au moins en partie, de la mue durant le developpement et que les poux de mer parasites de premiere generation recemment fixes (copepodites de derniers stades) retiennent des signatures isotopiques impossibles a distinguer de celles de leur population natale de poissons hotes. Dans notre etude en laboratoire, les signatures δ[sup.13]C des stades de developpement des poux de mer qui ne se nourrissent pas decroissent dans le temps, alors que les signatures δ[sup.13]C des poux de mer de stade chalimus III ne different pas significativement des signatures des nageoires et des branchies de leur hote natal, ce qui fournit ainsi un lien isotopique avec leur population natale de poissons hotes. En revanche, l'analyse des δ[sup.15]Nnes'avere pas prometteuse comme traceur dans notre etude puisque les populations de poissons hotes ne possedent pas de signatures δ[sup.15]N distinctes. Ces resultats font croire que les signatures δ[sup.13]C peuvent etre utilisees pour identifier les sources d'epizooties a poux de mer et potentiellement pour mesurer les echanges de poux de mer entre les populations sauvages et cultivees de saumons. [Traduit par la Redaction], Introduction The sea louse, Lepeophtheirus salmonis, is an ectoparasitic, caligid copepod commonly found on both farmed and wild salmon in the Northern Hemisphere (Kabata 1988). The life history of this [...]