Abstract
The notothenid Patagonotothen ramsayi is one of the most abundant fin fish species on the Patagonian Shelf and it is an important prey species and central to the trophic ecology of the shelf ecosystem of the region. 353 otoliths and the parasites analysed from 80 fishes collected in January 2010, and 2004 and 2006, respectively, from the Falkland Islands Shelf and in an area north of the Falkland Islands on the high seas, were used to gain insights into the stock discrimination using elemental signatures and parasitology. Multivariate analyses (Quadratic Discriminant Function Analysis (QDFA)) of trace elements in the edges of the otolith was extremely well resolved indicating samples taken from the southern (SS), northern Falkland Islands shelf (NS) and the high seas (HS) to the north are clearly separated. Analyses of the otoliths cores were less well resolved, but showed good separation. However, there was overlap with the samples taken on the SS / NS, NS / HS, but no overlap between the samples taken on the SS / HS, indicating some intermixing during larval dispersal. Univariate and multivariate analyses of parasite communities showed a clear separation of samples taken from the SS and HS. In addition, this study has added to the biogeography and knowledge of host specificity of the parasites inhabiting the Patagonian Shelf. Our results demonstrate that the multi-pronged approach of using both otolith trace elemental analyses and parasites can be a powerful tool to resolve stock discrimination in P. ramsayi.