For any exploited fish population, like the black-spotted croaker, studies on the dynamics of the population need to begin with determining the biological identity of the species in relation to neighbouring populations of the same species. Parasites represent ideal indicators of host population variance and movements, and the present study has utilised the parasite assemblages affecting the black-spotted croaker as biological tags to understand the basic biology and population structure of the fish. Given the predicted consequences of climate changes on marine species richness and ecosystem functionality, the aim of this presentation was to also review the potential environmental impacts on the marine parasite-host systems. Complex analysis using the parasites as biological tags confirmed the presence of four distinct fish populations off the northern Australian study area. In addition to deciphering the stock structure of this important fish, multivariate analysis provided significant insight into both the direct climate-induced pressures placed on the sciaenid, and the indirect influences of climate on the marine ecosystem. The sciaenid demonstrated small scale movements and behaviour alterations depending on the spatial and temporal measures of the study, with environmental changes confirming the potential influence of future climate changes on the survivability of the large teleost and its parasites. It is with accelerated importance that biological studies on important marine species such as the sciaenid are done, and with the results from this study highlighting the seasonality impacts on parasite-host systems, there is no doubt that parasitic organisms represent an integral role in future fish biology and climate studies.