<p>In the Hudson Bay system, changes in the diets of seabirds and seals over the past four decades suggested a gradual displacement of polar cod (<i>Boreogadus saida</i>) by capelin (<i>Mallotus villosus</i>) and to a lesser extent by sand lance (<i>Ammodytes</i> spp.). However, this hypothetical borealization can only be inferred due to the lack of recent data on abundance and distribution of fish in the region. In this study, we combined age-0 fish samples from various expeditions, forming the most extensive fish dataset in the region to date, and laying down baseline information about distribution and abundances of fish species within the Hudson Bay system. The fish larvae assemblages indicate that there are three key age-0 fish larvae species in the Hudson Bay system; polar cod, capelin, and sand lance. Capelin larvae were by far the most abundant overall (maximum of 5841 individuals 1000&#xa0;m⁻³), but assemblages containing polar cod were more widespread across the region and had little geographical overlap with capelin. Polar cod larvae were on average 20&#xa0;mm larger than capelin larvae, suggesting different prey size spectra and thus little food competition. However, polar cod larvae overlapped temporally, geographically, and in size with northern sand lance (<i>Ammodytes dubius</i>) larvae. We conclude that the co-distribution of ichthyoplankton species in the Hudson Bay system shows no conclusive evidence that capelin have completely displaced polar cod in this region yet.</p>