Cod (Gadus morhua) and haddock (Melanogrammus aeglefinus) are the two dominant fish species in terms of biomass in the Barents Sea and as juveniles they have a similar diet. Cod grow larger than haddock and become more piscivorous with size. In contrast adult haddock feed mainly on benthic invertebrates. The cod and haddock stocks inhabiting the Barents Sea are the largest stocks of these demersal fish species world-wide. On the Scotian Shelf there are four separately managed stocks of cod and haddock and those located on the eastern half of the shelf collapsed during the early 1990s with limited recovery to date (Frank et al 2005). This in contrast to the Barents Sea where cod and haddock has increased greatly from the mid 2000’s (ICES 2019) (Johansen et al 2013, Landa et al 2014, Fall et al 2018, Johannesen et al 2020). This contrast between the two ecosystems will help in understanding key processes determining the spatial ecology of cod and haddock in the Barents Sea. The spatial extent of Barents Sea cod and haddock distributions increase with stock size (Landa et al 2014, Fall et al 2018). Similar patterns have been found for the Scotian Shelf cod and haddock stocks (Fisher and Frank 2004). Stock sizes for both are in turn determined by oceanographic conditions and the availability of plankton prey at early life stages (recruitment), individual growth and fishing pressure. Therefore, the drivers of cod and haddock spatial distributions and their impact on other species in the ecosystem should both differ and share some similarities that could provide meaningful insights regarding the interactions between the two species and how variation in fishing pressure on cod will impact haddock and vice versa. In the project survey data from the two species and the two ecosystems will be analysed and compared focusing on spatial interactions and habitat use.