Background <p>Knowledge about the spatial dynamics of fish populations, including social dynamics during the spawning season, is important for ensuring that fisheries management is rooted in ecology. Yet such detailed information about individual fish movement is hard to obtain and therefore typically lacking.</p> Methods <p>We applied network analyses to acoustic telemetry data to study movements and spatial associations of sexually mature Atlantic cod (<i>Gadus morhua</i>) in amid-Norway fjord complex. Cod were caught at five known spawning grounds, acoustically tagged, and released annually at these grounds during 2017–2019. Network analyses using community detection algorithms were then performed on bipartite network graphs for each spawning period (February–April) and feeding period (June–December) to identify spatial groupings or communities of the cod selected for analyses (n_total = 352). Additionally, edge use, i.e. movement between receivers, was analysed for individual cod in the spawning and feeding periods.</p> Results <p>Spawning communities were typically dominated by cod captured and released locally, but commonly also contained fish from other grounds. A tendency for temporal and spatial stability in spawning communities was evident, with 67% of cod monitored over several spawning periods (<i>n</i> = 119) assigned to communities containing at least one common station across years. However, seven cod clearly utilized different spawning sites in different years. Cod detected during both the feeding and spawning period (<i>n</i> = 88) tended to have similar edge use during both periods, with said edge use increasing with fish size. However, eight cod showed either limited movement during spawning and much more extensive movements outside the spawning period or vice versa.</p> Conclusions <p>The network analyses revealed temporal and spatial stability in communities of mature cod during the spawning period. Notwithstanding this, some cod switched their spawning site locality within our regional study area between years. Individual cod tended to have similar edge use during the spawning and feeding periods, although there were examples of cod moving a lot during the spawning period and little outside this period and vice versa. Management should consider such networks of spawning grounds to preserve the intraspecific diversity of movements and the mating system of cod.</p>