The population density of Orconectes limosus in a mesotrophic lake was assessed in the context of fish and macroinvertebrate biomasses, and crayfish consumption by fish. The average O. limosus (≥6 cm total length) abundance and biomass in the littoral zone was 2200 ind ha^-1 and 32.2 kg ha¹, respectively. O. limosus biomass accounted for a large percentage (49%) of the lake's macroinvertebrate biomass. O. limosus was equal to 35% of the non-predatory fish biomass and to 81% of the predatory fish biomass. O. limosus comprised 15 and 48% of the annual consumption of pike and predatory perch, respectively. Altogether, O. limosus was identified as quantitatively important for the lake's littoral food web, and might also subsidize the pelagic food web. This strengthens the need for an integrated view on lake food webs.