female length-at-maturity and cod condition. Natural mortality other than seal predation also 6 depends on cod condition used as an integrative index of changes in environmental conditions. 7The linkage between seals and cod is modeled through a multi-age functional response that was 8 derived from the reconstruction of the seal diet using morphometric relationships and stomach 9 contents of more than 200 seals collected between 1998 and 2001. The model was fitted

There has been a long‐standing debate on what creates stability in food webs. One major finding is that weak interactions can mute the destabilizing potential of strong interactions. Considering that stage structure is common in nature, that existing studies on stability that include population stage structure point in different directions, and the recent theoretical developments in the area of stage structure, there is a need to address the effects of population stage structure in this context. Using simple food web modules, with stage structure in an intermediate consumer, we here begin to theoretically investigate the effects of stage structure on food web stability. We found a general correspondence to previous results such that strong interactions had destabilizing effects and weak interactions that result in decreased energy flux had stabilizing effects. However, we also found a number of novel results connected to stage structure. Interestingly, weak interactions can be destabilizing when they excite other interactions. We also found that cohort cycles and predator–prey cycles did not respond in the same way to increasing interactions strength. We found that the combined effects of two predators feeding on the same prey can strongly destabilize a system. Consistent with previous studies, we also found that stage‐specific feeding can create a refuge effect that leads to a lack of strong destabilization at high interaction strength. Overall, stage structure had both stabilizing and destabilizing aspects. Some effects could be explained by our current understanding of energetic processes; others need additional consideration. Additional aspects such as shunting of energy between stages, control of biomass fluxes, and interactions between lags and energy flux, should be considered.

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SignificanceRecent years have witnessed strenuous ongoing debate about the sustainability of many commercial fisheries. Here we apply commonly accepted principles of fishery science to consider the impact of price flexibility on long-term fishery sustainability in an era of increasing demand due to population increase and rising economic expectations. We apply this model to two commercial oceanic fisheries (cod and pollock) to demonstrate that harvest and price statistics that are commonly available for commercial fisheries can be used to diagnose the degree to which a given fishery has been overharvested. More importantly, the same heuristic can also be used to identify plausible targets for fishery rehabilitation and evaluate the effectiveness of alternative policy options to achieve those goals.