Energetic limitations and mass mortality of Bering Sea snow crab: Interacting effects of warming and density on collapse and recovery Canadian Journal of Fisheries and Aquatic Sciences

Marine heatwaves can result in mass mortality events, but the mechanisms underlying population collapse and recovery dynamics are often poorly understood. Here, we employed a comparative analysis between collapsing and noncollapsing portions of the Bering Sea snow crab population to evaluate linkages between energetic condition and population abundance during and after a recent collapse. We show that abundance declines during the collapse were associated with dramatic declines in energetic condition, and the negative impact of high population density on energetic reserves was intensified by warming during a marine heatwave. Elevated energetic condition coincided with strong recruitment post-collapse, suggesting rapid initial population recovery in the eastern Bering Sea. However, we show that cold-water habitat (≤0 °C) is critical for supporting high snow crab density in rebuilding towards a pre-collapse state. These results suggest that warming and loss of sea ice will exacerbate the risk of collapse in snow crab through energetic constraints on survival. Furthermore, we highlight the validation of an indirect energetic condition metric that will facilitate continued energetics monitoring and rapid integration into management.