A multi-stage, delay differential model of snow crab population dynamics in the Scotian Shelf of Atlantic Canada

Abstract

Snow crab (Chionoecetes opilio) are cold-water stenotherms in the northern hemisphere. As they are long-lived and have a complex life history, developing an operational model of population dynamics has been a challenge, especially in the context of an ever increasing and varied human footprint upon nature. Here we review past efforts at understanding the population dynamics of snow crab in an environmentally and spatiotemporally heterogeneous area, the Scotian Shelf of the northwest Atlantic of Canada. We address these difficulties with a moderately complex multi-stage, delay differential model and parameterize it leveraging Bayesian techniques. Operational solutions were stable and reasonable and permitted inference upon the intra-annual dynamics of snow crab. Further, a concept of a Fisheries footprint, akin to instantaneous fishing mortality rate, can be elucidated that directly addresses the conceptual impact of a fishery upon a non-stationary population. The approach is promising. The model suggests additional processes need to be accounted. We hypothesize that seasonal, interannual movement and spatiotemporally structured predation are key processes that require further attention. However, as computational costs are significant, these additional processes will need to be parameterized carefully.