Climate Change, Migration Phenology, and Fisheries Management Interact with Unanticipated Consequences

Accumulating evidence indicates that as global temperatures rise, reproductive behaviors, including migrations, are occurring earlier across a range of taxa. Alone, these changes are ecologically important; however, for some fish populations, management practices may unknowingly interact with climate-induced changes in reproductive phenology, leading to unanticipated changes in fishing mortality. The potential for such an interaction exists for the Chesapeake Bay Striped Bass Morone saxatilis fishery, which opens on the same week each year during the spawning season. Earlier migrants spawn before the fishery opens; however, later migrants are vulnerable to fishing before they reach the spawning grounds. Consequently, if there are climate-induced changes in Striped Bass spawning phenology, unexpected levels of fishing mortality may occur for egg-bearing, prespawn females. To evaluate the potential consequences of this temporally fixed fishing season, we analyzed a time series of gill-net catch data using an inference-based modeling approach to identify the environmental cues driving variation in the migratory timing of Striped Bass onto their two primary spawning grounds. We hypothesized that factors driving migratory timing would also influence the proportion of egg-bearing, prespawn females caught in the fishery each year. Results indicated that spring water temperature was the primary factor influencing the timing of movement onto spawning grounds, with higher temperatures resulting in early migrations. Importantly, our results indicated that in cool years, when females moved onto the spawning grounds later, more egg-bearing females were caught in the fishery before they could spawn. This situation provides impetus for establishing management approaches that reduce potential climate-induced variability in fishing mortality in the Chesapeake Bay and fisheries around the globe. Received December 20, 2012; accepted September 5, 2013