Climate change is causing species to shift their phenology, or the timing of recurring life events such as migration and reproduction, in variable and complex ways. This can potentially result in mismatches or asynchronies in food and habitat resources that negatively impact individual fitness, population dynamics, and ecosystem function. This project seeks to improve our understanding of shifts in the timing of seasonal migration and spawning of adult anadromous alewife, Alosa psuedoherengus in seven natal stream systems within the state of Massachusetts: Acushnet, Agawam, Herring, Jones, Nemasket, Stoney Brook, and Town Brook Rivers. Initial analyses examined if and how the direction and magnitude of annual spawning run initiation, peak and end dates have shifted over recent decades. Preliminary results suggest that changes in alewife migration timing are not consistent across runs within Massachusetts. Trends from an overall analysis of all sites show a shift of earlier timing in run initiation dates and a shift towards later run end dates. Ongoing work seeks to evaluate the extent of estuarine habitat availability around each of the seven run sites; this will be accomplished by measuring the area of continuous wetland habitat downstream from alewife spawning ponds. Additionally, shifts in the timing of alewife migration in relation to environmental conditions such as river and sea surface temperature, river flow and winter conditions will be evaluated. Project results will help managers assess the vulnerability of alewife and other coastal species to the interactive effects of environmental and anthropogenic stressors influencing their populations across the region.
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