When populations of harvestable fish start to decline, managers look for explanations of the changes throughout the Earth system. In this activity, the impact of global climate change on marine and Great Lakes fish is considered. First, decline in the striped bass population of the North Atlantic, noted in the Downeaster Alexa song by Billy Joel, is examined with spreadsheet analysis and on-line searches of National Marine Fisheries Service databases. In a second investigation, ArcView generates a model of the Lake Erie depths that could be associated with global climate change (shallower water). Students identify fish species that use nearshore shallows for spawning and nursery areas, and speculate on the impact of the lower water. In both activities, the thermal niche of the species is considered as a factor in where fish populations may migrate with new climate regimes.