Average spring chlorophyll concentrations in surface waters, as represented by data for April, are illustrated for the four major shelf regions. The most striking feature of these data is the high degree of inter-annual variability in the time series; any perceived trends should be viewed with caution. The trend analysis suggest that chlorophyll concentration may be declining in the Gulf of Maine and may be increasing on Georges Bank, but these trends are not well developed and will have to be monitored. The data for Southern New England and the Mid-Atlantic Bight suggest that the spring bloom has maintained levels without significant trend. Individual yearly data suggest important bloom events may have occurred in the Gulf of Maine and Mid-Atlantic Bight in 2003 and in Southern New England and on Georges Bank in 2004.