In past advisories, spring bloom start and peak dates for the Gulf of Maine and George Bank areas were computed using a computer algorithm that analyzed daily chlorophyll data at fine spatial resolution. Problems with ocean color sensors this year have precluded the use of this approach in 2010. Hence, bloom start and peak dates were estimated by partitioning the production cycle based on examining 8-day chlorophyll data records. This approach yields comparable data to previous assessments and, in some cases, provides more accurate results. Historically, the Georges Bank bloom has begun a week earlier than that in the Gulf of Maine. However, in 2010, the Gulf of Maine bloom started earlier (March 14) than that on Georges Bank (March 22). The bloom peak dates in 2010 followed the same pattern, earlier in the Gulf of Maine (April 6) than on Georges Bank (April 14).