These data are part of a ocean observation study by Stabeno, Napp, and Whitledge sponsored, in part, but the North Pacific Research Board (Project 410; http://doc.nprb.org). The grant was titled "Long-term observations on the Bering Sea shelf (2004-2005): biophysical moorings at sites 2 and 4 as sentinels for ecosystem change." Moorings were maintained on the southeastern Bering Sea shelf at M2 (56.9B0N, 164.1B0W), and at M4 (57.9B0N, 168.9B0W). Shipboard measurements of temperature, salinity, nutrients, chlorophyll, fluorescence and zooplankton were collected around the moorings on two cruises (3MF04 - April 2004 and 8MF04 - September 2004) to ground truth in situ sensors on the moorings. This long-term monitoring supported major findings: (1) The timing of the spring phytoplankton bloom is determined by the presence of ice, with an early bloom occurring if ice is present after mid-March and later bloom occurring if there is no sea-ice after mid-March; (2) During the last decade, the southeastern Bering Sea shelf has undergone a marked warming (~3B0C) that is closely associated with a marked decrease of sea ice over the southeastern shelf; (3) Nutrients supply and summer salinity over the shelf has not significantly changed during the last three decades; (4) There is an indication that cold water zooplankton species (e.g Calanus marshallae) are occurring in reduced abundance in association with the warming. While the warming over the southeastern shelf is primarily related to the reduction of ice extent, a combination of other mechanisms are important: the presence over the eastern shelf of a relatively mild air mass during winter since 2000; a shorter ice season caused by a later fall transition and/or earlier spring transition; increased flow through Unimak Pass during winter introducing warm Gulf of Alaska water onto the shelf; and a thermal feedback mechanism whereby warmer, summer ocean temperatures delay the southward advection of sea ice during winter.