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Current Conditions of the Northeast U.S. Shelf Ecosystem

September 28, 2023

A current summary of temperature, salinity, chlorophyll and other conditions on the Northeast U.S. Continental Shelf.

Current Conditions

This is a biannual report on ecosystem and fisheries indicators for the Northeast U.S. continental shelf ecosystem. The report includes measurements of temperature and salinity indicators of seasonal warming and cooling patterns. Indicators describing phytoplankton distribution and blooms are derived from satellite remote sensing data. Upper trophic level indicators of fish and macroinvertebrate habitat and distribution dynamics are based on the Northeast Fisheries Science Center bottom trawl surveys.


  • During the first half of 2023, sea surface temperatures in the Northeast U.S. Shelf Ecosystem continued to be well above average. A shift in thermal conditions began around 2010 with a step change of nearly 1°C higher temperatures in most subareas of the ecosystem.
  • The spring thermal transition continues a trend of earlier initiation of spring conditions in the Northeast Shelf, also displaying a step change in transition dates around the year 2010.
  • Spring 2023 phytoplankton blooms in the Gulf of Maine and Scotian Shelf ecoregions were exceptional; the blooms were associated with very high levels of chlorophyll concentration and they persisted past the typical spring bloom time frame into the summer season.
  • The increased chlorophyll concentrations in these ecoregions appear to be caused by a widespread bloom of the dinoflagellate Tripos spp., which is considered unusual for the Gulf of Maine.
  • Fish and macroinvertebrate distributions could not be described in spring 2023 due to an incomplete survey caused by vessel and staffing issues. The absence of these data compromises fishery assessments and our ability to understand climate change effects in the region.
  • An El Niño event that appears to be underway in the Pacific Ocean will be monitored for any effects it may have on the Northeast Shelf Ecosystem.

See the complete report

Previous Report 

Fall 2022202120202019, 2018 , 2017, 2016, 2015, 2014, 2013, 2012, 2011, 2010, 2009, 2008, 2007, and 2006
(reporting on the first six months of the year).

Spring 20232022202120202019, 2018, 2017, 2016, 2015, 2014, 2013, 2012, 2011, 2010, 2009, 2008, 2007, and 2006
(reporting on the last six months of the previous year).

Last updated by Northeast Fisheries Science Center on 09/28/2023