The Gulf of America Hypoxia Watch maps near real-time bottom dissolved oxygen data to monitor hypoxic conditions in the Gulf of America. Data is collected during the NOAA Fisheries annual Summer Groundfish Survey, which evaluates the population and health of commercially important shrimp, fish, and other marine organisms relative to environmental conditions in the Gulf as part of the Southeast Area Monitoring and Assessment Program (SEAMAP), a federal, state, and university cooperative. Oxygen data from the survey are used to generate products that provide updates on hypoxic conditions in the Gulf.
How do I view and access hypoxia watch data?
Hypoxia Watch Interactive Map
Use the Hypoxia Watch interactive map to search, filter, and download data from the hypoxia watch dataset. You can also use our RESTful API services to download larger ammounts of data, or integrate the data into other software applications.
Product Resources
What is Hypoxia?
Hypoxia occurs when oxygen levels in a body of water become too low to support marine life. It is typically associated with high levels of nutrient runoff that stimulate an overgrowth of algae that, when they die, sink to the bottom and decompose and lead to oxygen depletion in bottom waters. Hypoxia can devastate aquatic ecosystems by driving away fish, invertebrates, and mammals, and killing or weakening organisms that can’t relocate quickly.
Where and when does hypoxia occur? What causes it?
The largest hypoxic zone in U.S. coastal waters—and second largest in the world—is located in the northern Gulf of America on the Louisiana/Mississippi continental shelf, impacting an area about the size of the state of New Jersey. While hypoxia can occur naturally, there is strong evidence that nutrient pollution caused by runoff from industry and agriculture within the Mississippi River watershed significantly contribute to its presence in the Gulf.
The westward moving currents in the Gulf of America cause the hypoxic zone to occur more frequently west of the Mississippi River outflow, commonly referred to as the “Dead Zone”, as shown below. While hypoxic waters can develop anywhere under the right conditions (i.e. green areas of the map), monitoring efforts are focused to the west of the Mississippi/Atchafalaya River outflows as they more experience hypoxia more frequently (i.e. red areas of the map). Hypoxic waters do occur to the east of the Mississippi though and are dominated by other freshwater inputs to the Gulf (i.e. Mobile Bay).
More Information About Hypoxia
- The Problem of Hypoxia in the Northern Gulf of America
- The Causes of Hypoxia in the Northern Gulf of America
- Hypoxia Watch Handout
- Gulf of America Hypoxia Monitoring Implementation Plan
- Hypoxia Task Force 2019 Report to Congress
- NOAA's National Ocean Service: Hypoxia in the Gulf of America
- Louisiana Universities Marine Consortium (LUMCON) Hypoxia Research
- Texas Automated Buoy System (TABS) Hourly 3-day Dissolved Oxygen Forecast
Organizations
About the Survey
This predetermined, stratified random survey samples fish and invertebrates using trawls or bongo and neuston nets, and deploys an environmental profiler to measure water temperature, conductivity, dissolved oxygen, fluorescence, and transmittance continuously from the surface to the sea floor. Samples and data are collected from stations located east of the Mississippi River and in the area between the 10 and 200 m isobaths from Brownsville, Texas eastward to the Florida Panhandle.
Due to COVID-19 restrictions, the Summer Groundfish Cruise did not sail in 2020. In 2022, the Oregon II was not in operation.
Current Cruise Details
Last Update: May 26, 2026
Opening the Map Viewer
When the interactive map viewer is first opened with no filters applied, it will display the Hypoxia Stations and Contours layers of the most current year. During the hypoxic season (June-August), the map viewer will open to the latest map updates.
The map viewer has eight dropdown menus, and the contents are described below.
The map has interactive table view (Figure 1) that works well with accessibility tools like screen readers. The table can show or hide tabular versions of the data for each map layer, and also provides filtered and bulk download options. The table includes all the same filtering options and data layers as the interactive map.
Use the Timeline and Time Based Layers section (Figure 2) to show data from a specific date or time period on the map. It includes one layer for hypoxia stations and three hypoxia contour layers:
- Historical Hypoxia Watch map symbology
- Updated alternate symbology using the cmocean colorscheme for “oxy”,
- Accessible symbology which uses patterns for better contrast.
Click the arrows to the left of the timeline to move it forward or backward in the display. Use the three dot menu on the right side of each layer to make the layer graphics more or less transparent (Figure 3).
Use the timeline slider to view data from any year or date range in the dataset's period of record (2001-present). Drag the blue timeline feature to display data for more than one year at a time, or use the arrows (Figure 4) to browse the data year-by-year.
We recommend only displaying one year when using the links and downloads section, which only shows links for one year at a time. See the links and downloads dropdown below for more information.
Ancillary data layers (Figure 5) include data that compliment the core hypoxia watch data. The ancillary layers are:
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Hypoxia Occurence 2001-2023
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2008 Fall Cruise
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Bathymetry Contours
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Mean Sea Surface Temperatures
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30 year Annual Ocean Surface Currents Climatology
See the details section (elipses/three dot menu on the right side of each layer) for more information about each dataset. If you add data to the map (see the Add Data section below), it will show up in the Ancillary Data layer list.
You can temporarilly add GIS data to the map by pulling from your ArcOnline account, pasting a link, or uploading a local file. Once the data has been added to the maps it will appear under the “Ancillary Data Layers” section. To add layers:
- Use the blue "+" button in the bottom right part of the section to browse ESRI resources or link/upload your own data (Figure 6).
- Once your dataset loads in the “Add Data” panel, use the four dot menu button (see Figure 7) to “Add to map”. This will add the layers to your map view (Figure 8).
The legend (Figure 9) shows the graphics that represent each data layer. The legend updates dynamically when layers are toggled on or off.
The links and downloads section (Figure 10) includes links to archived datasets at NCEI and zipped shapefile packages. It dynamically updates to show the links that correspond with the current map settings.*
- "XXXX CTD Stations Zipped Package” and “XXXX CTD Contours Zipped Package”: redirects to a folder that contains shapefiles for the selected year.
- “XXXX CTD Stations Map” and “XXXX CTD Contours Map”: Links to the jpeg maps for stations and the contours created by NCEI.
- “XXXX Stations Metadata” and “XXXX Dissolved Oxygen Contours Metadata”: Link to a folder that contains the metadata for each of the shapefiles created by NCEI.
- “XXXX Archive Link”: Links to web pages for archived datasets that include the entire Conductivity (Salinity), Temperature, and Depth (CTD) casts for that cruise year.
- “XXXX CSV Link”: Downloads a CSV file of the bottom dissolved oxygen values pulled from the CTD casts for that cruise season that was used to create the hypoxia contour layers.
*NOTE: This section will only show shapefiles and archived datasets for one year at a time. If the map is set to show multiple years (e.g.,2013-2020), the links in this section will only archived datasets for the earliest year in the timeline (i.e., 2013).
To view multiple years of data, use the data table view to access the data. The data table view has a column that links to the accession web page of each datapoint for ease of access to the individual archives.
Use the measure tool (Figure 11) to measure distance or area on the map. Start by clicking the map to place your first point and double click to place the final point on the map.
The print tool (Figure 12) allows you to export the map display to a printible file format like a PDF. You can add a custom title, include authorship or copyright info, change the scale and units of meausurement, and tweak the format for different layouts.
The selection tool (Figure 13) is located at the top left corner of the map. You can click the tool icon to use the default rectangular bounding box, or use the dropdown to browse other selection and containment options (see Figure 9).
Make a selection based on your map and double click the last point to complete (Figure 14).
The selection will highlight in blue on the station and contours layers. The bottom right will show the amount of selected features and the top right will show the total amount of features (Figure 15).
The selected data can be viewed in tabular format in the “Data Table” view of the map and selecting “Show Selection” (Figure 16).
From here the selected data (Figure 17) can be exported using the export tool also located in the top right corner of the table viewer under the four dot menu button (Next Section of User Guide).
To export the data table, click on the menu on the top right of the data table view. Then choose your preferred file format.
