The NOAA Chesapeake Bay Office’s Fall 2023 Seasonal Summary notes that higher than average salinity across the Bay may have meant more habitat area for species like spot, croaker, menhaden, and red drum, but less for blue catfish.
The Fall Seasonal Summary is the last of the four seasonal summaries that NCBO will release in 2023. Each summary includes analysis of observations from CBIBS buoys, satellites, and other data sources to determine how Bay conditions compared with the average over the past 20 years. Then scientists explore how those differences may have affected species that live in the Chesapeake Bay.
Water Temperature
In general, the Western Shore tributaries of the Chesapeake had slightly warmer-than-average water temperatures this fall. The Eastern Shore’s water temperatures were slightly cooler than average.
It is possible that the warmer temperatures delayed when some species left the Bay to migrate for the winter.
Satellite data show how waters on the Western Shore were a little warmer, and those on the Eastern Shore were a little cooler, over fall 2023.
Dissolved Oxygen
Earlier this year, scientists shared the good news that the Chesapeake’s “dead zone” for summer 2023 was the smallest since tracking started in 1985. The “dead zone” is the volume of water where dissolved oxygen levels are too low to support much life. The positive trend continued into the fall, as the daily hypoxic volume remained low. That meant species like striped bass and blue crabs had more of the Chesapeake Bay to live in. The remnants of Tropical Storm Ophelia passed by the area in mid-September, bringing rainfall and high winds. That mixed more oxygen into the Bay waters, bringing the hypoxic season to a quick end.
Estimates of daily hypoxic volume show that early fall had only a very small volume of hypoxic water.
Salinity
In much of the Bay, salinity was about average in early fall, then increased to above average in October and November. The higher salinity levels tracked by the buoys were due to lower rainfall amounts in Maryland and Virginia. While higher-than-average salinity can help oysters spawn, it can also increase disease in oysters. Blue catfish have difficulty surviving in waters where the salinity is above 14 ppt, so the higher-than-average salinity may have limited the areas of the Bay where they could live.
Salinity at the Gooses Reef CBIBS buoy was about average until late September, then rose above average for the rest of the season.
Fish Movement
NCBO and partners use acoustic telemetry to track fish movements. Acoustic telemetry receivers can tell when a fish that has been fitted with an acoustic telemetry tag swims nearby. Receivers record tag data such as species, sex, age, and more. Scientists and fishery managers can use this data to learn more about habitat use, migration patterns and timing, and more.
We are starting to analyze telemetry data in the context of water-quality parameters to explore how some species might react to changes in water temperature, dissolved oxygen, and salinity. We will add this analysis to future seasonal summaries.
This map shows where acoustic telemetry receivers are managed by NCBO and partners.
See More!
For a deeper dive into fall 2023 data, more graphs, and discussion on how conditions may have affected living resources, see the full Fall 2023 Seasonal Summary.