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ChesMMAP Stations

ChesMMAP Regions

ChesMMAP has four cruises a year, occurring in the months of March, June, September, and November.  The coverage includes 80 stations ranging from just outside the Chesapeake Bay Bridge Tunnel north to Poole's Island (near Baltimore, MD). 

We divide the Bay in to 4 regions where Regions A and B comprise Maryland, and Regions C and D comprise Virginia.  Stations are selected prior to each cruise according to a random stratified design, incorporating both latitudinal and depth strata. The March cruise covers Maryland waters only with 35 stations, The June and September cruises cover the whole bay with 80 stations each, and the November cruise covers Virginia waters only with 45 stations. 

At each station the net is trawled along the bottom for 20 minutes, with the current, at a target speed of 3.0 knots. 

Each cruise takes approximately 8 working days to complete.
At each sampling location atmospheric data are recorded along with water quality parameters continuously from surface to bottom (these include, but are not limited to):
  • Station identification parameters - date, station number, stratum
  • Tow parameters - beginning and ending tow location, vessel speed and direction, engine RPMs, duration of tow, water depth, tidal stage.
  • Atmospheric conditions - wind speed & direction, air temperature, relative humidity, barometric pressure, and sea state
  • Water Quality - water temperature, water depth, salinity, dissolved oxygen
  • Invertebrate species - crabs, shrimps, hydroids, dead mans fingers, sponges, etc.
  • Habitat - ghost crab pots, tires, wood, rocks, etc.
After the completion of each tow, the catch is sorted by species and modal size groups. A subsample from each size group is selected for detailed processing. Experience shows that a subsample of 3-5 individuals (3 for very common species, 5 for all others) per species-size group per tow is sufficient for this full processing.

 Weakfish By Size Class

The data collected from each of these subsampled specimens includes:

  • Length (to the nearest mm)
  • Total weight (g)
  • Sex & maturity stage (macroscopic) 
  • Eviscerated weight (g)

Stomachs are removed and those containing prey are preserved onboard for subsequent diet analysis at the shore-based VIMS laboratory. Otoliths or other appropriate ageing structures (e.g., vertebrae, scales, spines, etc.) are removed from each subsampled specimen for later age determination.