VIMS Vessel R/V Bay Eagle
We fish from the R/V Bay Eagle , a 65' aluminum hull, twin diesel-engine vessel capable of housing crew and scientists for multi-day deployments. The vessel is fully equipped with navigational electronics, dry lab, wet lab, galley, mess and sleeping quarters. We have rigged the vessel to be an efficient trawler by constructing and installing a removable modular platform, trawling winch, A-frame, and net reel.
Gear
Our net constructed by Reidar Manufacturing Inc. is a 45-foot 4-seam balloon otter trawl with 6-inch stretch mesh in the wings and body, and 3-inch stretch mesh in the cod end, with no liner. The doors are four-foot steel V doors weighing 185lbs. each, with a 'tickler chain' attached between them.
We use three Netmind sensors – one on each wing and one on the headrope. This allows us to measure the net width and height in real time to assure the net is fishing properly.
* Courtesy of Netmind
Stations
ChesMMAP has five cruises a year, occurring in the months of March, May, July, September and November. Each cruise samples 80 stations ranging from just outside the Chesapeake Bay Bridge Tunnel north to Poole’s Island (near Baltimore, MD).
We divide the bay into 5 regions and stations are selected prior to each cruise. Stations are selected according to a random stratified design, incorporating both latitudinal and depth strata.
At each station the net is trawled along the bottom for 20 minutes, with the current, at a speed of 3.0-3.3 knots. All work is completed during daylight hours and each cruise takes approximately 8 working days to complete.
Data collected
At each sampling location atmospheric data is collected along with hydrographic data at both the surface and the bottom of the water column.
The catch at each station is sorted by species and size class. For each species-size group combination, an aggregate weight is obtained and individual lengths taken. For all species, a subsample of 3-5 individuals is taken for further sampling.
Example of size classes in Weakfish
Data taken on subsampled specimens include length, weight, sex, maturity and eviscerated weight. Stomachs and otoliths (or other appropriate aging structure) are removed and taken back to the lab for further analysis (stomach contents and ageing).
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All data is recorded electronically using Limnoterra Fish Measuring Boards. Data is also recorded on habitat and invertebrate species caught in the net.
Pictured to the left: RaeMarie Johnson, Chief Scientist, operating a Limnoterra Fish Measuring Board in the Wet Lab aboard the R/V Bay Eagle. |
