Barry, K. L.. University of Michigan/Great Lakes Environmental Research Lab, barry@glerl.noaa.gov
Demers, E. L.. University of Michigan/Great Lakes Environmental Research Lab, demers@glerl.noaa.gov
Brandt, S. B.. NOAA-Great Lakes Environmental Research Lab, brandt@glerl.noaa.gov

 
INFLUENCE OF SMALL-SCALE PHYSICAL FEATURES ON FISH PRODUCTION: ACOUSTIC MEASUREMENTS OF FISH ABUNDANCE NEAR FRONTS IN CHESAPEAKE BAY
 
Estuarine fronts, resulting from plumes and tidal mixing, have been identified as areas of enhanced biological productivity. By altering water movements and vertical stability of the water column, fronts influence prey availability and environmental growing conditions (i.e., temperature, oxygen) for fish which ultimately regulate production. The goal of this study was to assess the influence of fronts on spatial and temporal patterns of fish abundance and distribution in Chesapeake Bay. Sampling took place near the mouth of Chesapeake Bay during April, July and October in 1997. Fish abundance and distribution were measured with a split-beam underwater acoustic system. At the same time, surface environmental conditions were measured continuously with ship-board sensors and vertical profiles of conductivity, temperature and dissolved oxygen were obtained. Fronts occurred during all sampling periods and were characterized by horizontal and vertical physico-chemical gradients and, in many cases, an obvious surface signal. Fish were often spatially distributed along the pycnocline in the frontal zones, and internal waves were also apparent. Although estuarine fronts are episodic physical features, the dynamic and patchy nature of the physical, chemical and biological conditions have important ecological implications for the growth of small and large fish.
 
Day: Thursday, Feb. 4
Time: 09:15 - 09:30am
Location: Hilton of Santa Fe
 
Code: SS04TH0915H