October 28, 2021 — Big fish eat smaller fish, but only if there are smaller fish to eat. A new study led by researchers at William & Mary’s Virginia Institute of Marine Science maps the conditions most suitable for key species of forage fishes in the Chesapeake Bay, offering guidance for any future efforts to protect or restore the habitat required to yield sufficient prey for predatory fishes such as striped bass.
Lead author on the study, which appears in the October issue of Frontiers in Marine Science, is Dr. Mary Fabrizio, a professor and chair of Fisheries Science at VIMS. Co-authors are fellow VIMS researcher Dr. Troy Tuckey, along with Drs. Aaron Bever and Michael MacWilliams of Anchor QEA, LLC. Bever is a VIMS alum.
“Small fishes such as bay anchovy are important components of the diets of predatory fishes in Chesapeake Bay,” says Fabrizio, “but factors that affect local abundances of these forage fish have been largely unexplored.”
To throw light on these factors, the research team set out to quantify and map suitable habitats for four common species of forage fishes in Bay waters, and to assess the relationship between habitat extent and fish abundance. In addition to bay anchovy, the forage species studied were juvenile spot, juvenile spotted hake, and juvenile weakfish.
The team based their study on data generated by counting the number of forage fishes caught in a trawl net during fishery surveys conducted by VIMS and the Maryland Department of Natural Resources between 2000 and 2016. These surveys sample at more than 100 sites throughout the Bay each month. They coupled these catch data with output from computer models simulating the environmental conditions at each sampling site. These conditions include water depth and temperature, salinity, stratification, dissolved-oxygen levels, and current speeds. The researchers also noted whether the bay floor beneath each net tow was sandy or muddy, and the distance to the nearest shoreline.