Red drum, also known as redfish or channel bass, are a highly sought-after sport fish found along the Atlantic and Gulf Coasts of the United States. These fish play an important role in marine ecosystems, influencing the populations of various prey species. Understanding their diet provides insight into their ecological role and aids population management.
Primary Food Sources
Red drum are opportunistic carnivores, primarily feeding on animals in marine and estuarine habitats. Their diet consists largely of crustaceans and small finfish. Crustaceans such as blue crabs, white shrimp, and brown shrimp are common components of their meals. A study in Galveston Bay, Texas, found white shrimp made up 60% of their diet by number in the fall, with blue crabs significant across seasons.
Beyond crustaceans, red drum also consume various small fish. These include species like Gulf menhaden, mullet, pinfish, Atlantic croaker, and spot. Gulf menhaden can constitute a substantial portion, reaching 97% of their diet by number in spring, as observed in the Galveston Bay study. Red drum use sight and touch, along with a downturned mouth, to locate food on the bottom, often by “vacuuming” or biting. They can also feed higher in the water column.
Dietary Changes by Life Stage
The diet of red drum transforms as they grow from juveniles to adults. Larval red drum initially feed on microscopic organisms like copepods and mysid shrimp. As they mature into young juveniles, their diet expands to include small crustaceans such as grass shrimp, and tiny fish like killifish.
When red drum reach about 1 to 2 years of age, their diet shifts significantly towards larger prey. Subadult and adult red drum consume bigger crabs, including blue crabs and mud crabs, and a wider variety of fish species. This progression ensures efficient foraging on energetically rewarding prey.
Environmental Influences on Diet
The environment a red drum inhabits greatly influences its foraging choices. Red drum are found in diverse habitats, including shallow estuaries, tidal creeks, and deeper coastal waters. Immature red drum often prefer grass marsh areas of bays and estuaries, where they find ample food sources.
Factors such as water salinity, bottom structure, and the seasonal availability of prey all play a role in shaping their diet. In muddy or grassy bottoms, red drum may feed on burrowing organisms or those seeking refuge in vegetation. Salinity levels also affect feeding efficiency; optimal growth in brackish water suggests dietary needs change with water conditions. The presence of specific prey, like the seasonal abundance of menhaden or shrimp, can lead to distinct dietary patterns in different regions and times of the year.