What Fish Eat Says a Lot About Them—and the Ocean

Research into redfish diets in Florida may illuminate the health of prey species

What Fish Eat Says a Lot About Them
Redfish diets

Edward Camp prepares to release a redfish caught on a lure that imitated a crab near Crystal River, Florida, in 2016.

© Edward Camp

It takes guts for Edward Camp to do his research.

That’s because Camp is analyzing information about the stomach contents of redfish, also known as red drum, to figure out their favorite prey. He is particularly focused on their appetite for forage species—small, schooling fish that feed many marine animals, from whales to birds.

Camp, 33, is one of the first recipients of a $10,000 fellowship sponsored by the Florida Forage Fish Coalition, which is led by the International Game Fish Association and includes The Pew Charitable Trusts, the Florida Wildlife Federation, and the Snook and Gamefish Foundation. The coalition has joined with leading academic institutions and state government researchers to increase the knowledge of scientists and fisheries managers about forage fish, which in turn could lead to policies that better support ecosystem balance and sustainable fisheries.

For Camp, that quest starts in a predator’s stomach.

“The first years of life are the most critical for redfish, when they are most sensitive to changes in habitat and availability of prey,” says Camp, a University of Florida postdoctoral student and newly hired fisheries and aquatic sciences professor. “We don’t know a lot about what these young fish eat and what the most important diet items are.”

Redfish fight tenaciously when hooked and thus are a popular target for anglers in Florida. The species’ population decreased in the late 1980s but has rebounded because regulators limited the size and number of fish that could be caught and barred the catch of breeding-size fish in federal waters.

Redfish diets

Camp presents research on snook—which, like redfish, prey on forage fish. Managers consider prey availability, habitat, and other factors in their plans.

© Courtesy of Edward Camp

Once Camp learns which forage species the redfish prefers, he’ll examine their population records to track how abundant they are. His work should show fishery managers which forage populations are plentiful enough. Camp also might gather similar information about gag grouper.

For this work, Camp isn’t cutting open any redfish but is examining records from the Fish and Wildlife Research Institute (FWRI), which is the research arm of the Florida Fish and Wildlife Conservation Commission (FWC). The institute has data about the stomach contents of hundreds of redfish collected over more than a decade.

Stomach content analysis is a common methodology in fisheries science but has not been extensively used on some species, including redfish. Sometimes fish are dissected, but scientists can also put water into their stomachs and massage the fish until they regurgitate, leaving the fish alive. Scientists often zero in on what a fish has eaten through jaw bones, teeth, ear bones, and other body parts in its stomach. Crabs, Camp says, are easy to recognize because fish sometimes swallow them whole.

Redfish diets

Camp collects specimens on Florida’s Chassahowitzka River in 2009 by electrofishing—in which fish are stunned with electricity but not killed.

© Courtesy of Edward Camp

The toughest part of Camp’s research will be determining which forage species redfish prefer most. Sometimes they might eat whatever’s available instead of venturing off in search of their ideal prey.

“If I ate a hamburger, was it because I wanted it or because it was the only thing available?” Camp explains. “If I had a refrigerator full of salads and I chose the hamburger, then we have a better idea.”

The FWC made forage fish a priority in 2015. The commission adopted a resolution pledging to support scientific research and management that would “ensure sufficient abundance and diversity of forage fish populations” to keep marine ecosystems healthy. Commissioners also promised to take action if forage fish populations declined.

After adopting the resolution, experts formed the Florida Forage Fish Research Program—a public-private partnership of the Florida Forage Fish Coalition, academic institutions, and the FWRI. The research program’s goal is to join forage fish experts in the quest for more information about forage species so they can be properly managed.

Camp is one of two students to receive the coalition’s fellowship. He will work with University of Florida professors Robert Ahrens and Kai Lorenzen. The other fellowship recipient is Meaghan Faletti, a University of South Florida marine science graduate student who is studying the forage species pinfish to determine where they spawn and travel.

“My goal,” Camp says, “is to be able to provide information that helps people make good decisions about natural resources. And one of the most important resources we have are fish.”

Holly Binns directs The Pew Charitable Trusts’ efforts to protect ocean life in the Gulf of Mexico, the U.S. South Atlantic Ocean, and the U.S. Caribbean Sea.