River Menace to Tasty Pet Food: Market-Based Solutions for Invasive Carp

Run a motorboat up the Mississippi River in summer, and you’re likely to get smacked in the face by a fish the size of a baseball bat.

Silver carp, which exhibit a uniquely frightful jumping behavior when they feel the vibration of a boat’s engine, is one of four species of invasive carp that are causing environmental damage across the South, Southwest and Midwest, including the Mississippi River basin. Prolific breeders with no natural predators, silver, bighead, black, and grass carp have proliferated in those region’s waterways since being intentionally introduced to the US in the 1970s by catfish farmers and others.

The introduction of the carp was intended to help clean invasive and other weed species from aquaculture ponds. But the fish escaped those ponds, and their high adaptability quickly led them to dominate waterways, where they constitute up to 95% of the biomass of some bodies of water.

The fish were also once viewed as a savior of sorts. I grew up north of Houston, Texas, near Lake Conroe, which in the late 1970s was overtaken by Hydrilla verticillata, a fast-growing invasive weed that snared boat propellers, skiers, swimmers and fishing lines. My 10^th grade Science Fair project was focused on getting rid of the plant, and grass carp was my solution. (The project took first place in the biology division at Spring High School!) In 1981-82, 270,000 grass carp were deployed into Lake Conroe, and by the fall of 1983 all the hydrilla had disappeared — as well as most other aquatic vegetation, infuriating anglers.

While grass carp did not demonstrate the jumping behavior of their silver carp cousins, they and their carp kin nevertheless proved to be a growing menace, crowding out other species. Now, however, a potential market-based solution to this longstanding problem has emerged.

Carp are highly nutritious and much prized in many parts of the world. Contrary to popular conception, carp aren’t bottom feeders, and they have some of the highest levels of protein and omega-3 fatty acids found in freshwater fish. But their bony body structure makes them difficult to fillet for human food, so far limiting their commercial prospects.

Enter the pet food industry, which has begun to embrace carp for fanciful treats for cats and dogs. Bones do not pose the same problem in pet food as they do in human food, and ground bone actually contains important nutrients for pets. So several companies have begun selling carp-based pet treats.

Some pet food companies have been wary of embracing carp because, as with many invasive species, eradication is the ultimate goal — and what company would invest in bringing to market a product that might not be available in the future? Elimination of carp is highly unlikely, however, given carp’s ability to rapidly expand their populations. The goal is to keep it in check.

Julia Kurnik, Senior Director of Innovation Startups at WWF’s Markets Institute, is working with pet food companies to build market demand for carp, using economic forces to address an invasive species and its environmental harm. The final results, judged as tasty in numerous feline and canine trials, will depend on year round harvest rates, processing capacity, and market expansion.

While significant progress has been made in learning about carp’s commercial potential, challenges remain. But general public acceptance of carp as pet food would boost economic development across the Midwest, South and Southwest as the fish are harvested and processed. It would also improve the environmental footprint of pet food supply chains and provide a proof of concept for additional tools to fight invasive species. Not to mention protecting boaters from a particularly dangerous form of flying fish.