Stop Carping and Start Cooking: Why Forks and Knives Might Be Useful Tools in the Fight Against a Wetland Menace

Here at Restoration and Resilience, we've spent so much time lately on the Gulf oil spill that smaller (but no less important) environmental priorities have been left idling on the blog's backburner. Ahead of the Fourth of July holiday, we decided to bring one of those neglected topics to the fore.

Up in the air: Besides being an ecological hazard, silverfins and other Asian carp have a tendency to jump out of the water when bothered by passing motorboats. Leaping with the force of small bowling balls, the fish have damaged hulls and injured boaters (Source: University of Missouri)

In this piece, we discuss a subset of conservation jobs that are very important for the Mississippi River Delta – those involving the monitoring and control of invasive species. After blogging about nutria eradication in one of our posts on the Central Wetlands Unit, we decided to focus on another pest stirring up trouble in Louisiana, the Asian carp. We estimate that a $10 million program of catching and processing the fish could help control carp populations while also creating more than 150 jobs annually for people in coastal Louisiana.

Bring along your treble hooks and trotlines as we examine this whale of a problem and fish through the details of a culinary solution.

From Pearl River to Pearl River

"Asian carp" is a broad term for several species of cyprinids that have been harvested for thousands of years in the Far East. While the fish travel far and produce many eggs, these freshwater species did not venture unaided from the Pearl River (in southern China) to the Pearl River (in the Deep South). Instead, their transfer to the Mississippi River Basin, and the problems they quickly caused there, are an interesting case study showing the dangers of invasive species introduction.

The silver carp (Hypophthalmichthys molotrix) and the bighead carp (Hypophthalmichthys nobilis) were imported from China in the early 1970s and brought to Arkansas, where fish farmers used them to control algal blooms in aquaculture ponds. As filter feeders, both cyprinids thrive on plankton and other aquatic species. Like all other members of their genus, silver and bighead carps feed almost continuously, as they have evolved without stomachs. As such, upon introduction to a new body of water, the fish vacuum up extraordinary amounts of food relative to their body weight. While this was initially of benefit to fish farmers with dirty ponds in Arkansas, the carps' enormous appetites soon began to affect native plankton-eating species like the Mississippi paddlefish (Polyodon spathula) and the gizzard shad (Dorosoma cepedianum), which were out-competed by the new arrivals.

By the end of the 1970s, the bighead and silver carp had migrated out of their Arkansas ponds and established themselves in nearby waterways. Upon reaching the Mississippi River, the species rapidly fanned out along its corridor. Today, the carp are a menace from the Great Lakes in the north to the Mississippi River Delta in the south.

This population explosion has proven to be disastrous for local species. The dramatic decline in native fish numbers is directly attributable to carp competition, and the effects have rippled through the food chain. The problem is noted not just in Louisiana, but in other parts of the watershed like the upper reaches of the Mississippi River. In fact, the carp have become so numerous that bowfishermen have taken to hunting them by sight in rivers throughout the South and the Midwest.

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Three summers ago, the U.S. Fish and Wildlife Service officially declared the silver carp an invasive species under the Lacey Act. Still, the fish have continued to multiply and spread. Their relentless range expansion prompted Senator Charles "Chuck" Schumer (D-N.Y.) to request an EPA study of Asian carp in the Great Lakes earlier this year. The fish have even triggered legal disputes between states that have been sent to the Supreme Court.

Eliminating Asian carp is probably impossible, but leaving them to further ruin delicate food chains in Louisiana and beyond isn't acceptable either. What's needed is an approach that will keep carp populations in check.

In traditional Southern style, it might involve killing and grilling.

Tastes Like Chicken?

Blackened or breaded, carp might go well with dirty rice or a plate of chips (Source: Flickr (lsgcp))

Carp have featured on dinner tables for thousands of years, primarily in Asia and eastern Europe. In fact, the common carp (Cyprinus carpio), a less palatable European relative of the silver and bighead varieties, was introduced to the United States as a food source in the 1830s. However, with its characteristically "muddy" tasting flesh, some consumers complained that the carp tasted like…well, you know anagrams.

The unpopular bottomfeeder soon disappeared from kitchen menus, but there's little reason why the common carp's tastier cousins shouldn't have more success with the American public. That's part of the reason for a new burst of interest in harvesting and selling carp. Fishermen and wildlife enthusiasts throughout the Mississippi River Basin have begun thinking about the unloved menace as a potential new menu item. In fact, this past January, the Louisiana Department of Wildlife and Fisheries launched "Silverfin Promotions" to encourage carp consumption.

In China, Russia, and other popular markets for silver and bighead carp, the fish are usually sold fresh, so the processing industry is still in its early stages. One thorny issue is the tendency for carp fillets to be threaded with bones, an unappealing prospect for any diner hoping to whip up a quick fish fry at home. Another impediment is popular perception of the fish. Silver and bighead carp are often erroneously grouped along with other bottom feeders like the common carp, leading people to believe that the fish taste bad without sampling them at all.

While we won't guarantee that they "taste like chicken", silverfin and bighead have their fans, some of whom have compared their taste to a mix between crabmeat and scallops. In addition, both fish have been popular features in Asian meals for centuries, so there are plenty of Chinese and Vietnamese recipes for the fish (in case you tire of homegrown suggestions).

The idea of (literally) eating away at the carp problem is catching on in other parts of the South. In fact, some residents of the Bluegrass State have re-christened the fish the "Kentucky Tuna", and proceeded to market smoked, canned, and fried carp as tasty local substitutes for the "chicken of the sea".

Stop Carping, Start Cooking

Properly processed and promoted, bighead and silverfin could become economical household staples. Bighead fillets are rich in omega-3 fatty acids, and the flesh could serve as a cheap source of imitation crab meat. Mercury levels in carp are also relatively low compared with better-known menu items like bass, mackerel, and tuna, as carp consume small creatures that contribute less to bioaccumulation of toxins. Even the waste products from silverfins and bigheads could be useful. A 150-lb fish yields about 30 lbs. of fillet flesh, and the discarded remnants could be processed into fertilizer for farms in the Mississippi watershed.

(Click to enlarge) Growth in Global Production of Bighead and Silver Carp. Between 1950 and 2008, annual tonnage of silver carp produced grew at an average growth rate of 8.7% year-on-year, while annual tonnage of bighead grew at an average rate of 9.04% (Source: Food and Agriculture Organization of the United Nations (FAO))

Production of both silver and bighead carp has grown tremendously in the past several decades, and seems slated to push higher as demand for meat grows in the developing world. According to the Food and Agriculture Organization (FAO), fish farmers across the globe produced more than $7.76 billion worth of bighead and silver carp in 2008, easily placing the two species among the top freshwater fish in global consumption tables. At the same time, increasing health consciousness in the West has created new markets ripe for healthy, cheap, and sustainable sources of fish. Tilapia has already boomed in this market, and there is little reason why silverfin and bighead could not occupy a niche within it as well. Freezing the fillets could popularize their export to inland regions and increase the pool of customers for this inexpensive and nutritious fish.

Despite the ongoing oil spill and fish factory closures in other parts of the country, Louisiana retains the infrastructure needed for a strong fishing sector. The processing and harvesting of silver and bighead carp could potentially create hundreds of jobs for cannery workers and fishermen in the coastal zone. In addition, the expansion of this sector could create spillover employment in marketing and promotion as a new product is advertised to American consumers.

If we use the respective Year 2006 RIMS II multipliers for fishing (23.0268 jobs per $1 million in spending) and food processing (13.6990 jobs per $1 million in spending) in Louisiana, and adjust their impacts down by 6% to adjust for changes in wage levels and input costs since then, we can preliminarily estimate that a $3 million annual bounty program for catching carp and a $7 million program to process the fish could generate about 65 jobs each year in the local fishing sector (64.94 job-years ≈ 23.0268 job-years per $1 million in spending * (1-0.06) * $3 million in spending on bounty program) and more than 90 jobs each year in canning, transportation, and related industries (90.14 job-years ≈ 13.6990 job-years per $1 million in spending * (1-0.06) * $7 million in spending on food processing). This back-of-the-envelope calculation does not even consider the potential job creation from a more expansive program supported by private investment and philanthropic funding. We might touch on those topics in later posts about Asian carp.

For now, our main point is that from both an economic and ecological perspective, increasing consumption of bighead and silver carp would be beneficial to the Mississippi River Delta. So, as you fire up your grills this weekend and on Fourth of July holidays to come, consider cooking up silverfin fillets along with your traditional summer favorites.