There is nothing new about such invasions. The first recorded case dates to 1245, when Norse voyagers brought a soft-shelled clam to the shores of the North Sea on the sides of their wooden ships. What is new is the rate of introduction and the extent of impact  80 percent of world trade is conducted by ship, and a new marine invader is now recorded in the Mediterranean every four weeks. Zebra mussels have to be power-hosed from the intake pipes of Great Lakes electric companies, and sea squirts form dense colonies that smother the scallops and clams of Georges Bank. According to one estimate, invasive species in the United States cause major environmental damage and losses totaling about $137 billion per year.

There is an easy solution, however: if cargo ships were required to empty and refill their ballast tanks at sea, rather than in harbors and estuaries, marine invasions could be brought to a near standstill. (High-seas ballast water exchange is already mandatory for ships entering the Great Lakes, and will be required next year for vessels mooring in California.) Unfortunately changing ballast water at sea takes time  and time in the shipping industry is money. So far, ship owners the world over have blocked laws seeking to limit shipping’s role in spreading bio-invaders.

In the absence of any concrete action by the shipping industry, I would like to make a modest proposal. To save our oceans and lakes from their apparently inexorable slide back to the Archaean Eon  when all that was moving on the face of the waters was primitive cyanobacteria  it is high time we developed a taste for invasive species.

Diners in Asia, where sesame-oil-drenched jellyfish salad has long been considered a delicious, wholesome dish, are way ahead of us. On the Yangtze River, the Three Gorges Dam, the world’s largest hydroelectric project, has increased the amount of phosphorus and nitrogen in the waters off China, creating an ideal breeding ground for Nomura’s jellyfish, a monstrous 450-pound creature that can tear apart fishing nets. In the summer of 2005, a half-billion were estimated to be floating from the shores of China to the Sea of Japan every day, forming a ring of slime around the entire nation. The citizens of Fukui, a northern Japanese island, coped by marketing souvenir cookies flavored with powdered jellyfish. Returning from a fact-finding mission to China, a professor from Japan’s National Fisheries University offered up 10 different recipes for preparing Nomura’s jellyfish. “Making them a popular food,” he told a Japanese newspaper, “is the best way to solve the problem.”

Precisely. And if we want to forestall our looming carp quagmire, this is the kind of attitude we need to adopt on our shores. Sports fishermen are already doing their part by angling for the pests (as the presence of such titles as International Carper, TotalCarp, and Carpology on magazine racks attests). Restaurateurs from Tupelo to Toronto could pitch in by replacing the bland-fleshed channel catfish on their menus with equally bland-fleshed Asian carp. It seems only fair: it was catfish farmers in the South who imported the fish to filter algae from their ponds in the 1970s and allowed them to escape into the wild during the Mississippi floods of 1993.