Populations, Oceans and Influenza

With world population expected to grow by 3 billion over the course of the next 50 years, managing wild ocean fish stocks and decreasing the environmental consequences of aquaculture production will become increasingly important issues.

In "Fly Rod and Reel" magazine, author Ted Williams notes that U.S. fisheries policy is largely to blame for the ruination of U.S. fish stocks: "[T]he Magnuson Fishery Conservation and Management Act of 1976 ... assured the continued depletion of these stocks [of mackerel, herring, billfish, sharks, tunas and groundfish] by subsidizing the U.S. commercial fleet, which doubled in size from 1977 to 1983..."

Williams notes that the "how we fish instead of just how many fish we extract from the sea" is also import, and notes that "All but two percent of the 235,000 known sea animals live in or on the bottom. So it may do less harm to a fish stock to kill four times the quota with longlines than a quarter of the quota with bottom trawls that clearcut or crush habitat, leveling all structure including cobbles, rocks, corals, sponges, sea fans, mussels, seagrass and kelp... Clearcuts via bottom trawl have been estimated ... to exceed the area of forest clearcuts by a factor of 150," with "each square foot of the world's continental shelves getting razed by bottom trawls every two years."

One of the results of over-harvesting and mismanagement of the world's wild oceans fisheries is the growth in aquaculture, especially in-land aquaculture of carp, tilapia, catfish, eel and shrimp in Asia.

From a base of almost zero in 1976, fin fish production has grown by leaps and bounds, with an average compounded rate of 9.2 percent per year since 1970, compared with only 1.4 percent for captured (wild) fisheries and 2.8 percent for terrestrial farmed meat production systems.

Worldwide aquaculture is now believed to surpass beef production (when compared by weight), and about 30% of the world's seafood is now produced through aquaculture.

The rapid increase in fish production in Asia -- especially in China, Vietnam, and Indonesia -- is why so many zoonotic diseases like Avian Flue are leaping out from the region.

In aquaculture production in Asia, human waste, along withe animal waste, is used to feed carp and catfish in ponds. These ponds, in turn, are routinely dosed with massive amounts of antibiotics to knock down diseases such as ick, flukes, and fungus. The result is a perfect breeding ground for virulent pathogens capable of leaping across the species barrier, from pig to fish, and from bird to human.

It is not an accident that avian flu is turning up in ducks and geese in China, Vietnam and Indonesia. These birds are routinely found swimming and feeding in freshwater aquaculture ponds.

The good news is that it does not (yet) appear that avian flu is capable of being spread from human to human. So long as avian flu continues to need a bird vector, transmission to humans can probably be limited and contained without too much effort.

It only a matter of time before a virulent fish-farm pathogen leaps out and crosses the species barrier to humans with devastating consequences, however. When that happens, no one will blame it on human over-population.