One of the major issues I discuss in my book published by the University of Michigan Press, The Double-Crested Cormorant: Symbol of Ecological Conflict, is the role the southern catfish industry played in the extraordinary recovery of cormorant populations following the species’ near annihilation due to DDT.
The ban of DDT in the United States in 1972 promised a better future for Phalacrocorax auritus, the double-crested cormorant. Every year thereafter the birds would face lower burdens of the persistent insecticides in their food, eggs, offspring, and environment. What effectively was a booster shot to the cormorant recovery was the virtually simultaneous depletion of predators such as Atlantic salmon and lake trout in the Great Lakes due to overfishing and pollution. As the predators disappeared, populations of both native and non-native forage fish species, preferred food of cormorants, bloomed entirely out of proportion. The birds’ higher reproductive success rates coupled with massive schools of prey there for the taking at their breeding grounds drove cormorant numbers toward previous historic highs. One of the remaining population-controlling factors was the food sources at the cormorant’s southern wintering grounds.
At about the same time commercial fisheries crashed on the Great Lakes, southern row-crop farmers turned to the channel catfish as an alternate or supplemental crop. Catfish farmers never anticipated the fantastic growth in cormorant numbers, so gave little thought to protecting the heavily stocked catfish ponds from wintering cormorants. Thousand, perhaps tens of thousands of double-crested cormorants, fed all winter on the millions of unguarded catfish offered up by the growers. With rich plentiful food at both ends of their migration, cormorant numbers surged further – some local populations doubling in three years. Soaring bird numbers brought increased conflicts with Great Lakes fishermen and southern catfish producers resulting in cruel culling programs legally and illegally killing and wounding thousands of wild, federally protected cormorants.
The issue of the catfish industry affecting cormorant numbers should be taken into account when considering future lethal measures in cormorant management. Many catfish farmers facing huge increases in the cost of corn/soy catfish feed products closed some or all of their production ponds. Some were drained, plowed over, and restored to corn and soybean production. Other ponds were converted to the raising of largemouth bass, cultivated in less densely populated ponds, making them more difficult targets for P. auritus to attack. In either case, fewer catfish were available to hungry wintering cormorants, reducing the number of fatted, healthy birds prepared for the arduous migration north. From 2002 to 2011 every southern catfish-producing state experienced large decreases in acreage dedicated to channel catfish cultivation; overall acreage for U.S. catfish production shrank by 49% in those nine years.
This decrease in U.S. catfish production does not at all relate to the continuing, if not increasing, popularity of catfish fillets as table fare. In the seafood game, domestic farm-raised channel catfish products rank sixth in the United States. The gap in the U.S. between lower catfish production and increased consumption has been filled by foreign imports – particularly Pangasius catfish, farm-raised on the Mekong Delta of Vietnam. If the term Pangasius catfish doesn’t ring a bell it’s because domestic catfish producers lobbied U.S. government agencies to prevent importers from calling this product “catfish.” In American stores it is marketed as Basa fish or bocourti, also two unfamiliar names.
On top of cormorant predation, high production costs, low market prices, and foreign competition, American catfish producers faced another opponent with uncontrollable parameters – nature and the epic floods of 2011. Catfish farms along the Mississippi River Delta faced storm-driven waters which flooded roads, reduced feed supplies, topped their catfish pond levies, released their fish stock into the wild, and in some cases flooded their buildings. The damages and loss of production are yet to be tabulated, but surely what it means is, temporarily at least, catfish farming and production will be reduced even further.
So, all in all, what does this have to do with brutal, bloody sanctioned cormorant kills? Double-crested cormorants have little taste for corn or soybeans. They’re not grain-eating crows or geese; cormorants eat fish and have a predilection for catfish, particularly the penned-up, farm-raised variety. Fewer ponds produce fewer catfish – less winter chow for cormorants. The birds will have to return to foraging the Mississippi River and its tributaries for wild bluegills, perch, and wild channel catfish. And the whole package taken together means fewer healthy cormorants producing fewer healthy offspring.
Since the availability of food is a major limiting force for the expansion or contraction of wildlife populations an alternative then to government contract technicians killing tens of thousands of wild birds might be to let nature simply take its course. The birds wintering in the delta migrate from the northeast and mid-west so anything that places limits on their numbers in the South will send fewer cormorants to their traditional northern breeding grounds and cormorant populations may find newer, reduced numbers, naturally. And maybe the rifles and shotguns can be put away – at least for a while.
My book The Double-Crested Cormorant: Symbol of Ecological Conflict is now available in a trade hardcover version at Amazon.com, Barnes and Noble.com, and the University of Michigan Press, http://www.press.umich.edu/ which also offers an E-book edition. Also, check your local booksellers for availability.
