Bird predation has been an increasingly serious problem for catfish producers since the mid-1980s. Most birds that cause problems are migratory and are therefore protected under the federal Migratory Bird Treaty Act (MBTA). The birds' migratory nature complicates the problem, because predation varies greatly depending on migration patterns, time of the year, migratory concentrations, and the location of catfish ponds. Proximity to nesting or rookery sites can also compound the problem.
Besides eating the fish, these birds can damage property. They are known to transmit fish diseases. Predatory birds consume the individual fish that are easiest to catch. Fish that are easily caught are often those that are diseased. So, the birds pick up diseases and transmit them to other ponds through their excrement and though simple body contact.
Catfish in Alabama are preyed upon by cormorants, egets, and herons throughout the year and by kingfishers and anhingas (water turkeys) during the warmer months. Ospreys and pelicans can sometimes cause problems, too. The occasional visit by solitary kingfishers and ospreys causes little economic damage. Frequent visits by flocks of anhingas, herons, egrets, peicans, and cormorants can be devastating, however. The problem is generally most pronounced in fingerling ponds.
The MBTA is often confused with the endangered species laws. Under the MBTA, migratory birds may not be killed or trapped without permits. But the species mentioned above can be harassed or frightened away from ponds, and habitat alteration and physical barriers are possible methods of control.
Physical barriers can include hanging netting or wires over ponds and erecting fences around the edge of the ponds. These measures are expensive and may cause physical problems to the producer during harvest.
The most common control measures are harassment techniques to frightens birds away from ponds. Birds can be frightened away by:
These measures have had mixed success. Most methods appear to be effective at first, but they become ineffective as the birds get used to them. For this reason, it is best to use a combination of techniques and to frequently move the devices randomly around the ponds.
Producers may contact the U.S. Fish and Wildlife Service and the USDA's Animal and Plant Health Inspection Services (APHIS) for assistance. These agencies will recommend control measures. Permits can be issued to kill birds, if producers keep good records of control measures and estimated losses of fish. These permits are only issued after other methods have proved (by working through agencies and keeping good records) ineffective as certified by he APHIS Animal Damage Control Office. Comply with the law, try creative harassment techniques, report losses to states and federal agencies, and keep good records.