Recent outbreaks of campylobacteriosis, a gastrointestinal illness caused by bacteria in the genus Campylobacter, linked to the consumption of raw oysters have raised questions on how oysters become contaminated with Campylobacter. The leading hypothesis implicates seabird interactions with floating oyster aquaculture gear. Due to seafood safety concerns, operational plans are required for oyster farms to deter birds or mitigate their effects. Unfortunately, research related to this issue is limited. This project focuses on three objectives: 1) to survey the species of seabirds interacting at oyster farm sites, 2) to test the efficiency of a simple, inexpensive, nonlethal bird deterrent, and 3) to screen oysters and seabirds found at oyster farm sites for Campylobacter.
Six experimental floating cages were deployed at an experimental oyster plot in the Mississippi Sound, three equipped with a zip tie bird deterrent and the other three serving as non-deterrent controls. Cameras monitored bird interactions at half hour increments. Campylobacter presence in seabird fecal matter was determined using a selective and differential culture medium. An enrichment procedure was used to detect Campylobacter in oysters.
A total of 15 bird species were observed, with Brown Pelicans and Double-crested Cormorants being the most abundant. Bird deterrents reduced bird interactions by approximately 85%. Campylobacter positivity rates for seabird feces and oyster homogenates were 5.9% and 13.4%, respectively. These results do not rule out the potential for birds to transfer Campylobacter to oysters in floating aquaculture gear; however, more information is needed to determine if the Campylobacter species detected present a significant human health risk.