Seabird Mitigation and the Prevalence of Campylobacter spp. at Oyster Farms in the Northern Gulf of Mexico

Abstract

Off-bottom oyster farming provides surface area for seabird perching. Regulatory agencies have concerns about bacterial contamination of oysters from seabird excrement and require operational plans aimed at bird mitigation; however, the effectiveness of many bird deterrents have not been validated. An evaluation of the bird populations at an oyster farm and assessment of a simple, inexpensive, non-lethal bird deterrent were conducted alongside an investigation into the prevalence of Campylobacter spp. in farmed oysters and birds interacting with the floating gear. Seabirds, such as pelicans, cormorants, terns, and gulls were abundant year-round but the use of a deterrent reduced bird-cage interactions by 85%. Campylobacter was isolated from 12 of 206 bird fecal samples and from 10 of 66 oyster samples. Isolates shared the highest 16S rDNA sequence identities with C. lari-like species whose pathogenicities are unknown. Strain-level identification is needed to determine their seafood safety risk. Overall, the simple bird deterrent was effective and may be incorporated to meet operational plan requirements, however the risk of oyster contamination with pathogenic Campylobacter species requires further investigation.