Effectiveness of non-lethal laser and acoustic bird deterrents at aquaculture farms in the Midwest, USA

Abstract

Piscivorous birds (e.g. Great Blue Herons, Ardea herodias) often eat fish at aquaculture farms, and this predation may lead to financial burdens that threaten farm operations. To reduce such loss, farmers often implement non-lethal bird deterrents such as gas cannons, reflective tape, and effigies, but birds quickly habituate to these methods, making them ineffective. To help reduce predation at midwestern fish farms, I examined the effectiveness of emerging laser and acoustic non-lethal deterrent technology through observational and camera trap surveys. I administered laser, acoustic, and integrated pest management (IPM; acoustic and laser) treatments that each lasted for 28 days at sites in Kansas and Missouri, USA. Approximately 3 million camera trap images were collected and analyzed using a neural nest artificial intelligence model trained to identify Great Blue Herons. Kernel density estimators were used to examine heron activity over a 24-hour period, and diel activity overlap was calculated between control and study sites to compare activity. Mean heron detections over treatment periods were compared between control and study site cameras with a Kruskal-Wallace test and post-hoc Dunn’s test, and mean heron detections per camera were compared between treatments with Wilcoxon rank sum tests. Linear regression models were fit for each treatment period to examine detection trends over time. Diel activity results indicated that the laser deterrent altered when herons are active. Herons displayed stress behavior such as gular fluttering, delta-wing poses, and prolonged loafing during laser treatment observations. My results indicated that automated lasers may be a viable option to deter birds from fish farms, whereas acoustic sonic net deterrents and IPM approaches may provide limited benefits. The results of my study may enhance economic viability at fish farms by helping producers make informed decisions on what deterrents they should implement at their farms to reduce bird related losses.