Harbor seal

The harbor seal (Phoca vitulina), belonging to the order Carnivora and the family Phocidae, is a species that creates significant operational challenges for the aquaculture sector. While it is a natural predator, its interactions with human-managed fish stocks classify it as a nuisance or biological pest in coastal farming.

The biological cycle of the harbor seal involves breeding and molting seasons that require high caloric intake. When fish farms are located within their foraging range, the seals display opportunistic behavior, targeting the high density of prey concentrated in aquaculture pens.

The damage to agricultural operations is primarily infrastructure-related. Seals engage in biting and tearing of netting materials to gain access to the fish. This physical interaction results in the loss of stock, equipment damage, and significant downtime for repairs required to keep the facility operational.

The economic harm is twofold: direct loss of biomass and indirect costs associated with animal stress. Stress-induced mortality and reduced growth rates in fish, caused by the constant presence of predators around the pens, significantly impact the overall yield of the aquaculture business.

Protection measures are focused on deterrence and exclusion rather than eradication. Industry standards include the installation of predator-resistant nets, tensioning systems for netting to prevent tearing, and the deployment of acoustic harassment devices (AHDs) to deter seals from approaching the site without causing permanent injury.