Harbor seal

Systematic position: The harbor seal (Phoca vitulina) belongs to the order Carnivora and the family Phocidae. It is a widespread marine mammal species found in temperate and arctic coastal waters of the Northern Hemisphere, known for its adaptability to various coastal environments.

Impacted sectors: While harbor seals are not agricultural pests in the traditional sense, they are recognized as significant predators within the aquaculture industry. Fish farms, particularly those rearing salmonids in open-net pens, are primary targets for their opportunistic feeding behavior.

Biology and life cycle: Harbor seals have an annual life cycle centered around pupping and molting seasons. They are highly intelligent, solitary to gregarious marine mammals. Their foraging habits are primarily opportunistic, targeting a wide range of prey species depending on seasonal availability in their local ecosystem.

Damage and harmfulness: The economic impact on aquaculture is substantial. Seals damage containment nets, allowing fish to escape, and directly prey on stocked fish. Beyond direct losses, the persistent presence of seals near farming sites induces significant stress in the fish population, resulting in reduced feed conversion rates and increased disease susceptibility.

Protection measures: Management of seal interference requires a combination of technical and biological solutions. Protective infrastructure is essential:

• High-tensile, predator-resistant netting systems.
• Installation of acoustic deterrent devices to discourage seal presence.
• Implementation of regular site inspections for structural weaknesses.
• Strategic siting of farms to avoid high-activity haul-out areas.