Grey seal

The grey seal (Halichoerus grypus) belongs to the order Carnivora and the family Phocidae. While not a typical agricultural pest for crops, it is recognized as a significant biological hazard in coastal regions where it interacts negatively with aquaculture and industrial fish farming operations.

The primary damage caused by grey seals involves the disruption of fish production facilities. These marine mammals actively target cage systems, tearing nets to access cultivated stock. Such actions lead to the direct loss of fish populations and damage to infrastructure, directly impacting the economic output of coastal agricultural operations.

The biology of the grey seal is characterized by high mobility and a specific seasonal cycle linked to feeding grounds. Their presence near industrial aquaculture sites is often opportunistic, as they learn to associate these farms with stable food sources, creating a persistent pressure on the local aquatic farm management.

The extent of the damage is multifaceted: it includes the immediate consumption of valuable fish, the escape of stock through broken nets, and the operational costs associated with emergency repairs. Furthermore, constant predation pressure causes physiological stress in farmed fish, which negatively affects their growth rates and overall feed conversion efficiency.

Effective management and protection strategies for aquaculture farms include several key approaches:

• Deployment of high-tensile strength anti-predator netting.
• Implementation of acoustic deterrent devices to discourage seal approach.
• Structural fortification of cage frames to prevent predator entry.
• Regular underwater monitoring and maintenance of containment infrastructure.