Great cormorant

The great cormorant (Phalacrocorax carbo) is a member of the Suliformes order and the Phalacrocoracidae family. In the context of commercial aquaculture, this bird is classified as a significant pest that poses a severe threat to the profitability of inland fisheries and fish farms.

The primary crops affected are commercially raised fish, including carp, trout, and perch. Cormorants are highly efficient predators that exploit both natural and artificial water bodies, causing massive losses in stock volume and quality during peak feeding periods.

The biology of the species revolves around intensive foraging. A single cormorant consumes a significant percentage of its body weight in fish daily, and when hunting in large groups (colonies), they can clear entire nursery ponds. Their breeding behavior often involves nesting in colonies that severely damage local vegetation due to the chemical properties of their guano.

Damage assessment reveals that their impact extends beyond direct predation. Cormorants cause physical injuries to fish, making them susceptible to fungal and bacterial infections. Furthermore, high concentrations of bird excrement in small fish ponds contribute to eutrophication and degradation of water quality.

Integrated management strategies for controlling cormorants include:

• Installation of protective overhead netting and tensioned wires.
• Deployment of bio-acoustic deterrents and scarecrows to prevent landing.
• Habitat modification near ponds to reduce roosting attractiveness.
• Active population management and site-specific exclusion measures under environmental regulations.