Big-scale sand smelt

Systematic position: The big-scale sand smelt (Atherina boyeri) belongs to the order Atheriniformes and the family Atherinidae. In agricultural aquaculture, this species is frequently classified as a pest due to its ability to proliferate rapidly and dominate pond ecosystems, thereby undermining the productivity of commercially valuable species.

Biology and life cycle: This species is highly adaptable to varying salinity and temperature conditions. It exhibits a high reproductive rate, with spawning occurring on aquatic vegetation throughout the warmer months. Due to its schooling behavior and short generation time, the population can reach overwhelming densities in enclosed water bodies within a single season.

Type of damage and harmfulness: The primary harm is caused by intense competition for natural food resources, specifically zooplankton and macrobenthos. This directly suppresses the growth rates of fry in aquaculture ponds. Furthermore, a high biomass of this fish can degrade water quality, causing oxygen depletion and increasing the stress levels of the primary cultured fish species.

Affected crops and systems: The pest primarily impacts pond-based aquaculture systems, including those rearing carp, silver carp, grass carp, and sturgeons. In agricultural irrigation systems, massive swarms of sand smelt can clog filtration screens and pump intakes, creating operational difficulties for irrigation machinery and reducing the efficiency of field water supply.

Protection measures: Management strategies to mitigate the impact of the big-scale sand smelt include:

• Regular drainage and desiccation of ponds between production cycles to eliminate eggs and larvae.
• The use of fine-mesh filtration screens at water inlets to prevent the ingress of fish into the farm.
• Introduction of predatory species, such as perch or pike-perch, to exert biological pressure on the population.
• Selective harvesting using specialized small-mesh nets to maintain low population density within the ponds.