Gillnet fisheries represent a significant industry engaged in fishing through the use of gillnets or entanglements in the mesh.

Gillnets demonstrate strong selectivity, targeting specific fish species while minimizing the capture of other marine life.

They are widely utilized in oceans and inland waters, particularly suitable for catching fish dispersed in the water's middle layer and those near the bottom, including shrimp and crab.

Common targets include herring, tuna, horse mackerel, mackerel, sea bream, cod, salmon, trout, pomfret, and more, with inland waters seeing catches of mackerel, grass carp, among others. Gillnets come in various structural forms, categorized into five types: single, double, triple, without a lower outline, and frame grid.

Single gillnets, the most commonly used type, consist of a single piece of netting assembled on upper and lower outlines. Double gillnets involve a large-mesh windbreaker and a small-stop net life assembled on upper and lower outlines. Triple gillnets feature two large mesh windbreakers sandwiching a small-stop netting assembled on upper and lower outlines. Gillnets without a lower outline, also known as loose leg gillnets, consist of a single piece of netting assembled on the upper outline. Frame gillnets, or short frame gillnets, are composed of a single piece of netting arranged with longitudinal and transverse ropes to form a frame grid.

Operationally, gillnets are categorized into four modes: drift, set, surround, and drag. Drift gillnets, the most common, are attached to fishing boats and allowed to drift with the current. Fixed gillnets utilize stakes or anchors to secure them in the fishing habitat's water layer. Surrounding gillnets are employed in an encircling manner, often in shallow waters or aquatic grassy areas, using sound and water to frighten fish into the net. Trawling gillnets involve two boats towing a long row of nets to capture fish by entanglement.

The efficiency of gillnets relies on factors such as mesh size, shrinkage coefficient, line thickness, tension, and net color. Mesh size is particularly crucial, as it determines which fish species are targeted. The size of the fish body section that penetrates the mesh is a key consideration in determining the appropriate mesh size. Scholar Baranov's analysis of catch rate curves indicates that gillnets fail to catch fish with a 20% difference from the ideal body length, underscoring the importance of proper mesh sizing.

Determining mesh size can be done based on fish length or weight, assuming linear or cubic relationships, respectively. This data-driven approach helps optimize gillnet design for effective and sustainable fishing practices. Gillnet fisheries play a vital role in global seafood production, requiring careful management to ensure both ecological sustainability and economic viability.

Gillnet fisheries, while effective, also face challenges related to sustainability and environmental impact. Overfishing and bycatch, the unintended capture of non-target species, pose significant threats to marine ecosystems and biodiversity. To address these concerns, sustainable fishing practices, including proper gear management and fishing regulations, are essential. Advancements in technology, such as the use of eco-friendly materials and selective fishing gear, can help minimize the ecological footprint of gillnet fisheries.