How a simple wall of nylon became the most efficient trap in the ocean

Gardening · Published 3 October 2026 Swipe more like this →

In short: Gillnets are deceptively simple: vertical walls of mesh designed to snag fish by their gills. While highly effective for targeting specific species like salmon, these nets pose significant risks to marine mammals and sea turtles. Modern technology and strict regulations now attempt to balance this ancient practice with conservation needs.

The mechanics of a gillnet rely on precise mesh sizing. Fish swim into the netting, passing their heads through but finding their bodies too large to follow. As they attempt to reverse, the mesh catches behind their gill covers, effectively trapping them. These nets are categorized into two primary configurations: set gillnets, which are anchored to the seafloor, and drift gillnets, which remain suspended in the water column using weights and buoys.

Historically, gillnetting is an ancient practice, with evidence of its use spanning from Middle Eastern archaeological sites to the traditional methods of North American indigenous peoples. By the 1960s, the introduction of synthetic materials like nylon revolutionized the industry. These fibers were not only more durable and easier to maintain than natural materials like cedar bark or nettles, but their near-invisibility in water significantly increased catch rates.

The high efficiency of gillnets has necessitated complex management. Because the nets do not distinguish between target species—such as cod, tuna, or swordfish—and protected marine life, they can cause significant bycatch. Sea turtles and marine mammals, including humpback whales and dolphins, are vulnerable to entanglement, which can lead to drowning, fatigue, or severe injury. To mitigate these risks, regulators employ various strategies, including the use of acoustic pingers to warn cetaceans, the implementation of time and area closures, and the integration of weak links that allow large whales to break free if they become ensnared.

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