Fishing Methods

Hawksbill sea turtle strangled in line and netting.
Photo: Sea Turtle Stranding and Salvage Network

The main types of fishing methods used are:

• Long-line fishing
• Trawl net fishing
• Drift-net or Gill-net fishing
• Shrimp Fisheries

Sea turtles are migratory and travel thousands of kilometres each year to nest. In 2000, 1.4 billion hooks were cast into the world’s oceans through industrial fishing- snagging more than 200,000 loggerhead sea turtles resulting in the deaths of thousands of them. The threat of fisheries is very serious to the long-term survival of the sea turtle population and to address such issues requires an international solution (Source:

There are three main types of fishing technique employed by the Mediterranean fishing industries which cause the incidental capture of sea turtles. They are long-line fishing, trawl-net fishing and drift-net or gill-net fishing.

Long-line fishing Fast Fact:

A recent study in the scientific journal Ecology Letters estimates that worldwide about 200,000 loggerheads and 50,000 leatherbacks are caught every two years by longlines. Scientists have warned that the Pacific leatherback could go extinct within the next 5-30 years unless immediate action is taken to reverse their slide into oblivion. One of those actions is to impose a Pacific wide moratorium on longline fishing.

Long-line fishing:

In long-line fishing each fishing unit consists of a floating 'mother-line', 300m long, from which hang the hooked 'groundlines', each 25m long, at 20m intervals. Units can be strung together in great chains. It is not unusual for 200 units to be strung together to reach a length of 60Km. This method of fishing is usually used to catch Swordfish and Albacore in the Mediterranean.

Long-line fishing

Trawl net fishing is where a boat drags behind it an enclosed net. The net forms a sock shaped enclosure catching any matter that enters it. The mesh of the trawl net tends to be very small as this type of fishing is primarily used for shrimping. The picture below shows the apparatus used for trawl net fishing.

Trawl net fishing

Drift-net or Gill-net fishing Fast Fact

Known as "curtains of death" because they catch and kill everything in their path, large gillnets (also known as driftnets) were banned by the United Nations on the high seas in 1991. Along with sea turtles, gillnets also injure or kill sperm whales, humpback whales, fin whales, Steller sea lions and other threatened and endangered species. In fact, according to observer data obtained from NOAA Fisheries, 64 dolphins, whales, seals and sea lions have been killed by the gillnet fishery since 2002. (Source:

Drift-net or Gill-net fishing involves the use of huge net. The net is essentially an area of mesh; it is not fixed into any assembly.. The mesh of the net is just large enough to allow the heads of the fish to pass through while trapping them at their gills. The net is usually dragged behind a single boat in a loop or may be fastened to two boats on a parallel course. This type of fishing is usually used to catch Tuna, Swordfish and Albacore. Below is a diagram explaining how a drift-net is used.

Drift net/ Gill-net fishing

Shrimp Fisheries
The highest level of all turtle mortality world-wide is associated with the shrimp trawling industry, which it is calculated kills ten times as many turtles as all other forms of fishing put together (National Research Council 1990). As well as causing the turtles to drown by trapping them in nets underwater for hours, there have recently been reports in the Mediterranean that pollution caused by shrimp farms kills turtles.