What is longline fishing?

Since 1970, the global abundance of oceanic sharks and rays has declined by a staggering 71%,137 with an 18-fold increase in relative fishing pressure.

Although sustainable shark fisheries are theoretically possible, industrial fisheries targeting elasmobranchs can be characterised by a “boom and bust” trajectory that has decimated crucial species.138

Sharks are now the main target of the EU surface longline fleet (mostly Spanish and Portuguese), with a fishing capacity of more than 200 vessels, each over 24 metres long. This fishing effort is taking place in all of the world’s oceans: on the high seas and even in the exclusive economic zones (EEZs) of some of the poorest countries, under so-called bilateral fisheries agreements with third countries.139

More than 96% of the reported blue shark catches in the North Atlantic are caught by pelagic longlines. These surface longliners carry a line often measuring more than 100 kilometres, targeting just sharks, or sharks and swordfish (though tuna usually accounts for a minor portion of catches). Vessels longer than 24 metres that want to fish for tuna or swordfish in the Atlantic, Pacific or Indian Oceans must register in these RFMOs140 and in ICCAT fisheries, vessels over 20 metres must register.

A hook from a longline, fitted with a wire trace

© Tommy Trenchard / Greenpeace

A drifting longline consists of a main-line or “mother-line” kept near the surface (surface longline) that targets large pelagic fish like swordfish or sharks. Using regularly spaced floats and relatively long snoods (branches) with baited hooks, the gear is suspended about 60-100 metres below the surface. Surface longlines can be huge, from 20 kilometres long to more than 100.

In 2022, a Greenpeace investigation revealed that in a 24 hour period, an estimated 1,280 kilometres of longline were in the North Atlantic (see Figure 6), enough to stretch from Paris to Madrid. We estimate that a longline of this length would have anywhere between 15,500 and 28,000 hooks.

There are currently no regulations limiting longline size or hook usage in the Atlantic because it depends on the target species and the RFMO that manages the area. For example, in Spain, the longline regulation by ICCAT is given by Order AAA/658/2014 of April 22,141 which regulates fishing with surface longline gear for the capture of highly migratory species. The Order regulates the size of the main-line and the number of hooks that can be used, but these measures are only applicable through ICCAT in the Mediterranean. With a maximum main-line length of 30 nautical miles (about 55 kilometres), the number of hooks and their minimum size is determined by the target species. For example, swordfish: 2,500 hooks, albacore tuna: 5,000 hooks, bluefin tuna: 2,000 hooks. However, in the Atlantic, there is no limitation whatsoever on line length or hook usage.