1Pelagic longline fishing vessels leave a line behind, sometimes dozens of kilometres long, capable of carrying up to 3,600 hooks, which remain adrift for hours. These hooks are baited with mackerel, sardine or squid to attract large pelagic fish such as tuna or swordfish… However, sharks and sometimes protected species such as turtles, certain seabirds and marine mammals are also caught, depending on the fishing ground. And this is not the only disadvantage, as longline fishing uses 350,000 tonnes of natural bait each year, which could just as easily be consumed by humans. A terrible waste, all the more so as only 15% of this bait manages to catch target fish, with the rest being thrown back into the sea. The bait is also being purchased at an ever-increasing price, and must be kept frozen on land and at sea, which represents significant costs for shipowners and fishermen.

Longline by-catch.

2To reduce the environmental and economic costs of natural bait in longline fisheries, research programmes were initiated in 2008. The idea was to replace natural bait with artificial and reusable versions. Various fish-shaped lures were tested on Reunion Island for three years. An environmentally friendly artificial bait (APARE) was developed in 2011, tested and patented by IRD and, to this day, avoids catching protected species. In practice, this reusable soft and punctured shell made of biodegradable polymer can be filled with pulp made from fishery waste. Artificial bait could contribute to reducing production costs while recovering fishery by-products. A number of changes are to be made to the initial prototypes developed. Researchers are currently attempting to implement various improvements, in partnership with industrial companies, and are hoping for a 2025 market launch.

Artificial bait.