Orcasav A new fishing technique for catching Toothfish and avoiding predation by killer whales and accidental snaring of birds

The ORCASAV project involved perfecting a new technique for fishing for Toothfish, replacing longlines with a deep-sea pots for catching large-size fish. To achieve this, the project took advantage of the experience gained by the ITIS project which was aimed at designing pots and traps for targeted fishing. ORCASAV'S object was to take the experiment further to confirm whether the techniques developed solved the problem of birds being trapped and killed and of predation by orcas, while ensuring the solution was economically viable for boat owners. The application of ORCASAV was validated and approved by TAAF (French Southern and Atlantic Territories) and the French fisheries directorate (DPMA - Direction des pêches).

Several pot designs were produced for use at depths of up to 2000 metres. These were firstly tested in tanks and then during ORCASAV missions at sea. Twelve types of pots were tested and compared in the course of more than 3000 operations to set 55 fleets of pots. Comparative fishing trials were carried out alongside authorised longline fishing boats. Thirteen tonnes of Toothfish were caught. Flexible pots, which could be more readily stored on board the boats, proved more effective than rigid pots.

The results were conclusive with not one instance being recorded of a bird dying or predation by sperm and killer whales. The versions produced by Le Drézen Company proved amongst the most effective and robust, particularly as regards two of the models - the ORCASAV 3 and ORCASAV 5. New contacts were established with Australian and New Zealand boat owners for projects to catch Toothfish using the pots.

Some problems did however emerge: current boats being unsuitable for this type of pot fishing (stability, space onboard, etc.) and difficulties regarding equipment maintenance, economic benefits (the need to set a larger number of pots) and, especially, crew safety during the setting of pots. This issue is being studied with Océanic Développement and the Institut Maritime de Prévention (Institute for Maritime Safety). Another key factor was the significant number of crabs caught in the pots. Additional work on escape gaps featured on the pots could reduce the crustacean catch. This would be over and above impact studies carried out on the various crab populations.

It is notable that the project also led to special equipment being developed for undersea video filming to observe the positioning of gear at great depth, the behaviour of fish and the impact on the benthos around the pots.

In the course of the project, several papers and articles were also published (Fishing News, Le Marin, Sciences & Vie, Produits de la Mer, etc.).

The ORCASAV project was jointly recognised by Pôle Mer Bretagne and Pôle Qualitropic in La Réunion.