OPERATION - Searching for Palinurus barbarae!
The benthic fauna of the Walters Shoal underwent some opportunistic catches and a targeted oceanographic cruise, all of which happened 30 years ago or more. Despite these initial surveys, it was not until 2006 that the existence of the lobster Palinurus barbarae (Groeneveld, Griffiths & Van Dalsen, 2006), was revealed to the scientific world. This spectacular 4-kilogram species has been put forward by the Census of Marine Life which has made it a communication element of biodiversity exploration (http: //www.coml.org/discoveries/discoveries/new_species/spiny.htm). It has certainly been described by scientists, but has been discovered by South African fishermen in Durban, who have been exploiting it for several years by trap fisheries.
We have therefore made every effort to find, during the Walters Shoal expedition, individuals of this new species of giant lobster!
Having been informed of our oceanographic expedition on the Walters Shoal, and in particular of the fact that we would be trying to show the presence of this giant lobster, SAPMER *, the historic operator of large-scale fishing in the waters of the French Southern And Antarctic Lands (TAAF) from Reunion Island, proposed to put at our disposal traps (lobster pots), in order to recapture a descendant of the specimen described a decade ago. We have therefore created a line of lobster pots thanks to the know-how of the crew of the Marion Dufresne and, in particular, thanks to the advice and experience of Arthur, a specialist of trap fishing! To attract these necrophagous species (feeding on dead animals), it was chosen to lure them with mackerel.
The trap line was deposited 125 meters deep on the northwest side of the Walters Shoal. After an immersion of 12 hours, the traps were retrieved by Pierre, the mate of the RV Marion Dufresne and his team. Alas! No lobster. However, the results were interesting because several specimens of crabs, not collected by previous methods (dredges, trawls, dives) could be recorded. The crab is of the genus Naxioides, the Pisinae subfamily and the Majoidae superfamily.
The divers surveyed the summit area of the seamount and did not see a single lobster. Beam trawls were deployed in the area between 200 and 950 meters deep on the flanks of the seamount, and no lobsters either, except three specimens, but at the juvenile stage, measuring only a few centimeters, Determination remains difficult. Many larvae of lobsters, called filosomes, have, however, been collected en masse.
The discovery of a commercial species on the Walters Shoal underlines the challenges for management and conservation of biodiversity associated with this group of seamounts located in areas beyond national jurisdiction and we can wonder about the fact that we did not find it again ten years later.
* Established in 1947, SAPMER operates a fleet of four freezer longliners for toothfish fishing, a freezer lobster trawler for lobster fishing and nine deep-freezer tuna seiners (deep-freezing on -40 ° C) for tuna fishing (Albacore and Listao) in the Indian Ocean. SAPMER is committed to sustainable and responsible fishing with Dolphin Safe membership and obtaining Friends of the Sea, IFS / BRS and FAD-Free * certifications. SAPMER has also participated in numerous oceanographic cruises from 1979 to the present day in the territory of the TAAF, in particular in the setting up of exploratory campaigns, biomass assessment, experimentation of fish marking, habitat mapping, Studies on the impact of fishing gear on marine habitat, etc.
Référence : Groeneveld, J.C., C.L. Griffiths, and A.P. Van Dalsen, 2006. A new species of spiny lobster, Panulirus barbarae (Decapoda, Palinuridae) from Walters Shoals on the Madagascar Ridge. Crustaceana 79(7): 821-833.)