Nautilus pompilius fishing and population decline in the Philippines: A comparison with an unexploited Australian Nautilus population

Baseline capture and mark-and-release studies of Nautilus pompilius conducted at Osprey Reef, Coral Sea, Australia reveal that this unexploited population is stable from a catch per unit effort (CPUE) basis over 12 years. In contrast, data from a detailed interview questionnaire of N. pompilius fishers and traders in Palawan, Philippines highlight a fishery that is unsustainable. The results from the Philippines show up to 80% declines in reported CPUE from 1980 to the present, fewer than three Nautilus generations, which can be attributed to fishing pressure. This is evidence for N. pompilius (and by ecological association, other Nautilus species) to be assessed as ‘endangered’ in the IUCN (International Union for Conservation of Nature) Red List. Questionnaire responses suggested there is no cultural or historical relevance of Nautilus fishing to local communities and the fishery only provides approximately 10–20 years of economic return before becoming non-viable. Identification of new Nautilus fishing sites and training of locals by buyers from distant depleted fishing areas illustrate how the value and demand for Nautilus shells generates fishing pressure.