Fish stock assessment of the northern New Caledonian lagoons: 1 - Structure and stocks of coral reef fish communities

Lagoon fish in New Caledonia are mainly caught by artisanal fisheries and s ubsistence fishing. Reef fish are the major component of this catch. The pr esent study aimed at estimating these reef fish standing stocks and at find ing the main factors influencing the distribution of these fish. Sampling o f 904 stations was stratified according to three zones (north, east and wes t) and three reef types (barrier, intermediate and fringing). Fish communit ies exhibited strong heterogeneity in their distribution, showing higher bi omass (maximum of 447 g.m(-2)) and total standing stock (43 000 tonnes) in the north zone than in the east and west zones. Similarly, observed pattern s were dependent on reef types: higher biomass and total standing stock bei ng observed on barrier reefs than on intermediate or fringing reefs. The to tal standing stocks, which were about 65 000 t, were mainly composed of her bivorous fish families such as the Acanthuridae and Scaridae. The differenc es in the patterns of distribution of species, individuals and standing sto cks between reef types may be explained by variations in terrestrial influe nces and reef morphology, whereas differences among zones were most likely due to accessibility of fishing areas and fishing pressure. The latter is a lmost non-existent in the north zone, which can thus be considered to be al most unexploited commercially. This most likely explains the high proportio n, 77 %, of long-lived species in the biomass of this zone. The results mig ht have implications in management of reefs elsewhere in the South Pacific, for which similar data are only scarcely available. (C) 2000 Ifremer/Cnrs/ Inra/Ird/Cemagref/Editions scientifiques et medicales Elsevier SAS.