Biogeography of tuna and billfish communities
Aim The aims of this study were: (1) to identify global communities of tuna and billfish species through quantitative statistical analyses of global fisheries data; (2) to describe the spatial distribution, main environmental drivers and species composition of each community detected; and (3) to determine whether the spatial distribution of each community could be linked to the environmental conditions that affect lower trophic levels by comparing the partitions identified in this study with Longhurst’s biogeochemical provinces.
Location The global ocean from 60° S to 65° N.
Methods We implemented a new numerical procedure based on a hierarchical clustering method and a nonparametric probabilistic test to divide the oceanic biosphere into biomes and ecoregions. This procedure was applied to a database that comprised standardized data on commercial longline catches for 15 different species of tuna and billfish over a period of more than 50 years (i.e. 1953–2007). For each ecoregion identified (i.e. characteristic tuna and billfish community), we analysed the relationships between species composition and environmental factors. Finally, we compared the biogeochemical provinces of Longhurst with the ecoregions that we identified.
Results Tuna and billfish species form nine well‐defined communities across the global ocean. Each community occurs in regions with specific environmental conditions and shows a distinctive species composition. High similarity (68.8% homogeneity) between the spatial distribution of the communities of tuna and billfish and the biogeochemical provinces suggests a strong relationship between these species and the physical and chemical characteristics of the global ocean.
Main conclusions Despite their high tolerance for a wide range of environmental conditions, these highly migratory species are partitioned into clear geographical communities in the ocean at a global scale. The similarity between biogeochemical and biotic divisions in the ocean suggests that the global ocean is a mosaic of large biogeographical ecosystems, each characterized by specific environmental conditions that have a strong effect on the composition of the trophic web.
Document Type: Research Article
Affiliations: 1: Institut de Recherche pour le Développement (IRD), UMR EME 212, Centre de Recherches Halieutiques Méditerranéennes et Tropicales, Av. Jean Monnet, BP 171, 34203 Sète Cedex, France 2: Centre National de la Recherche Scientifique (CNRS), Laboratoire d’Océanologie et de Géosciences, UMR LOG CNRS 8187, Station Marine, Université des Sciences et Technologies de Lille – Lille 1, BP 80, 62930 Wimereux, France 3: Institut Français de Recherche pour l’Exploitation de la Mer (IFREMER), UMR EME 212, Centre de Recherches Halieutiques Méditerranéennes et Tropicales, Av. Jean Monnet, BP 171, 34203 Sète Cedex, France
Publication date: 2012-01-01