Alternative usage of common feeding grounds by large predators: the case of two hakes (Merluccius hubbsi and M-australis) in the southwest Atlantic

摘要

Monthly variations in spatial and depth distributions, sex ratios, and maturity status in two species of hakes, Merluccius hubbsi and M. australis, were analysed in an area where their ranges overlap spatially on the shelf and slope around the Falkland Islands, and in international waters at 45-47degrees S (High Seas), using data collected by scientific observers on commercial fishing vessels. A variety of exploratory analyses were carried out on the raw data before patterns were quantified using generalised additive models. Both species use the areas studied as their feeding grounds. M. australis occur mainly on the Falkland shelf south of 51degrees S, whereas M. hubbsi is widely distributed throughout both the Falkland and High Seas shelf areas. Preliminary schemes of the seasonal migrations of both bakes in Falkland waters and on the High Seas are suggested and discussed. M. hubbsi and M. australis are found to be strongly segregated, both spatially and temporally, on their common feeding grounds, thus avoiding potential inter-specific competition for food resources.