Modelling spatial distribution of Patagonian toothfish through life-stages and sex and its implications for the fishery on the Kerguelen Plateau
Size and sex speciﬁc habitat preferences are common in animal populations and can have important implications for sound spatial management of harvested species. Patagonian toothﬁsh (Dissostichus eleginoides) is a commercially exploited ﬁsh species characterised by its longevity (\textgreater50 yo) and its extremely broad distribution in depths ranging from 10 m to 2500 m on most of the Plateaux, banks and seamounts of the Southern Ocean. As many bentho-pelagic ﬁsh species, Patagonian toothﬁsh exhibits sexual dimorphism and ontogenetic habitat shift towards deeper waters as they grow. In this study, we modelled the spatial structure of Patagonian toothﬁsh population (median total length and sex composition) in a data-rich area, the Kerguelen Plateau (Southern Indian Ocean), to better understand the ecological drivers of their distributional patterns and inform current and future ﬁshery management strategies. We applied spatially-explicit statistical models to quantify and predict the effects of the complex topography of the Kerguelen Plateau in structuring the spatial distribution of Patagonian toothﬁsh total length and sex ratio, while controlling for gear selectivity and season. Model predictions showed that juvenile toothﬁsh live in shallow regions (shelf and banks) and move downward progressively up to 600 m while they grow. Between 600 m and 1200 m, the downward movement stops and ﬁsh settle at their preferred depths. While in this depth range, ﬁsh are \$75 cm long and most vulnerable to ﬁsheries. As they approach maturity large ﬁsh move downward to deep-sea habitats (from 1200 m to \textgreater2300 m) and head towards the spawning grounds on the western side of the plateau and around Skiff Bank. Importantly, the sex ratio was not evenly distributed across the Plateau; prediction maps revealed a higher proportion of females in the South whereas a strong male-bias sex ratio (70\%) occurred in the North-West. Large-scale prediction maps derived from our models assisted in developing hypotheses regarding ecological drivers of Patagonian toothﬁsh habitat-use and movement across different life stages and sex. Such hypotheses are crucial to inform management strategies of this multijurisdictional ﬁshery (France and Australia) at the spatial and temporal scales over which natural processes and ﬁshery extend.
Année de publication
Progress in Oceanography
Nombre de pages
Date de publication
Péron, Clara, Dirk C. Welsford, Philippe Ziegler, Timothy D. Lamb, Nicolas Gasco, Charlotte Chazeau, Romain Sinègre et Guy Duhamel. « Modelling Spatial Distribution Of Patagonian Toothfish Through Life-Stages And Sex And Its Implications For The Fishery On The Kerguelen Plateau ». Progress In Oceanography 141 (2016), 81-95. doi:10.1016/j.pocean.2015.12.003.