loading page

The impact of sea-ice drift and ocean circulation on dispersal of toothfish eggs and juveniles in the Ross Sea and Amundsen Sea
  • +2
  • Erik Behrens,
  • Matt H Pinkerton,
  • Steve Parker,
  • Graham Rickard,
  • Charine Collins
Erik Behrens
NIWA

Corresponding Author:[email protected]

Author Profile
Matt H Pinkerton
National Institute of Water and Atmosphere Research
Author Profile
Steve Parker
National Institute of Water and Atmosphere Research
Author Profile
Graham Rickard
National Institute of Water and Atmospheric Research (NIWA)
Author Profile
Charine Collins
National Institute of Water and Atmosphere Research
Author Profile

Abstract

Knowledge about the early life history of Antarctic toothfish (Dissostichus mawsoni) is still incomplete, particularly on the spatial and temporal extent of spawning and the subsequent transport of eggs and juveniles from the offshore spawning areas to the continental shelf. This study used a high-resolution hydrodynamic model to investigate the impact of ocean circulation and sea-ice drift on the dispersal of eggs and juvenile Antarctic toothfish. The virtual eggs were released on seamounts of the Pacific-Antarctic ridge in the northern Ross Sea and advected using hydrodynamical model data. Particles were seeded annually over a 14-year period (2002 to 2016) and tracked for three years after release. Spawning success was evaluated based on the number of juveniles that reached known coastal recruitment areas, in the eastern Ross and Amundsen Sea, within three years. Observations show that juveniles (50-100 cm size class) are abundant on the shelf and slope of the Ross and Amundsen Seas. Sensitivities to certain juvenile behaviours were explored and showed that spawning success was reduced by around 70% if juveniles drifted with sea-ice during the second winter season as this carried them into the open ocean away from the shelf region. Spawning success increased during the second winter season if juveniles were entrained in the Ross Gyre circulation or if they actively swam towards the shelf. These modelling results suggest that the ecological advantage of sea-ice association in the early life cycle of toothfish diminishes as they grow, promoting a behaviour change during their second winter.