Modelling the early life of Antarctic toothfish

Modelling the early life of Antarctic toothfish

Top: Modelled representation of where Antarctic toothfish spawn.
Bottom: The predicted distribution of eggs and larvae after two years, as they drift with ocean currents away from the spawning grounds.

Antarctic toothfish are found exclusively in waters between 600 S and the Antarctic continent. Very little is known about the life history of this important fisheries species, especially about where they spawn and spend their early years.

NIWA ocean physicists, using models of Ross Sea circulation patterns, are now able to mimic the drift of toothfish eggs and larvae over a 6–24 month period. Current theory is that toothfish spawn to the north of the Antarctic continental slope during winter and spring. The models show that, depending on where spawning occurs, eggs and larvae are then carried either to the west, settling around the Balleny Islands and adjacent continental shelf, or eastwards, settling out to the east of the Ross Sea. The model’s prediction of the location of larvae after 18–24 months fits reasonably well with the distribution of the smallest toothfish in the fishery.

The toothfish fishery is managed under the international treaty, CCAMLR (the Convention for the Conservation of Antarctic Marine Living Resources). NIWA has also developed stock assessment and sustainable harvest models used to manage the fishery. Fishing industry partners have recently applied for environmental certification of the fishery, helping ensure that the stock will continue to be sustainable.

The research was funded by the Foundation for Research, Science & Technology and Ministry of Fisheries.

Research subject: Oceans