The Ross Sea shelf survey
In 2015, an additional source of data from a standardised longline survey of juveniles from the southern Ross Sea shelf area was included in the stock assessment model, to provide information about the relative abundance of juveniles of different ages as they become caught in the fishery.
Ross Sea shelf survey
A Ross Sea shelf survey has been conducted annually since 2012 to monitor juvenile toothfish abundance in three core areas (A,B,C) and to monitor abundance in two additional areas where toothfish predators are most common (N,O). [NIWA]
Survey results have shown that it is possible to track the progression of particular age classes through the shelf portion of population. Knowledge about the relative abundance of each new year class also serves as an early warning system of changes in the population several years before those year classes are fully recruited to the fishery as adolescents on the slope. [NIWA]
Estimated annual relative biomass, and confidence interval, for Antarctic toothfish in the core areas (A, B, and C) in the Ross Sea shelf survey, 2012–2016. The trend of decreasing biomass though 2015, followed by an increase in 2016, is consistent with the growth and movement out of the survey area of one strong year class followed by the appearance of a new strong year class entering the area in 2016. [NIWA]