Download FAR 2024/58 Assessment of the Challenger Plateau orange roughy stock for 2024

This report describes research done on an orange roughy fishery on the Challenger Plateau, west of New Zealand, including a small area outside of New Zealand’s Exclusive Economic Zone known as Westpac Bank. The stock was assessed used a computer population model fitted to various data. Those data were fishery catches, scientific surveys of the spawning grounds using bottom trawls and acoustic methods, and estimated ages of the fish, The newest data available to the research was an estimate of the size of the spawning stock in 2023 from a survey.
Some substantial changes were made to the way the modelling was done. The most important was that estimates of the size of the stock from different areas on the Challenger were added up to give a total stock size. Previously, three areas (Volcano, West, and East) had been treated independently. There were other changes to the way the productivity of the stock was estimated, the relative importance given to each of the data sets, which data sets were included in the model, with some other changes to the statistical settings of the model.
The size of the stock before fishing started (the virgin spawning stock size, B0), was estimated to be about 99 400 t, and the stock in 2024 reduced to about 35% of this level. The future productivity of the stock was a concern. The stock was substantially reduced by fishing in the 1980s and 1990s, and if that caused a reduction in reproduction, then the consequences will now be felt, as a current reduction in the numbers of young fish arriving into the fishery.