Age and growth of orange roughy (Hoplostethus atlanticus)

The SIOFA Scientific Committee (SC) is tasked to provide management advice for three important species (orange roughy, splendid alfonsino and Patagonian toothfish) to the Meeting of parties of SIOFA. CMM-15 (2020) paragraph 5 requires that the orange roughy (Hoplostethus atlanticus) stocks shall be assessed every three to five years. The first stock assessments of orange roughy were conducted in 2018 (Cordue 2018a, 2018b) and the second assessments were conducted in 2022 (Roa-Ureta 2022). The next stock assessment is scheduled for completion for SC10 in 2025.
There is some uncertainty in the growth curve estimates and maturity given for orange roughy, and particularly if there are differences between sexes and different areas in the SIOFA Area. In addition, age composition data are also required. Analyses of these data will be used to inform the next stock assessment of orange roughy.
This project builds on the work undertaken by Saunders (2021) and Brouwer et al. (2021) by developing age composition data and updating the growth and maturity curves for orange roughy (Hoplostethus atlanticus) on Walters Shoal (Walter’s shoal, WSR and Seamounts) and on the southwest Indian Rise (Meeting, South Ridge, Middle Ridge and North Ridge) in the SIOFA area, using otoliths collected and held by the Cook Islands.
The previous age estimates will be made available to be included in this analysis to complement the data provided to this project and to evaluate differences in growth by sex, between these areas, and over time. Note, it is possible that not enough otoliths will be available from Southwest Indian Rise to produce sex separated growth curves for that area. In addition, age composition analyses may need to use otoliths aggregated over 2-3 years to obtain an adequate number of samples. The outcomes of this work should be collated in a preliminary report and presentation for SC9 in 2024 and a final report for SC10 in 2025.