Download FAR 2024/20 Investigating monitoring and assessment approaches for oreo species

Two oreo species, black oreo and smooth oreo, are commercially important in New Zealand waters. Oreos are deepwater fish and so are not very productive which means they can be easily over-exploited.

Management is based on setting catch quota for each oreo management area, but some areas have localised fisheries which are assessed separately to avoid over-exploitation.

To assess if catch quotas are sustainable, abundance trends are produced from acoustic surveys and/or catch per unit effort (CPUE) series from the commercial fisheries within a quantitative assessment.

Reductions in fishing effort and quotas have made acoustic surveys too expensive to fund from a levy on catch quotas and CPUE series in several areas have gone from accepted to rejected as a reliable indication of stock abundance trend, so quantitative assessments have been curtailed.

This study considered a range of different assessment methods and their data requirements in anticipation of lower-level monitoring and, for each oreo fishery, presents the monitoring and assessment options.

For two management areas (OEO 3A and OEO 4), acoustic surveys are still considered feasible if redesigned to reduce costs. Quantitative assessments are also considered possible and a method to explicitly consider spatial variation of CPUE within the area is demonstrated in this work as a way to improve the CPUE input data.

For the other main management area (OEO 6), none of the localised areas have sufficient data to continue quantitative assessments and, possibly, insufficient data for any other type of lower-level assessments.