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.

The red rock lobster supports the most valuable inshore commercial fishery in New Zealand. This fishery has been managed with catch quotas in nine Quota Management Areas (QMAs), which are usually treated as independent populations or stocks.

To estimate those quotas, a stock assessment is done for each QMA approximately every five years. These stock assessments include a review of the previous stock assessments and data inputs, the addition of new data, data processing, and development of a new stock assessment model.

This document describes the collation and review of inputs for the 2023 stock assessment of CRA 6 (the Chatham Islands).

The trawl footprint describes how much seabed area has been contacted by trawling gear in New Zealand’s territorial sea (TS) and exclusive economic zone (EEZ), but it does not provide a measure of the effect of fishing on seabed communities.

This project used the trawl footprint information, in addition to other sources of information on impacts of contact by trawl gear on seabed fauna, to quantify the potential impacts to seabed communities and habitats.

Fishing gear types were first described and categorised, and footprints for each category of gear were produced. Two published impact assessment methods were applied to the TS and EEZ. The methods had different strengths and weaknesses and the outputs of the two methods were found to be complementary to one another.

The first method applied, the MRSP approach, combines information on gear categories, expert opinion on the vulnerability of seabed fauna to trawl gear, and the bottom contact footprint of trawl fishing. This approach does not consider how the fauna recover over time.

The second method, the relative benthic status (RBS) approach, uses information on the proportion of the seabed area swept by trawls and published information for depletion and recovery rates for seabed fauna considered to be particularly vulnerable to trawling. This method predicts a future state for the seabed fauna assuming no change to fishing effort.

This project provides outputs for both methods that can be used in conjunction with distribution data for seabed fauna to assess impacts of trawling and inform spatial planning processes.

Recognising the shortcomings of the MRSP and RBS approaches, two further approaches were explored and developed using data from the Chatham Rise. One approach aimed to enhance the RBS method by making this more relevant to local seabed fauna by using bycatch data from the Chatham Rise instead of relying on information from international sources. The results were encouraging but indicated that further method development is required.

The second approach expanded a previously applied spatio-temporal modelling approach to assess impacts to fauna thought to be useful indicators of potential trawling effects. It was found that this approach, as with the others, was limited by the available data, and further development is required to improve the utility of this approach in the future.