The SNA 7 stock assessment was extended to the 2020/21 fishing year, incorporating recent CPUE indices, trawl survey abundance indices, and age composition data. The stock is estimated to be above the interim target biomass level. Recent (2019 and 2021) trawl surveys sampled two strong year classes (2017 and 2018) that will recruit into the SNA 7 fishery over the next few years.

Estimates of the fishing efficiency (Q) for 13 species for the R.V. Kaharoa South Island survey trawl gear were made by eliciting expert opinion. Estimates of areal availability taken from generalised additive model (GAM) analyses of the survey data were multiplied to the Q values to estimate overall catchability for seven key species. In five cases (elephant fish, red gurnard, snapper, stargazer, and tarakihi), catchability values were compared with estimates from integrated stock assessments.

A literature review revealed a wide variety of ocean acidification (OA) effects on fish. Tank experiments revealed both positive (growth and survival) and negative effects (metabolic performance and hearing) of OA and elevated temperature on snapper. A snapper population model that adjusted parameters to account for OA and elevated temperature suggested positive and negative outcomes were possible. Given this, further data collection and frequent monitoring to inform management would be prudent.

This study used deep learning to provide an automatic estimation of age for hoki and snapper through a convolutional neural network (CNN). A reference library of otolith images from ~1060 hoki and 520 snapper was generated for use in the CNN. Results from models using these images suggest that deep learning has the potential to support the automation of fish ageing, although further research is required to build an operational tool useful for routine fish ageing.

A period of parallel reporting of fishing effort was carried out in 2019, using the statutory paper forms alongside early adoption of electronic reporting. Twenty vessels, mainly active in the northern snapper (SNA 1) fishery, actively participated in the trial, providing 294 vessel-days of parallel reporting data. Overall, the study indicates no major concerns for the generation of trawl or bottom longline fishery CPUE indices with continuity across the change in reporting regime.

This report provides estimates of changes in the recreational harvest from SNA 8 that could occur given incremental increases in the recreational minimum legal size limit and incremental reductions of the daily bag limit. These estimates are based on an analysis of boat ramp interview data collected over a 5 year period spanning the 2015–16 to 2019–20 fishing years. These analyses suggest that modest changes to recreational limits would have little effect on recreational harvesting from SNA 8.

Recent trends in the SNA 8 fishery are summarised. Standardised CPUE indices are updated. Data were incorporated in a stock assessment model for SNA 8 which integrates commercial catches, recreational catch estimates, tagging biomass estimates, trawl survey indices, and age and length composition data. Spawning biomass estimates increased considerably over the last decade due to an increase in recruitment from the mid 2000s. The 2021 biomass was estimated to exceed the target level (40% SB0).

An overview of electronic monitoring programmes for New Zealand fisheries carried out during the 2016 to 2018 fishing years is provided, summarising the coverage achieved and identifying lessons learnt. The programmes achieved a high level of coverage of the FMA 1 trawl and longline fisheries, introducing innovative monitoring technologies that facilitated significant new data collection. Vessel and video observation estimates of sub-MLS snapper returns to the sea were broadly consistent.

Age composition of snapper caught by bottom trawl in the SNA 7 area was estimated for the 2019–20 fishing year. A total of 999 otoliths were selected from 25 qualifying landings. The 2015, 2011, and 2008 year classes collectively accounted for 52% of fish landed. Although these year classes will likely be important to the fishery for many years, there was also evidence of high inter-annual recruitment variability. The mean weighted coefficient of variation for the SNA 7 age composition was 21%.

In this report, five criteria were used to identify which species future research into recreational release mortality should focus on. The four highest priority species were: snapper, blue cod, kingfish, and kahawai. Relevant national and international published studies that have investigated the relative incidence and possible causes of recreational release mortality for these species are reviewed, and experimental methods are proposed, to further investigate this issue.