This report updates and summarises the commercial catches, standardised catch per unit effort (CPUE), and observer and research data for hoki (Macruronus novaezelandiae) caught commercially during the 2021–22 fishing year.

These data include time series of length-at-age and catch-at-age from observer and land-based sampling of commercial catch. Length and age data from spawning and non-spawning fisheries are compared with those from previous years.

The overall catch in the 2021–22 fishing year was lower than the catch in 2020–21. Catches in 2021–22 decreased in most areas (west coast South Island, Cook Strait, Chatham Rise, Sub-Antarctic, and east coast North Island) and increased in the east coast South Island and Puysegur fisheries. The CPUE indices varied by area but were all at or above the long-term average.

Catch-at-age data are important for the assessment of fish stocks because they provide information on the year class strength of age classes caught and are used in analyses of trawl surveys and commercial fisheries. Most of the catch in 2021–22 was of fish 45–90 cm length from the 2006–2019 year classes.

The 2014 and 2015 year classes were important in all areas except for the Chatham Rise, and the 2016 and 2017 year classes were low in all the main fisheries. The 2018 and 2019 year classes appeared strong in the WC.north, SA.snares, SA.auck, CR.shallow, and CR.deep sub-fisheries.

Biomass indices from research surveys and results from other research on hoki in the most recent year are also briefly described. Data in this report were incorporated in the model for the hoki stock assessment in 2023.

The Marine Ecology Research Group used detailed field surveys to assess the recovery of the inshore coastal ecosystem affected by the cataclysmic 2016 Kaikōura earthquake.

The earthquake caused seismic uplift from 0.5 to 6.4 m along 130 km of coastline and resulted in widespread die-offs of important flora and fauna and permanent losses to critical habitats.

There was much concern for the fate of diverse intertidal and subtidal communities, which include culturally and commercially important fisheries, such as pāua, and other habitat-forming species like bull kelp.

Shore-based and dive surveys tracked the abundance of over 120 marine species at 16 sites for more than six years. Findings depict major physical and ecological changes over time across sites.

The complex dynamics of recovery are described in detail in this report and clearly show that the effects from this disturbance to the Kaikōura coastal ecosystem are both significant and ongoing.

This long-term study is the first of its kind and provides a detailed data set and quantitative baselines that will help inform future coastal management decisions.

This report presents an assessment of the orange roughy stock off the west coast of the South Island (ORH 7B) in 2020. There was a fishery from 1985 to 1992, with the TACC peaking at 1708 t between 1989 and 1995, and the fishery was closed from October 2007. The assessment used two acoustic biomass estimates (2017, 2019) and a 2019 age frequency, completely rejecting the assumptions used in previous assessments that CPUE was directly proportional to biomass and that recruitment followed the assumed recruitment curve. This assessment is considered preliminary as work was stopped due to the conclusion that the acoustic surveys had probably missed a substantial proportion of the spawning biomass.

This report provides a 2020 update of 2014 and 2017 assessments of the East and South Chatham Rise orange roughy stock, to enable an HCR-derived recommended catch limit for 2020–21. Three age-structured Bayesian population models were fitted to biomass and composition data. Virgin biomass (B0) was estimated as 300 000–350 000 t and 2020 stock status from the base case model was 36% B0 (± 95% CIs of 30 to 41%). With a vulnerable biomass of 157 000 t, the HCR-derived recommended catch limit was 6348 t for 2020–21, with a slowing increasing population over future years.

Jack mackerels (JMA) support significant commercial fisheries in New Zealand, with over 75% of the total jack mackerel catch taken by trawl fisheries off the west coasts of the North Island and South Island, in JMA 7. Three jack mackerel species are found in New Zealand waters, namely Trachurus declivis, T. murphyi, and T. novaezelandiae.

New Zealand commercial catches of jack mackerels have been recorded under the general code JMA. Therefore species-specific catch information is not available from the fishery data. Estimates of proportions of the three Trachurus species in the catch, based on observer data which includes separate codes for each species, are essential for assessment of the individual stocks.

This report updates the data collected by the New Zealand observer sampling programme from trawl landings of jack mackerels in JMA 7 with the data collected during the 2021–22 fishing year, including estimates of species proportions and sex ratios in the landings, catch-at-length (fork length, cm), and catch-at-age for these species.

Estimated proportions of catch by species based on observer data have historically shown that T. declivis comprises 61–73% of the catch for all statistical areas, followed by T. novaezelandiae at 21–33%, and T. murphyi at 2–8%. In 2021–22, proportions of T. declivis, T. novaezelandiae, and T. murphyi were 77%, 23%, and less than 1%, respectively.

Sampled sex ratios of T. declivis and T. novaezelandiae were close to a sex ratio of 1:1 in the 2021–22 fishing year, and sex ratios for T. murphyi were biased towards females (56%) in 2021–22.

Trachurus declivis and T. novaezelandiae fish in the observer data indicated decreasing proportions of larger and older fish in the commercial catch in recent years, whereas the length and age data for T. murphyi indicated the catch mainly comprised large, older fish, with little evidence of younger fish coming through.

This report presents the results from the 16th inshore trawl survey in a time series started in 1992 along the west coast of the South Island, from Farewell Spit to the Haast River mouth, and in Tasman Bay and Golden Bay.

The survey covers depths from 20 to 400 m (core strata) and surveys many species but is mainly focused on giant stargazer, red cod, red gurnard, spiny dogfish, and tarakihi. Since 2017, two additional strata have been surveyed in 10–20 m in Tasman Bay and Golden Bay to cover the full distribution of snapper in the geographic area.

Data collected include length, weight, and maturity data for selected species, and collection of otoliths (fish ear stones) of the key species for ageing. The trawl survey provides time series of relative biomass estimates and age, length, and maturity stage information used for stock assessments and fisheries management advice for key inshore species.

In 2023, 58 phase one stations were successfully completed in the core strata and another six were carried out in strata 20 and 21. Four phase two stations were completed to reduce the coefficient of variation for spiny dogfish and snapper.

Biomass estimates (in tonnes) for the target species in the core strata were: giant stargazer, 915 t; red gurnard, 1498 t; red cod, 69 t; snapper, 3633 t; spiny dogfish, 3043 t; and tarakihi, 493 t.

The snapper biomass (core strata plus the 10–20 m strata) was the highest ever in the time series and nearly triple that from the previous survey in 2021, with most fish 20 years or younger. Juvenile snapper were caught mostly in the 10–20 m strata. These strata provide important information on future recruitment and contain a variable proportion of the adult population.

A catchability analysis of the survey indicates that the survey can be considered representative of the time series.

Photo surveys are used to estimate abundance of scampi in New Zealand and provide important information for stock assessments.

Readers identify features in the survey photos as burrows or scampi. A statistical model is applied to produce an estimate of abundance for each survey. The statistical model takes into account differences between readers’ interpretation of features (what looks like a burrow to one reader may not to another) and differences in interpreting features over time (e.g., a reader may become more skilled at interpreting features over time, or technology could improve).

This report provides a review of the statistical model applied to produce an estimate of abundance from scampi photo surveys. The review found no concerns with the model or how it is being applied. Two readers re-read images from recent survey years to test if the adjustment over time has been appropriate. The results of the re-reads supported the model results.

Further work is suggested, including contracting a specialist statistician to provide greater theoretical understanding of the model and assumptions.

South Island recreational blue cod fisheries are monitored by Fisheries New Zealand using potting surveys to assess the status of the stocks. The results of the Foveaux Strait surveys are important inputs for full quantitative stock assessments conducted for BCO 5 every five years.

This report describes the results of the random-site blue cod (Parapercis colias) potting survey carried out in Foveaux Strait in February 2023—as well as for three previous surveys (2010, 2014, and 2018). Estimates are provided for population abundance, size structure from fish length, and age structure from otoliths (ear bones collected for ageing), as well as population sex ratio, total mortality, and fishing mortality.

The overall weighted mean length of blue cod in 2023 was 32.0 cm for males and 28.5 cm for females, and mean age was 5.9 years (1–11 years) for males and 6.2 years for females (1–16 years). There were no clear age class modes in 2023 and little evidence of spawning activity during the survey.

The scaled length frequency distributions and mean length of all blue cod were similar for all four surveys, although, in 2023, the proportion of small males was less than in previous years.

Survey abundance (total blue cod mean catch rate) from the four surveys significantly increased between 2010 and 2014, with no change in 2018, followed by a significant decline of 57% in 2023.

The proportion of pots with no catch was similar for the first three surveys (25 to 32%), but in 2023 this increased to 49%. There were no trends in sex ratio over the time series which was around 50% male.

The age structure was similar among the four surveys with most fish between 4 and 8 years of age and relatively few fish over 10 years, particularly males. The fishing pressure is concentrated on just a few older cohorts, some of which are poorly represented.

Relative to the target reference fishing mortality of F=0.15 for blue cod, the estimated mortality in 2023 was nearly seven times higher, indicating that overfishing is occurring. Fishing mortality was also considerably higher than the target for all three previous surveys.

Ling (Genypterus blacodes) is an important commercial fish species in New Zealand middle depths waters and is caught mainly by bottom trawls, bottom longlines, and increasingly by potting.

This report summarises the 2023 stock assessment of one of the five main ling stocks managed under the Quota Management System: the ling stock off the west coast of the South Island (LIN 7WC).

A stock assessment model was carried out, based on commercial catches, information from the west coast South Island Tangaroa trawl survey biomass series, the commercial longline standardised catch per unit effort (CPUE) from 1991, and the commercial trawl standardised CPUE from 1997.

The initial spawning stock biomass (B0) for both the base case model was estimated to be about 62 200 t and stock status in 2023 was estimated as 51% B0. An investigative model run provided a slightly lower initial biomass and stock status in 2023 of 52%.

Five-year projections were done using the base case model, resampling recruitment from the entire range of the model, and assuming future annual catch equal to the average catch in 2020–2022. Projected stock status in 2028 was expected to be 52% of B0.

The probability that the stock status in 2028 will be above 40% B0 was 97%, and that of being less than 20%, was zero. This assessment was used to inform Fisheries New Zealand’s management of this ling stock.

Catch-at-age data are important for the stock assessment of fish species because they provide information on the strength and progression of age classes in the stock, including juveniles and fish that are large enough to be taken by commercial fishers. These data include information on fish length and age (from otoliths—the ear bones of fish) collected at sea by observers from the commercial catch.

This report provides analyses of catch-at-age from the bottom trawl fisheries for barracouta (Thyrsites atun, BAR) in BAR 5 (Southland) and for gemfish (Rexea solandri, SKI) in SKI 3 (southeast coast) and SKI 7 (Challenger) for the 2021–22 fishing year. These results are the second of a three-year catch-at-age series for these two species.

Data for the 2021–22 season included few barracouta under 60 cm, indicating either less fishing on smaller (and younger) barracouta, or a poor year class should be expected. Most of the barracouta were aged 2–5 years.

Gemfish from SKI 3 in the 2021–22 fishing year showed a range of fish sizes, with most between 45 and 52 cm, which corresponded to age 2 fish, and also at sizes that corresponded to ages 4–6.

Gemfish from SKI 7 were less variable in length and included some fish under 50 cm, mainly females, which corresponded to ages 0–1. Most of the gemfish in SKI 7 around 50 cm in length corresponded to age 2; this was a strong cohort, particularly for males. Females were generally larger (and older) than males in the bottom trawl catch, with a strong mode at ages 5–8 for the females.

A stock assessment survey of Foveaux Strait oysters (OYU 5) in February 2023 found numbers of commercial-sized, recruit, pre-recruit oysters, and small oysters had decreased by between 44.8% and 52.3% from 2022 numbers. Winter-spring disease mortality is the most likely cause. These decreases cannot be fully explained by fishery and survey data. Summer mortality from Bonamia increased from 5% in 2022 to 9% in 2023. Mostly large oysters died; 70% of oysters are below recruit-size. Spat settlement was high.

This report updates and summarises the observational and research data for southern blue whiting from 1990 to 2022. These data include the time series of relative abundance from acoustic surveys, trawl survey indices, and updated time series of length-at-age and catch-at-age from observer sampling of commercial catch.

For the Bay of Plenty base model run current biomass was estimated to be 68.4% B0 (median), with 95% credible interval 46.6–97.7% B0. For all five-year projection scenarios, there was a low probability that the target biomass would decline below the target level of 40% B0. A stock assessment was also attempted for a Ninety Mile Beach/East Northland/Hauraki Gulf stock, but was unsuccessful due to conflicts between the abundance and catch-at-age data.

Fisheries stock assessments were undertaken for SCI 1 and SCI 2. The SCI 1 assessment was rejected by the Fisheries New Zealand Deepwater Working Group due to sensitivity to the trawl survey catchability prior. The SCI 2 assessment was accepted, but with a lower quality rating due to unresolved conflicts in data inputs. For SCI 2 current status in 2022 was estimated to be 56% B0 and likely within 47–66% B0. Projections were not carried out with either assessment.

This study used a model of individual eco-physiological response to environmental and climate factors to derive population level outcomes of fish stocks. These simulations were used to investigate how fisheries stock assessments are influenced by climate and bottom-up variability in production parameters. The assessments generally provided unbiased estimates of stock status even though there were annual and decadal fluctuations in all production-related parameters.