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.

This report presents results of the 2022 inshore trawl survey of the west coast North Island (WCNI), the 9th in a time series starting in 1989, but with a 19-year gap between 1999 and 2018 surveys.

The survey extends from Scott Point on Ninety Mile Beach to Mana Island covering a depth range from 10–200 m north of Cape Egmont and 10–100 m to the south. Since 2018, there has been no sampling within 2–4 nautical miles of the coast between Maunganui Bluff and the Waiwhakaiho River, New Plymouth, a no-trawl area established to protect the Māui dolphin.

Everything that is caught in the trawl is sorted, identified, and weighed, and length and maturity data are collected for selected species and otoliths (fish ear stones) for ageing the four main species of interest: snapper, red gurnard, John dory, and tarakihi. 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, 95 phase one stations were successfully completed followed by four phase two stations completed to improve the coefficient of variation for tarakihi.

There were 72 species recorded in total, with snapper by far the most abundant. Biomass estimates (in tonnes) for the key species across the whole survey were: snapper, 8396.3 t ; red gurnard, 1160.5 t; tarakihi, 447.6 t ; John dory, 305.3 t.

The 2022 snapper biomass estimate was lower than that from the 2019 and 2020 surveys, but still significantly higher than the historical surveys in the 1990s. There were high numbers of juvenile snapper under 5 years old but a lower number of adult fish. The variability in adult snapper biomass in this survey may be due to fish moving inshore into shallow water to spawn, or may reflect the highly patchy distribution of snapper at this time of year.

The biomass estimate for adult red gurnard was relatively stable, but the biomass of smaller fish was substantially below historical estimates.

Last updated: 12 April 2024

Snapper are the most important recreational fish species in New Zealand and are often released back to the sea after capture.
Little is known about the survival of fish after they are released.
NIWA conducted a study using volunteer fishers to catch 960 snapper at different depths and with different hook placements.
The captured snapper were kept in holding nets and monitored by NIWA divers over several days.
Fish hooked in the lip had a low chance of dying if caught at shallow depths, but the chance of dying increased as depth increased.
Fish hooked elsewhere on the body had a higher chance of dying, with those hooked deep in the gut having the highest chance of dying.
This study suggests that fishing practices can impact fish survival, but there are ways to potentially reduce post-release mortality.
Understanding how fishing affects fish survival is therefore an important consideration for catch and release fisheries and when setting catch limit regulations.

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.

National Chemical Residues Programme Results for 1 July 2022 – 30 June 2023 and the programme for 1 July 2023 – 30 June 2024 for farmed cattle, sheep, goats, deer, pigs, ostriches, honey, salmon, poultry, wild mammals, and fish.

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.

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.

Rig nursery grounds were defined and ranked from a review of existing information and a nationwide set net survey of 14 major harbours and estuaries in 2011. Kaipara and Raglan harbours were very important nurseries, followed by Waitemata, Tamaki and Porirua harbours. South Island harbours do not appear to be important rig nurseries. Juvenile snapper and grey mullet were frequent bycatch in North Island estuaries, and were most abundant in the same harbours as rig.

This report describes relationships, patterns and contrasts in benthic species composition, assemblages and habitats, both within and between sites and initial sampling strata across the Challenger Plateau and Chatham Rise. Data used came from four different fauna collection methods: DTIS video; seamount sled; still images taken along the DTIS video; and beam trawls.

A 2013 workshop Future proofing New Zealand’s shellfish aquaculture: Monitoring and adaptation to ocean acidification, brought together experts from government, the aquaculture industry and science organizations from the US and NZ to raise awareness of ocean acidification within the NZ aquaculture community, identify ways to protect the aquaculture industry and develop US-NZ scientific cooperation to address OA. Papers presented at the workshop and points raised during discussion are summarised.