The study summarised diets of top predators in New Zealand waters and estimated the spatial-temporal distribution of many of their prey species caught in inshore fisheries. These were consistent with previous estimates and with existing information and could be used as inputs in other processes such as spatial risk assessment models. Care should be taken for species such as squid or hoki where only the shallow part of their range was included and species groups such as jack mackerel or rattail.

This project developed a food-web model to explore the potential ecosystem effects of changes to small and medium-sized pelagic fish (including jack mackerels, anchovy, pilchards, sprat, yelloweye mullet, blue mackerel, yellow-tailed scad/kōheru) in the Hauraki Gulf. We found that the response of the ecosystem to changes in the abundances of pelagic fishes depended strongly on the extent to which top predators (seabirds, whales/dolphins, fish) are flexible in their diets.

The sixth trawl survey off the west coast South Island (WCSI) was completed August 2021. Species monitored by the trawl survey include hake, ling, and a range of other species. Ling biomass declined to the lowest of the series, while hake increased. As well as supporting the stock assessments for hake and ling, the trawl survey provides information on a number of bycatch species. A total of 208 species or species groups were caught and 25 845 fish or squid of 64 different species were measured.

An updated risk assessment was conducted for 54 New Zealand marine mammals using a multi-species spatially explicit risk assessment. Goodness-of-fit assessments indicated reasonable performance to predict total number of captures for pinniped and delphinid species with >5 captures, but poor performance to predict the spatial location of those captures. Poor performance may be due to inappropriate structural model assumptions or to biological inputs. Results should be interpreted with caution.

This report describes the results of the blue cod (Parapercis colias) random-site potting survey carried out in Marlborough Sounds in October 2021. Estimates are provided for population abundance, size and age structure, sex ratio, total mortality (Z), and spawner biomass-per-recruit ratio. This is the third full random-site blue cod survey carried out in the Marlborough Sounds and the tenth survey overall, with nine fixed-site surveys carried out between 1995 and 2017.

This report describes the results of the blue cod (Parapercis colias) random-site potting survey carried out in Marlborough Sounds in October 2021. Estimates are provided for population abundance, size and age structure, sex ratio, total mortality (Z), and spawner biomass-per-recruit ratio. This is the third full random-site blue cod survey carried out in the Marlborough Sounds and the tenth survey overall, with nine fixed-site surveys carried out between 1995 and 2017.

Commercial purse seine landings of Trachurus novaezelandiae from the Bay of Plenty purse seine fishery were sampled from length and age throughout the 2019–20 and 2020–21 fishing years. Catch curve total mortality estimates derived from the resulting age distributions suggest that levels of fishing mortality were sustainable in the areas fished. Age-length and length-weight parameter estimates are also provided by this report; these should be used instead of existing estimates for this species.

This report describes the results of the random-site blue cod (Parapercis colias) potting survey carried out off Banks Peninsula in April 2021. Estimates are provided for population abundance, size and age structure, sex ratio, total mortality (Z), and spawner biomass-per-recruit ratio. In addition, results are presented for surveys carried out in two Banks Peninsula marine reserves (Pohatu and Akaroa).

Researchers took data from a long-term experiment on elevated atmospheric carbon dioxide (CO2) impacts on grassland and applied them to a real farm. They used an ecosystem model and a farm system optimisation model to compare the current farm with the farm in the future under elevated CO2. The future farm made more profit but required more P fertiliser, greater management input and had higher farm total greenhouse gas emissions. The next stage should be to run the farm with climate as well as CO2 changes.

Keywords: FACE, climate change, impacts, elevated carbon dioxide, APSIM, AgInform

This report summarises the Sub-Antarctic hake (HAK 1 south of 46° S) fishery with spatial structure of the stock, biological parameters, and standardised catch per unit effort (CPUE). The CPUE indices were similar for the tow-by-tow data and the daily summary data and showed a similar trend to the Sub-Antarctic trawl surveys. In general, the CPUE indices had declined over the period of fishing but had levelled off in recent years as the total catch declined.

Changing what we eat is one of the most effective ways to lower our carbon footprint Food production has a significant carbon footprint. Farmed shellfish have the potential to be a low-impact part of our diet. They are nutritionally rich, high in protein, and can be grown without supplementary feeds – taking what they need to develop directly from the water column.

This report updates the 2009 report Economic Costs of Pests to New Zealand. The report assessed the total economic costs of pests to New Zealand, both defensive expenditures and output losses. The report will be used to support the review of the Biosecurity Act, and provides information to support other Departments, regional councils, and primary sector industries to understand the impacts of pests.

A roving-access survey design is proposed to estimate the harvest of pāua (Haliotis iris) by amateur fishers. There are multiple access points from a coastal highway. The survey uses an instantaneous count of potential pāua gatherers in the water during a transit of the coast, to provide an estimate of total effort in each spatial and temporal stratum, and a separate concurrent on-site access survey to conduct interviews of fishers at the completion of trips to estimate catch per unit effort.

A simulation testing framework was developed to evaluate and compare the performance of harvest control rules (HCRs) for 4 scampi stocks SCI 1, SCI 2, SCI 3, and SCI 6A. The harvest control rule evaluation (HCRE) framework uses CASAL stock assessment models as operating models and projects the simulated populations forward by applying an HCR each year to determine total annual catch. The framework is generalised and can be used with any CASAL model that has at least one CPUE index to project.

This project developed a soil organic carbon (SOC) monitoring framework and a method for estimating SOC, total nitrogen stocks, and stock changes at national scales. The method is designed to monitor soil carbon stocks and stock changes through time for a specified land use, to track the effect of management and/or climate change impacts on the soil carbon and nitrogen resource. The method could be implemented on managed agricultural land on flat-rolling topography.