Grüss, A.; Datta, S.; McGregor-Tiatia, V.; Holmes, S.J.; Davis, J.P.; Fulton, E.A.; Sainsbury, K.; Plagányi, É.E; Dolder, P.J.; Parsa, M.; Dambacher, J.M.; Gaichas, S.K.; Townsend H.; Pascoe, S.; Blanchard, J.L.; Parsons, D. (2025). Towards ecosystem-based fisheries management in New Zealand: an ecosystem approach to fisheries management case study in FMA 7. New Zealand Aquatic Environment and Biodiversity Report No. 360. 80 p.

Aotearoa New Zealand has committed to progress integration of broader ecosystem and environmental considerations in fisheries management. These efforts can start with an ecosystem approach to fisheries management, where these broader considerations are explicitly considered in analysis focused on management settings for individual fish stocks.

The research reported here identified and reviewed tools that could support greater analysis of ecosystem and environmental considerations in New Zealand’s current fisheries management framework.

The Fisheries Management Area 7 (west coast South Island) inshore mixed bottom trawl fishery was used as a case study for this research. Meetings with managers and key fishery stakeholders were held to establish key management questions around ecosystem and environmental considerations. This included understanding the effects of single species catch limits on other species in a mixed fishery, the ecosystem effects of environmental stressors such as sedimentation, and key predator-prey interdependencies. An international expert workshop was then held to identify tools which have been applied overseas to inform management advice on ecosystem and environmental considerations for fisheries.

There exists a diverse range of ecosystem simulation models, with different configurations, levels of complexity, information requirements, and management applications. Qualitative ecosystem models and ecosystem models of intermediate complexity are the most suitable ecosystem simulation models to assist the ecosystem approach to fisheries management in New Zealand, primarily because of their more limited data requirements and their ability to strongly engage resource managers and other stakeholders. Beyond ecosystem simulation models, tools called “métier analysis”, “principal component analysis” (“PCA”) and “heatmaps” provide additional technical options for supporting the ecosystem approach to fisheries management in New Zealand.

Our report also includes recommendations to facilitate the inclusion of ecosystem and environmental considerations in resource management, which were provided at the international expert workshop, and directions for future research.

Paul-Burke, K.; Burke, J., Gerrity, S. (2025). Piri Pāua: Mātauranga Māori and marine science approach to growth rate and length of maturity of pāua in the Bay of Plenty, 2022–2024. New Zealand Fisheries Assessment Report 2025/28. 20 p.

Pāua is a highly regarded taonga (culturally important) species. Mai i ngā Kurī ā Whārei ki Tihirau (the Bay of Plenty Regional Iwi Customary Fisheries Forum) raised concerns about the current state of pāua in Te Moana-a-Toi (Bay of Plenty). This project utilised localised intergenerational observations of population dynamics in traditional harvesting areas to assess pāua productivity in the Tauranga Moana Mātaitai Reserve in Tauranga and Te Rohe Moana o Ngāti Awa in Whakatāne. The project combined mātauranga Māori alongside marine science field methods.

Results were compared with previous iwi-led research at Tauranga in 2013 and Whakatāne in 2010. The pāua population in 2023 had declined by almost half in Tauranga but remained relatively consistent across all sites in Whakatāne. However, pāua were small sized in both locations, with less than 1% of individuals reaching the Minimum Legal Size (125 mm) for harvesting. Growth rate surveys were conducted in the wild at both locations from June 2023 to the end of May 2024 and identified pāua as slow growing and, as a result, sexually mature at smaller sizes than in other regions of Aotearoa New Zealand.

People in New Zealand enjoy the collection of seafood as a recreational and customary activity along the country’s coastline. Two important seafood species in coastal areas are cockles and pipi, which occur in intertidal sediments of beaches, estuaries, and large tidal inlets and harbours. In northern New Zealand, cockles and pipi have been regularly monitored for several decades across different sites in Northland, Auckland, Waikato, and Bay of Plenty. This monitoring aims to ensure the persistence of their populations, providing information of the abundance, density, and population size structure of cockles and pipi. Presented here are the survey findings from the summer of 2024–25, with population information for Pataua Estuary (Northland), Cockle Bay, Kawakawa Bay (West), Mill Bay, Ōkahu and Okoromai bays (Auckland and its wider region), Ōhiwa Harbour, Otūmoetai (Tauranga Harbour), and Waiotahe Estuary (Bay of Plenty), and Whangapoua and Whitianga harbours (Waikato). Both cockle and pipi populations across these northern sites were generally large, consisting of millions of individuals. Their densities varied dependent on the site, but were a minimum of over 140 individuals per square metre for cockles, and over 180 individuals per square metre for pipi, except at one site (Pataua Estuary). At several sites, small-sized individuals made up most of the population, highlighting strong recruitment events that preceded the data collection.

The aim of this project was to estimate the extent of the spatial area that was commercially fished for longfin and shortfin eels in the South Island from 2020 to 2023. For longfin only, this was compared to the previous estimate of all habitat to provide an update of the proportion of longfin habitat that is fished commercially. This provides an indication of the spatial fishing pressure that both longfin and shortfin eel species have experienced and can be used as a tool to assess the status or health of eel stocks.



From 2020 to 2023 there were 1851 eel fishing events of approximately 15 fyke nets set per event, from 21 fishers. About half of the eel fishing events were from lakes and half from rivers. Most fishing on rivers was from the riverbank where the target species was longfin, and most lake fishing was vessel-based where shortfin were targeted. Nearly three-quarters of longfin fishing events and half of shortfin events were in Southland, Otago, and Westland, with most of the remaining shortfin effort focused on Te Waihora (Lake Ellesmere) and Lake Brunner.



A total of 3714 unique river reaches (totalling approximately 2700 km) were fished over the four years. Half the river reaches were fished only once in the four years, with a fifth of the reaches fished more than four times. The total area fished for longfin in the South Island from 2020 to 2023 was 55.4 km2 and for shortfin was 42.7 km2. Of the total current longfin habitat in rivers, and in lakes accessible to longfin in the South Island, about 14% is currently fished. Compared to the previous estimate of the proportion of longfin habitat fished in 2016, the current estimate has declined by about 20% reflecting a substantial drop in fishing effort in recent years.

Presented in this report are standardised catch per unit effort (CPUE) analyses and fishery characterisation for the South Island commercial freshwater shortfin and longfin eel fisheries for the years 1991 to 2023. The fisheries within nine catchments or management areas that are commercially fished are described along with trends in abundance of both eel species, where sufficient data exist, over this 33 years period.

The main South Island longfin commercial fisheries are concentrated along rivers in Otago, Southland and Westland and the main shortfin fisheries are focussed on coastal lakes and river mouths such as Te Waihora (Lake Ellesmere) and Lake Brunner.

Before introduction into the Quota Management System in 2001, shortfin abundance indices showed clear declines for Otago (AV) and Southland (AW), but in Westland (AX) there was an overall increase in abundance. After 2001 there were slight increases in shortfin abundance in AV and AW and a clear increasing trend for AX. Te Waihora (AS1), after 2001, showed a steep increase in abundance before levelling off for a few years, followed by a fast and steep decline after which it was variable with no clear trend.

Shortfin stock status is as follows:
AV and AX - No target has been set for shortfin, but stock status is unlikely (<40%) to be below the soft limit.
AW - No target has been set for shortfin, but stock status is about as likely as not (40–60%) to be below the soft limit.
AS1 - Unlikely to be at or above the target Bmsy for shortfin, but unlikely (<40%) to be below the soft limit.

Longfin abundance showed clear declines before 2001 for AV and AW, but in AX it progressively increased over time. After 2001 abundance for AV and AW was generally stable but with increasing trends in recent years, whereas AX showed an overall trend of increasing abundance.

Longfin stock status is as follows:
AV and AX - No target has been set for longfin, but stock status is unlikely (<40%) to be below the soft limit.
AW - No target has been set for longfin, but stock status is very unlikely (<10%) to be below the soft limit