Assessing fishery resources

NIWA is developing and applying standardised stock monitoring and assessment methodologies for New Zealand's deepwater, inshore, and freshwater fisheries. This will enable better monitoring and prediction of changes in fish population biology, fish stock biomass, and size and age composition.

This programme seeks to ensure fisheries stock monitoring and assessment methodologies are robust, standardised where appropriate, and continually upgraded as new or improved methodologies or technologies become available.

Research to support single-species management on the 96 species under the Quota Management System (QMS) is largely funded through fishing industry levies. The industry plays a key role in the prioritisation and evaluation of the research.

The main focus is to:

  • monitor and assess stocks with the highest landings or value
  • monitor and assess stocks most at risk of being unsustainably fished
  • develop techniques to monitor low value species.

Research directions

Stock structure and population biology

We use a variety of approaches and analyses (e.g., genetics, age and growth characterisation) to better define stocks and to determine important aspects of population biology, for example, stock structure, natural mortality, spawning areas.

Monitoring surveys

The data for these analyses are collected in a variety of ways:

  • trawl surveys. NIWA conducts detailed trawl surveys to collect high quality data for species and environmental monitoring. This is added to existing survey data to continue time series.
  • acoustic surveys. NIWA performs acoustic and photographic surveys from research and industry vessels, and continues to develop acoustic and camera technology to further improve monitoring capability for species.
  • fishing method surveys. NIWA is continuing to add to existing time series and is developing new survey methods to monitor potting, dive, and recreational fishing.

Catch sampling

Important information is obtained by taking samples of fish caught in commercial and recreational fishing activity.

Non-commercial fisheries

NIWA is developing approaches to monitor and assess recreational, freshwater, and customary fisheries.


NIWA will be further developing ageing methodologies (and standardised protocols) to validate age estimates based on analysis of body structures such as, vertebrae, spines, shells, and otoliths (a bone in the inner ear).

Population Modelling

NIWA is updating and developing routine stock characterisation and stock assessment models (e.g. size and age frequency distributions, catch-per unit-effort) , using standardised techniques and software for fisheries analyses, assessment, and prediction.

We are also developing methods for a wider ecosystem approach (considering the interrelationship between different species and environments) and to appropriately incorporate sources of uncertainty in stock assessment or ecosystem models.