Guidelines for sampling freshwater fisheries

We have prepared a breakdown of the different guidelines that are available for sampling freshwater fisheries. The overview provides links to key documents that explain what should be considered when designing fish monitoring studies and how to implement the various sampling techniques.

This is an overview of the guidelines currently available about how to sample freshwater fishes in New Zealand. The overview provides links to key documents that explain what should be considered when designing fish monitoring studies and how to implement the various sampling techniques.

Each of the links are free to access and this overview will be periodically updated as new guidelines become available.

Strengths and weaknesses of guidelines

The guidelines and links outlined below are for researchers wishing to:

  • survey wadeable (<1m deep) streams and rivers
  • quantify fish and collect an index of relative abundance.

The guidelines below will not:

  • generate density data or monitoring population sizes
  • fit all study requirements if you wish to target particular fish species or life-history stages that are difficult to catch.

Related to this, survey methods for non-wadeable streams are not well established for New Zealand, but there are a couple of documents provided at the bottom of the webpage that you can use to read further on this topic.

New Zealand Freshwater Fish Sampling Protocols – Wadeable Rivers and Streams

This guide was designed to improve sampling consistency and ensure comparable data is collected throughout New Zealand.

New Zealand Freshwater Fish Sampling Protocols [9.4 MB PDF]

This guide is especially useful if you are sampling as part of the State of the Environment Monitoring programme. The publication provides guidance on:

  • selecting the most appropriate sampling method (timing and site selection)
  • explaining how to implement the methods
  • use of an electric fishing machine
  • spotlighting and trapping methods
  • recording and analysing data.  

Department of Conservation freshwater fish inventory and monitoring guidelines

The Department of Conservation has a series of comparative guidelines and decision trees to help researchers select the most appropriate sampling methods.

View the guidelines on the Department of Conservation website  

This webpage contains:

  • an overview of fish monitoring and the use of decision trees to select appropriate sampling method
  • guidelines on how to implement spotlighting, electric-fishing and netting techniques
  • within each fishing method, three different sampling methodologies are explained and there is also some sampling guidelines available specifically for mudfish (Neochanna species).

Guidelines for sampling non-wadeable systems

The guidelines outlined above focus on sampling fishes in wadeable waterbodies (generally shallower than 60 cm deep), but some of the methods can also be used in non-wadeable areas such as lakes and estuaries.

There are not many resources currently available that outline sampling guidelines for these non-wadeable areas in New Zealand.

An example of how fyke nets and traps can be used to sample fishes has been published by Environment Southland.

Environment Southland: Fish Surveys in Non-wadeable Systems [938KB PDF]

If you want to read about non-wadeable stream sampling guidelines used overseas you can find the guidelines developed by the United States Environmental Protection Agency.

United States Environmental Protection Agency: Concepts and Approaches for the Bioassessment of Non-wadable Streams and Rivers [32KB PDF]


If you have any further questions about sampling methodology please use the contacts provided within the documents outlined above, or you can email your questions through to the Freshwater Database administrator, contact details below.

Related information

Read about New Zealand tuna (eel) sampling methods 

Electric fishing machine training  

If you require certification for the use of an electric-fishing machine, NIWA provides training courses on this sampling technique. Please contact training enquiries to express your interest in doing one of our electric-fishing machine operator’s courses, contact details below.