Fisheries Monitoring and R&D

Fish monitoring – an overview

Enable effective fisheries management

The monitoring of fish can be used to determine when and how fish are moving within river corridors, the link between such movements and biotic and abiotic factors, quantification of fish populations and assessments of fish behaviour. Fishtek can provide a wide range of techniques for monitoring fish populations in both freshwater and marine environments.

This monitoring can be carried out for a discrete period of time within one year, e.g. a period of a few days, or a few weeks or over multiple years to help determine how a population is changing. While the Fishtek team have the most experienced in the monitoring of fish migration and in-river movements, we have carried out monitoring in a wide range of areas in the past.

Fish Surveys

Surveys of fish populations are carried out to determine the current state of a fish population (or populations) and this information can then be used to help inform policy and management.

In addition to electro-fishing, we are able to carry out surveys using a variety of netting techniques. A few examples of previous projects that we have been involved in include surveys of eel populations in drains on the Somerset levels, an assessment of fish stocks in a large lake using seine-netting and fyke-netting, an assessment of the mortality incurred by fish passing through a pumping station.

Monitoring of fish migration and passage

Fish migration analysis

Determining when and how many fish are migrating is a key component of effective fish pass design as this data can help to ‘fine tune’ the specific design of a fish pass and determine how fish are interacting with an in-stream barrier.

Equally, knowledge gained from this kind of monitoring can help to inform the management of a fish population. Fishtek have carried out a large number of monitoring studies in the past investigating the migration and behaviour of fish, including the following:

• Pit-tagging studies to investigate the effectiveness of Low Cost Baffles (LCBs) at improving passage of several different fish species past gauging weirs
• Pit-tagging and camera monitoring to investigate the swimming ability and behavioural responses to flow of wild Mekong fish species
• Camera monitoring at multiple sites to determine use of fish passes by different fish species. Cameras used have included both underwater and over-head monitoring. This has included work to investigate the movement of salmon through a fish pass, downstream migration of fish through screw turbines and timing and scale of migration through natural river channels on the Mekong River
• Monitoring of fish passage at specific fish passes using resistivity counters
• Camera monitoring and resistivity counter monitoring of shad migration at a barrier in the River Severn
• Use of DIDSON and ARIS acoustic cameras to monitor fish behaviour at anthropogenic structures including intake screens, sluices and fish passes. Acoustic cameras can be used to monitor fish behaviour and movements in turbid conditions when optical cameras will not work. Previous projects have included investigations of the behaviour of eels at the intake screen to a pumping station, assessments of sea-trout and salmon migration in a Westcountry river and assessment of salmon migration in response to the release of freshets

Smolt Monitoring

Salmon and sea trout life cycle

Smolts are a key life-stage within the life cycle of salmon and sea-trout and there is increasing evidence that the in-river mortality and loss of smolts is a key contributor to the decline of these species. Fishtek, working in conjunction with the Environment Agency, has designed and fabricated a unique smolt trap that can be employed on small rivers to trap downstream migrating smolt for subsequent counting, measuring and tagging (if necessary).