Fisheries management services

Managing a successful fishery is a task that requires meeting the expectations of anglers whilst ensuring that the needs of the fish and the wider aquatic ecosystem are met. This is certainly not easy and with so many factors that need to be considered things often do not go according to plan.

Should you encounter an issue that you would like help resolving, or require advice with regards to making improvements, Thomson’s fisheries scientists are here to help. As full members of the Institute of Fisheries Management our staff are perfectly placed to offer a range of advice and services in helping you run and maintain a successful recreational fishery.

Stock assessments and cropping

Stock management is critical to ensuring fish remain healthy and continue to grow. Fish within an overstocked lake are susceptible to infection and will likely not feed as frequently due to high stress levels. Low stocking densities can result in fewer fish being caught, although higher growth rates can often be achieved in such circumstances.

Making the correct stock management decisions for any fishery relies on accurate data. Without knowing the number of fish within a fishery, the numbers of each species, or the size of fish present and their growth rates, it is impossible to make an informed judgement as to whether fish should be removed or added to the current stock.

Thomson’s fisheries scientists carry out stock assessment surveys of fisheries in order to obtain the crucial information needed to make these critical decisions. We deploy a variety of survey methods (including netting and electric fishing) that enable us to calculate the stocking densities and species compositions of a wide variety of fisheries.

We are also able to calculate accurate growth rates for fish through the analysis of weight, length and fish age data. Fish age is calculated by analysing scales under a dissecting microscope. This process can also shed light on periods of stress and/or disease.

Water quality monitoring

Good water quality is critical for healthy fisheries and ecosystems. Poor water quality is likely to stress fish, resulting in increased susceptibility to disease and decreased growth. It will also reduce the amount of natural food available to fish and can lead to algal blooms and excessive weed growth.

Thomson Ecology’s fisheries consultants are able perform a wide variety of in-situ tests that measure dissolved oxygen, pH, ammonia, nitrite, nitrate, general/temporary hardness plus other tests as required. We monitor all water quality parameters with the use of highly accurate probes. We interpret all results from a fisheries/aquatic ecosystem perspective and, if necessary, make practical recommendations as to how water quality can be improved to match the optimum growth conditions of various fish species.

Weed and algae management

We regularly provide expert advice on the control and removal of problematic weed from recreational fisheries. Once the severity and cause of the increase in weed/algae abundance is established we are able to recommend and carry out the most appropriate method of control for your fishery. Options include various ways of reducing nutrient input and lowering rates of photosynthesis.

Algal blooms vary greatly in terms of their impact on fish and ecosystem health. If your fishery experiences an increase in algae abundance, then we recommend that you provide us with an initial sample to determine if the bloom is comprised of potentially toxigenic algae. Should quantitative analysis of an algae sample be required an algal identification and enumeration can be performed. Counts can be performed on only a single group of algae (i.e. cyanobacteria) or on the entire algal population.

Should quantitative analysis of an algae sample be required an algal identification and enumeration can be requested. Counts can be performed on only a single group of algae (i.e. cyanobacteria) or on the entire algal population. Results for each species are recorded in natural units/ml (cells, colonies, filaments) and cells/ml. Numbers for each group of algae (i.e. diatoms, green algae, cyanobacteria) are tallied as well as the total sample cell density. If desired, biovolume estimates can also be made.

Aquatic macrophytes

Aquatic macrophytes are large, easily visible plants that occur in or near water. They include submerged, emergent and floating flowering plants as well as ferns and bryophytes. A suitable planting scheme is critical to creating a successful sports fishery. Aquatic macrophytes provide shelter, spawning substrate, oxygen, and food for fish. Thomson works with trusted suppliers of aquatic plants to provide you with a range of native species that, when planted in suitable densities and locations will greatly enhance your fishery.


Disease and Invasive Non-Native Species (INNS) can have a devastating impact on a fishery in terms of financial loss, damage to reputation and poor fish health. Whilst the risk of disease can never be eliminated it is possible to greatly reduce the likelihood of an outbreak occurring through the implementation of biosecurity measures.

Thomson’s fisheries consultants have reviewed biosecurity at a number of high-profile fisheries in the UK. Working alongside fisheries owners we can identify areas of risk and implement measures to help ensure fish remain disease free. If your fishery could benefit from a thorough biosecurity review then please get in touch. All biosecurity reviews include a site visit and a written report containing recommendations.


Thomson’s fisheries team members have delivered fisheries management courses at some of the most well respected educational and professional institutions in the UK. Staff who are full members of the Institute of Fisheries Management (IFM) and hold relevant training qualifications deliver training courses to fisheries management professionals and angling club members.
The courses we deliver cover

  • stock management
  • aquatic ecology
  • biosecurity
  • fish health and biology
  • water quality
  • predation.

Our courses run on a regular basis so please get in touch to reserve a place. If your organisation has a specific training need then Thomson would welcome the opportunity to assist. Please contact us today!

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