Aquatic Ecology surveys and advice for all freshwater environments

Fisheries and Fish Ecology


Catchment Walkover Surveys

Aquatic Ecology Surveys

We offer aquatic ecology surveys and services for all freshwater environments, with experience of operating throughout the UK and abroad.

Our ecological surveys are conducted in accordance with the latest industry standards and best practice, whilst adhering to our stringent health and safety protocols. We offer a multidisciplinary service drawing from our aquatic ecologists’ expertise in fisheries and fish ecology, macro-invertebrates, macrophytes, habitat surveying, water quality assessments and hydrographic surveying. Each of our aquatic ecologists is trained and accredited to work on or near water and understands the need for biosecurity, to prevent the spread of non-native invasive species.

With many years’ experience working in aquatic environments, we are well placed to provide cost-effective advice and to deliver the aquatic ecology survey services outlined below.

Brown trout within River Test

Our aquatic ecologists provide freshwater ecological surveys for rivers, lakes and streams (pictured: Brown trout Salmo trutta)

Fisheries and Fish Ecology

Carcinus provides a wide range of fish ecology survey, monitoring and analysis services. Our fisheries scientists have many years experience in the collection of robust fisheries data from freshwater environments throughout the UK and abroad.

Fisheries Habitat Walkover Surveys

Our fisheries ecologists undertaken fisheries habitat walkover surveys within river catchments and typically include the main river channel and any tributaries (including permanently wetted drainage areas that may be used as fish refuge).


Our experienced freshwater ecologists deliver macro-invertebrate surveys for freshwater aquatic environments.

The community composition and abundance of macro-invertebrates within freshwater environments provides a valuable indicator to the health of a waterbody and its water quality.

Catchment Walkovers and Ecological Assessments

Our ecology staff undertake ecological walkover surveys within river catchments and at standing waters to identify, map and classify aquatic and riparian habitats that are utilised by priority species. Surveys are undertaken utilising the River Habitat Survey (RHS) classification system or Lake Habitat Surveys (LHS) as appropriate.

Client Testimonial

We contracted Carcinus for a project in Leicestershire, to carry out a habitat review for notable SAC qualifying fish species bullhead and spined loach. They carried out a field assessment and provided us with a report that we were able to use as evidence for a Habitats Regulation Assessment, giving Natural England the advice sought. They also helped us with habitat creation and restoration advice which was invaluable. I would recommend them to anyone undertaking works to affect freshwater fish.

Andrew Arnott

Principal – The Ecology Practice

Pragmatic and Proportionate

When planning our aquatic ecology field surveys, we always seek to ensure a pragmatic and proportional approach is taken and full consideration is given to the prevailing knowledge of baseline environmental conditions and the likely environmental impacts of a project. In this way, we deliver cost-effective aquatic ecological surveys that provide the necessary level of information needed to inform a robust environmental assessment and gain the approval of the statutory regulatory authorities.

All our ecology surveys are delivered in accordance with our robust internal health, safety and quality management systems. Staff are fully trained and equipped with the necessary tools and equipment to undertake the tasks required in a safe and efficient manner. All activities are fully risk assessed and a process of continuous review and reassessment ensures that our activities are undertaken in the safest possible way whilst ensuring the highest quality outputs.

More Information

If you would like more information, please view and download our Capability Statements, or read about our recent projects. Alternatively, you can contact us.

Capability Statements

Recent Projects

Freshwater ecologist recording river corridor survey notes

River Habitat Survey & Impact Assessment

Carcinus Ltd was commissioned by Hampshire County Council (HCC) to deliver river habitat surveys and impact assessment consultancy services with a focus on fish ecology in support of a proposed flood alleviation project in Winchester on the River Itchen. The project was in its initial phases and a baseline characterisation of the existing fisheries and fish habitats and initial environmental assessment to inform engineering considerations was required.
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Quantitative lamprey electrofishing survey

Lamprey Survey Population Assessment – River Itchen SAC SSSI

Carcinus Ltd was commissioned by Natural England and the Environment Agency to undertake a catchment wide lamprey population study on the River Itchen, Hampshire. The River Itchen is a designated Special Area of Conservation (SAC) and a Site of Special Scientific Interest (SSSI). The river forms part of Natural England’s “Hampshire chalk catchment” focus area and covers approximately 310 hectares of classic chalk river.
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Barrier to migratory fish migration

Fish Habitat Assessment & Enhancement Study

Carcinus Ltd was commissioned by Hampshire County Council (HCC) to deliver fish habitat assessment surveys and habitat enhancement consultancy services in support of the high-profile Botley Bypass highways project. The project has been permitted after passing through the Environmental Impact Assessment (EIA) process and planning phase. The scheme will involve the crossing of two watercourses, the first being the River Hamble by a new free-span bridge and the second located at Woodhouse Gully / Pudbrook Lake, where an existing culvert will be replaced.
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Freshwater Ecology Surveyor

Aquatic Ecology, Habitat Restoration & Management Plan

Carcinus Ltd was commissioned by a Council as part of an amenity improvement drive to assess the aquatic ecology of a freshwater balance pond and produce a detailed habitat restoration and management plan. The pond was known to be suffering from a number of pre-existing ecological issues including heavy silting, lack of freshwater input and foul odours as well as excessive leaf fall, historic fish kills and infestation by invasive non-native species (INNS).
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Make Contact With Us

Our team are standing by to assist you with your project