Aquatic Biology

UDA offers aquatic habitat characterization and evaluation services. Its scientific and technical qualifications are solicited for conducting environmental impact studies, requesting authorizations (provincial and federal), and performing surveillance and work monitoring in aquatic habitats. UDA’s biologists and wildlife technicians developed their expertise by evaluating biophysical components of over 1,000 watercourses in Québec. The team also possesses substantial experience in developing and monitoring spawning grounds, carrying out water and sediment characterization, and dealing with issues in the fields of population dynamics, benthic ecology and oceanography.


  • aquatic fauna:

     - survey of fish communities with experimental gill nets, fyke nets, seines and portable                electrofishing units;
     - fish identification (including species with a particular status);
     - identification of breeding, rearing and feeding grounds;
     - evaluation of habitat spawning potential;
     - census of spawning grounds;
     - development and monitoring of spawning grounds;
     - fish stocking, telemetry and age determination;
     - characterization of benthic communities;
     - plankton sampling.

  • aquatic habitat:

     - biophysical characterization of rivers, streams, lakes and ponds;
     - substrate characterization;
     - characterization of aquatic and riparian vegetation;
     - identification of natural high water mark;
     - description of flow facies;
     - realization of basic bathymetric profile;
     - measurement of water velocity and flow;
     - physicochemical characterization of water and sediments.

Typical projects : Aquatic Biology


Identification of Natural High Water Mark (NHWM)

For specific projects and various works in aquatic habitats, UDA identified and located the NHWM. This limit is typically identified according to a protocol published by the ministère du Développement durable, de l’Environnement et des Parcs du Québec (now the ministère du Développement durable, de l’Environnement et de la Lutte contre les changements climatiques), namely the expert botanical method or the simplified botanical method.

Fish Surveys

Among the diverse mandates given to UDA, many include fish and fish habitat studies. This was the case of an important environmental impact study related to a pipeline project for which UDA planned and conducted fish community surveys and aquatic habitat characterization for over 800 watercourses. Our survey teams were deployed in several regions of Québec where different kinds of fishing gear were used according to the type of watercourse surveyed. A total of over 40,000 individuals belonging to nearly 70 fish species were captured and identified. Following data analysis, the sensitivity of each watercourse was determined and appropriate methods of work in aquatic habitat as well as specific mitigation measures were identified to alleviate the potential effects on the ecosystem. Comprehensive scientific reports of the study were presented in French and English.

Exclusion of Fish from Seismic Survey Area

In the context of seismic surveys in rivers, UDA developed a protocol aimed at excluding fish from the work area and monitoring potential mortality. Initially, this protocol was presented to authorities in order to obtain the authorizations required to conduct the work. Different techniques were used to perform fish capture and relocation, exclusion from survey area, and continuous monitoring of mortality. In addition, a protocol aimed at assessing the effect of seismic surveys on riverbed with an aquatic camera was designed, if deemed necessary.

Survey of Salmonid Spawning Grounds

During aquatic habitat characterization and fish surveys, salmonid spawning potential was evaluated in watercourses. Following this assessment, a study project was undertaken to survey the number of spawning grounds and to confirm the use of previously documented spawning sites. Watercourses hosting a brook trout or Atlantic salmon population were surveyed using waterscopes and kick nets to identify potential substrates and find eggs. Overall, many habitats initially evaluated as potential spawning grounds were confirmed to be used for reproduction.

Relocation of Shellfish

In the context of construction work involving watercourse crossing, characterizing benthic habitats and organisms can be of great significance. For instance, a characterization of benthic communities was conducted in watercourses subject to be crossed by a pipeline project and known to host a freshwater mussel species with a particular status. Prior to construction work, bivalve shellfish were located, collected, identified and relocated outside the work area. As a mitigation measure for the project, a total of over 1,200 individuals belonging to 10 species of freshwater mussels have been identified and relocated.

Assessment of Water Withdrawal Potential in Lakes

In order to satisfy the specific needs of its clients, UDA has developed customized protocols for characterizing aquatic habitats. This was the case for a project assessing the water withdrawal potential of different lakes. For this purpose, fish surveys and habitat characterization were conducted, a basic bathymetric profile was realized, and the water body renewal capacity was evaluated. The assessment was based on the scenario of a lower water level and its consequences on the availability of spawning, rearing and feeding habitats for the species surveyed.