Identifying and Mapping Critical American Eel Habitat in the Restigouche and Eel River Estuaries
The overall purpose of this project is to better understand the movement of American Eel within the Restigouche and Eel River estuaries and to identify critical habitat. Presently, there is little understanding of how eels move within these estuaries or how they use specific habitats, such as for feeding, protection, resting, or over-wintering. This project aims to address this gap in the available data.
The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) currently lists American eel as ‘Threatened’. Furthermore, American eel are being considered for listing under the Species at Risk Act, again as ‘Threatened’.
American eel have experienced dramatic declines throughout Eastern Canada mainly related to habitat loss, operation of dams, pollution, and certain fisheries. The Restigouche and Eel River estuaries are both impacted by habitat alteration caused by human activity.
In the Restigouche River estuary, the AV Cell pulp mill effluent pours into the estuary, creating a source of pollution and increasing the water temperature of the surrounding habitat.
In the Eel River system, the habitat is slowly recovering as a result of the removal of the Eel River Bar Dam in 2011. Large sediment deposits that have accumulated over the 40 years of the dam's historic operation still remain in the estuary, and are slowly washing out with tidal waters that were once blocked by the dam.
For both reasons, the project is needed to monitor the critical habitats to help understand and mitigate impacts caused by human interactions.
1) Stable Isotope Analysis
American eel can use a range of different habitats within a river system estuary, which include freshwater (no salinity), brackish water (low to high salinity), and marine water (high salinity) environments. Using stable isotopes analysis on American eel tissue samples, the GMRC will be able to determine what habitat is used for feeding, as the food webs differ between salinity gradients within a estuary, or simply put, the American eel will have different diets in either freshwater, brackish, or marine environments.
On the Restigouche system, the GMRC research team will collect American eel captured in smolt wheel operations. All eels will be sedated using a clove oil solution, and a small fin-clip will be removed from the dorsal area. Eels will be rejuvenated and released. All samples will be processed and shipped according to the protocol identified by the Stable Isotopes In Nature Laboratory (SINLAB) at the Canadian Rivers Institute located in the Biology Department at the University of New Brunswick in Fredericton, NB.
On the Eel River system, American eel will be captured using fyke nets. Traps will be checked daily. Eels will be sedated and sampled the same as the Restigouche system process described above.
For more information on stable isotope research and fish-fin sampling click here.
2) Acoustic Telemetry
During their lifetime in a river system, American eels seasonally migrate between fresh- and salt-water and some eels may remain in one particular environment. Acoustic telemetry methods will involve the surgical implantation of an acoustic tag (9mm diameter by 28 mm length) in eels and installing acoustic receivers at specific locations on the river system to the track movement of the tagged eels within the estuaries. All eels will be sedated prior to surgery.
The collected spatial information, in combination with stable isotopes analysis, will help identify American eel locations and movements within estuaries.
3) Documenting and Mapping Local Mi’gmaq Knowledge
To help understand changes to American eel habitat and American eel ecology (relationships between eel and their natural environment), the GMRC turns to our community harvesters to gather information. Our community members have a special relationship and worldview of the natural world, and their information can help guide research and local resource management. Local observations from both current and past generations can provide invaluable insight into changes to eel behavior and habitat.
Working with community eel harvesters from Eel River Bar and Listuguj, interview and land-use mapping sessions will be used to document local ecological knowledge on American eel within the Eel and Restigouche River estuaries.