Assessing threats to fish and fish habitat through science and monitoring

Our knowledge about the health of species and habitat is only as good as the data we collect and share with others. Scientific research, monitoring, and data collection help us understand how threats like habitat modification from development activities are impacting fish and fish habitat. This informs the decisions we make about the best ways to protect fish and their habitat.

Science to support evidence-based decision-making

Our Fish and Fish Habitat Protection Program (FFHPP) works closely with departmental scientists to ensure that decision-making processes and tools are informed by current, peer reviewed science. These processes and tools guide the review of project proposals using a risk-based approach. For example:

• Pathways of effects diagrams are used to show the linkages between a particular work, undertaking or activity and the pressures they can impose on aquatic ecosystems. These diagrams help to identify potential risks to fish and fish habitat and the measures that can be used to minimize those risks.
• The habitat ecosystem assessment tool is used to assess losses, gains and modifications to habitat that result from development, offsetting, and restoration activities. It is also used to predict the response of fish populations to development activities and mitigation options. Fisheries and Oceans Canada (DFO) currently uses the tool in the Great Lakes basin.
• The Canadian Science Advisory Secretariat performs regional and national peer reviews to inform our decision-making.

Research on aquatic invasive species (AIS) tends to focus on providing advice for early detection and surveillance, potential ecosystem impacts, and management measures for new and existing AIS. For example, DFO’s research into the life cycle of sea lamprey led to the development of selective lampricides aimed at killing young lamprey. These lampricides have been successful in reducing sea lamprey populations in the Great Lakes helping to protect Great Lakes salmonoid stocks. Sea lamprey is an invasive species that has threatened the Great Lakes for decades. Their aggressive feeding behaviour imposes biological stress on the native fish populations.

DFO also monitors aquatic species at risk in fresh water to determine the relative risk of threats and impacts to the recovery of these species. A noteworthy accomplishment was the conclusion, in 2021-22, of the three-year Canadian Freshwater Species at Risk Research Network with a seminal special issue of the Canadian Journal of Fisheries and Aquatic Sciences titled Science to support Canada’s SARA-listed freshwater species, which addresses critical threat and reintroduction research gaps for a multitude of Canadian freshwater fishes and mussel species listed under the Species at Risk Act (SARA).

DFO also examined the impacts that climate change can have on aquatic ecosystems and infrastructure through risk-based assessment reports for each of four large aquatic basins (Arctic, Pacific, and Atlantic basins and the freshwater basin comprising the Lake Winnipeg watershed and the Great Lakes St. Lawrence drainage). The results were used to help departmental decision-makers know where to focus adaption strategies, and to inform the design of the Aquatic Climate Change Adaptation Service Program. Science and research at DFO have been instrumental in contributing to Canada’s Changing Climate Report, and to other public reports about the state of Canada’s ocean ecosystems (i.e. State of Canada’s Oceans).

Compliance and effectiveness monitoring

For projects taking place in or near water that may impact fish and fish habitat, the FFHPP monitoring program verifies the implementation of management measures that are recommended (through letters of advice to proponents), or imposed as conditions of authorization or permits issued by the department. This is done both through site visits and review of reports required to be provided to the department by project proponents. This monitoring information, in addition to advice provided by DFO scientists, assists us in determining the effectiveness of avoidance, mitigation and offsetting measures, and contributes to continually improving the management of risks to fish and fish habitat.

Freshwater monitoring

Environment and Climate Change Canada (ECCC), in collaboration with provincial and territorial governments (and in some cases with the assistance of Indigenous Peoples, institutions, or volunteers), monitors fresh water in Canada through various networks:

• The National Hydrometric Monitoring Network provides information on water levels and flows at over 1900 hydrometric monitoring stations across Canada.
• The Long-Term Freshwater Quality Monitoring Network provides water quality (temperature, pH, alkalinity, major ions, nutrients, and metals) information from over 171 federal, federal-provincial and federal-territorial sampling sites across Canada. The data from this network informs the Canadian Environmental Sustainability Index water quality indicator, which provides a measure of the ability of river water across Canada to support plants and animals.
• Data collected through the Canadian Aquatic Biomonitoring Network helps us assess the health of a water body based on the count and composition of benthic macroinvertebrates - organisms like worms, crustaceans, molluscs and the larval stages of many insects that that live in / on sediments at the bottom of rivers, streams, and lakes. This biomonitoring can give insight into the presence of exotic species, changes over time caused by habitat degradation and climate change, changing water levels and flows, the presence of unknown contaminants, and the effects of chemical interactions.

Environmental indicators

Canadians care about their natural environment. They want to know that habitat is healthy and that current approaches to protecting fish and fish habitat are effective.

Environmental indicators can be used to communicate the current health of a particular species or habitat based on one or more measurable characteristics. A simple indicator, like extent of Canada’s wetlands (the percentage of an ecozone that is classified as a wetlands), when tracked over time, can provide a snapshot of aquatic ecosystem health, where decreasing wetland extent over time corresponds to reduced ecosystem health.

Canada’s conserved areas indicator shows the value that indicators have in measuring progress towards goals or targets. Canada is currently aiming to conserve 25% of our lands and 25% of our oceans by 2025, and 30% of each by 2030, under Canada’s National Biodiversity Strategy and Action Plan.

More complex indicators, like the Canadian Environmental Sustainability Index water quality indicator (calculated based on several different physical-chemical parameters), can be used for summarizing large data sets and conveying results in simple terms, and for comparing results between different sites and / or periods of time.

In many of the Habitat Highlights, general indicators of species or habitat health are represented using a metric (a measurable attribute) based on data availability. In the Habitat Highlight: Assessing aquatic connectivity in Nova Scotia, we see how available data is used to calculate two different metrics that describe aquatic connectivity: the amount of habitat that is inaccessible to fish due to dams, and the density of watercourse crossings

Values of an indicator or metric can be grouped into categories based on thresholds, to communicate results in a clear and consistent manner. A threshold can be a scientifically derived value or be based on an assessment of risk but should identify a point at which there is an expected change in state or health.

Choosing the right indicators

Choosing appropriate indicators depends on many factors including the subject matter, and how the indicators will be used. The international Organisation for Economic Co-operation and Development (OECD), for example, publishes a wide range of environmental indicators in support of their mandate of “establishing evidence-based international standards and finding solutions to a range of social, economic and environmental challenges.” OECD indicators must be broad enough to be applicable across many different member countries, and reflect the mandate of the OECD. These indicators are necessarily different than the indicators that might be used by a small community group monitoring the health of their local watershed.

Nevertheless, the criteria for selecting quality indicators are consistent across many organizations and domains. The Fraser Basin Council, a not-for-profit organization dedicated to advancing sustainability in the Fraser Basin and across British Columbia, lists the following criteria when choosing indicators of sustainability (both environmental and socio-economic) for the Fraser Basin watershed^{Footnote 1}:

• available: data are available and easily accessible
• understandable: data are easily understood by a diverse range of non-technical audiences
• credible: data are supported by valid, reliable information and interpreted in a scientifically defensible manner
• temporal: data have the capacity to measure trends over time
• relevant: data/indicator reflects community values and interests
• integrative: data demonstrates connections among key dimensions of sustainability
• comparable: data can be compared across regions

There is no one size fits all approach for reporting on the health of a watershed and using environmental indicators. The approach(es) will reflect the unique circumstances of the region, the data available to undertake an analysis, and the objectives and priorities of the people that live there.

Noteworthy environmental indicator projects

In Canada, several agencies and groups develop and report on environmental indicators related to fish and fish habitat as part of their watershed specific assessment initiatives.

In their watershed reports^{Footnote 2}, the World Wildlife Fund (WWF) Canada have developed an assessment framework and used it to examine indicators of health (hydrology, water quality, benthic invertebrates, and fish) and threats (pollution, habitat loss, habitat fragmentation, overuse of water, invasive species, climate change and alteration of flows) in each of Canada’s 164 sub-watersheds.

Under the Great Lakes Water Quality Agreement, Canada, the United States, and many partners, assess the state of each of the Great Lakes using 9 high-level indicators of ecosystem health (drinking water, beaches, fish consumption, toxic chemicals status, habitat and species status, nutrients and algae status, invasive species prevention, groundwater status, and watershed impacts and climate trends). The 2022 State of the Great Lakes report shows while that progress is being made on many fronts, threats such as nutrients and invasive species are prevalent in some areas, and climate change is increasing the impacts of some threats.

The Canadian Environmental Sustainability Indicators program provides data and information to track Canada’s performance on key environmental sustainability issues, including climate change, air quality, water quality and availability, and protecting nature. The indicators are prepared by Environment and Climate Change Canada with the support of other federal government departments, as well as provincial and territorial governments.

Human Activity and the Environment 2021: Accounting for ecosystem change in Canada provides some of the latest statistics on the extent and condition of Canada’s ecosystems, as well as estimates of the supply and use of selected ecosystem services.

We also recently completed a Canadian Science Advisory Secretariat process to examine potential indicators, metrics, and corresponding thresholds to reflect the health of habitat in the Lower Great Lakes and the Eastern Slopes of Alberta.