The planning component of the Coregonine Restoration Framework is a key step to maximize the probability that the restoration action will be successful. In 2019, fishery managers endorsed a process by which planning teams formed for each of the following planning steps. By 2021, all four teams were active and included 53 individuals spanning 21 entities across Canada and the United States. The first task for each team was to develop methods for each of the four planning steps. Between 2022-2023, the methods were drafted, reviewed by scientists and managers from each lake, and ultimately approved for implementation. Below, a high-level overview of the methods for each planning step is provided.

Image Credit: photographer

Resolve Coregonine Taxonomy

A shortjaw cisco (C. zenithicus, top) and a kiyi (C. kiyi, bottom) from the Thunder Bay region of Lake Superior. Credit: Andrew Muir.

Partitioning animals into units for conservation and restoration starts with a shared language with which to describe diversity. Great Lakes ciscoes display a large amount of morphological variation, and this has made the process of describing taxonomic relationships in the species complex challenging. Are these differences indicative of species? Subspecies? Forms? A large number of environmental and ecological changes have occurred in the Great Lakes since historic taxonomic assignments were established by Koelz in the 1920s, and re-evaluating these relationships in light of 100 years of new knowledge was identified as a primary objective for the planning phase of the CRF.

The Science Team that was assembled to spearhead a review of taxonomy is also developing science-based methods to identify spatial units (that can function at both species or population levels) for resource management across the basin, merging principles of conservation and restoration ecology.

Managers can use identified spatial units to determine where stewardship actions might occur, which could then trigger population viability analyses and threat assessments leading to conservation, restoration, or management planning.

Learn More About Methods Used to Delineate Spatial Units

Archival materials, including books, maps, manuscripts, and photographs, containing valuable historical occurrence data for Great Lakes coregonines. Credit: Cory Brant.

Gap Analysis

In gap analysis, we seek to describe and map historical and contemporary populations and habitats for coregonines.  By taking a deep dive into research archives, museums, and libraries, we can gain a wealth of knowledge related to historical habitats used by coregonines around the Great Lakes.

By comparing this history to what we know today, we can answer questions, like: Have distributions of coregonines shifted? Where did spawning habitats once exist? Where are these habitats now? And, ultimately, which areas might be optimal for managers to target restoration efforts?

These questions are exactly what the Gap Analysis science team in the Coregonine Restoration Framework aim to answer. Already this planning team has identified thousands of historical coregonine spawning and nursery areas by studying several hundred old reports, books, photographs, ship logs, journal entries, and more (see full list here).

Our next step is to use both historical and current coregonine habitat information to model and map where these populations are most likely to spawn today. A lot has changed in the Great Lakes over the past 200 years, and so having a clear understanding of historical conditions, and comparing those conditions to what we have today, is a foundational step for restoring coregonines in the Great Lakes.

A spawning migration of ciscoes (C. artedi) in the Yellowknife River, Great Slave Lake, NT during October. Credit: Paul Vecsei.

Threats Assessment

Threats assessments identify human-driven factors that have caused, are causing, or may cause populations to decline, and they typically combine estimates of a given threat’s impact with its likelihood of occurrence to evaluate risk. The Coregonine Threats Assessment Science Team reviewed many approaches for conducting these assessments and came to consensus to recommend a modified version of the method used by Department of Fisheries and Oceans (Canada) for use within the Coregonine Restoration Framework. Threats assessments conducted using this approach will help to identify key threats and impediments to coregonine restoration, highlight management actions that can alleviate those threats, and provide valuable information for population viability analysis and spatial models.

Buckets of Great Lakes ciscoes ready for freezing, c. 1920s. Credit: USGS Great Lakes Science Center.

Compile data to conduct population viability analysis

Population viability analysis (PVA) uses computer models to predict how a population of fish will change into the future. These models can be very simple and based on observed trends in abundance, or they can be very complex and incorporate all the various components of the fish’s life history (e.g., age, growth, survival, fecundity, etc.) as well as factors that affect each component of the fish’s life history.

This planning step of the Coregonine Restoration Framework gathered the necessary information for the development of PVA models and made recommendations for methods to use given the available information in a particular location for a particular species. Development of PVA models provides a means to evaluate the possible outcome of management actions before they are initiated, thus allowing fisheries managers to make informed decisions that will most likely lead to coregonine restoration.