Benchmarks for Great Lakes Fish Habitat Restoration
Description: Great Lakes aquatic habitats and fish communities have changed drastically over the past two centuries due to a combination of persistent and ever-changing anthropogenic stressors. Pollution, hydrological alteration, sedimentation, and overfishing are among the causes of declines in native fishes such as Atlantic salmon and lake trout, while invasive species like alewife and round goby have and continue to alter these ecosystems and affect native fish assemblages (Christie 1974; Sturtevant et al. 2019). Physical habitat restoration is a common approach to rehabilitate fish communities in the Great Lakes region and includes actions such as restoring spawning substrates, reconnecting coastal wetlands and tributaries, and engineering improvements to degraded shorelines and wetlands (Wilcox and Whillans 1999; Manny et al. 2015). Habitat restoration made up a large portion of the Great Lakes Restoration Initiative’s $3.48 billion in funding from 2010–2020, underscoring the importance of careful habitat restoration planning.
Effective habitat restoration relies on careful planning and monitoring which may use reference benchmarks. For restorations with biological objectives, decisions about the type and location of habitat restorations must account for past and future climatic and ecosystem conditions and constraints (e.g., spawning and rearing habitat, prey availability, non-native species) and fish access to restored habitats. Complicating matters, ecological restoration priorities and approaches may differ and conflict among local, state, and federal agencies, and often need to balance tradeoffs with economic and social objectives (e.g., Angradi et al. 2016; Moody et al. 2017). As a result, biological outcomes from these projects are inconsistent (Suding 2011). One way to improve restoration planning and the likelihood of successful outcomes is to develop reference conditions, or “benchmarks,” to serve as comparative ecosystems or assemblages to evaluate restoration “success” (Hawkins et al. 2010). Benchmark development can incorporate current and historical data, expert opinion, and predictive modeling (Hawkins et al. 2010; Suding 2011). Consequently, these approaches may be limited by data availability for different species, life stages, and habitat types (Balaguer et al. 2014). Identifying and addressing these and other limitations to benchmark development and restoration planning will improve future restoration efforts.
Generalized prescriptions for fish habitat restoration across large regions such as the Great Lakes are complicated by several factors, including data availability, spatial representation of habitats, and the applicability of historical data in changing ecosystems. One useful benchmarking approach is to create fish-habitat models using fish occurrence or abundance data in combination with geospatial data. In the Great Lakes region, these approaches have typically been limited to a single lake (e.g., McKenna and Castiglione 2010; Chu et al. 2014), although coarse-scale habitat data frameworks (Wang et al. 2015) permit broader applications of similar models given sufficient biological data (e.g., Kovalenko et al. 2018). Despite this potential, distribution models are often limited by uneven fish data availability and spatial coverage. Landscape-scale monitoring efforts (e.g., Uzarski et al. 2019) can provide data to alleviate these issues and improve habitat-mapping efforts. Additionally, considerable changes to the Great Lakes ecosystem over time (e.g., nutrient inputs, food web structure; Bunnell et al. 2014) require careful evaluation of historical fish data when developing restoration benchmarks.
Coastal and nearshore areas, including shorelines, wetlands, embayments, and tributary outlets, are hotspots of biological productivity and provide essential spawning and rearing habitats for many Great Lakes fish species (Vadeboncoeur et al. 2011; Kovalenko et al. 2019). These habitats are also among the most stressed in the Great Lakes due to their proximity to land-based stressors, such as human development, pollution, dredging, and hydrologic alteration (Goforth and Carman 2005; Allan et al. 2013). Consequently, coastal and nearshore areas are frequent targets for fish habitat restoration in the Great Lakes, with projects seeking to remediate degraded habitats, reestablish fish access to these habitats, and reduce pollutants (Hartig et al. 2020).
Coastal fish habitat restoration efforts in the Great Lakes would benefit from a critical examination of past and current approaches to planning and evaluating (i.e., benchmarking) restoration projects. We seek to bring together a diverse group of scientists with expertise in Great Lakes fish ecology and nearshore ecosystems to discuss approaches, information gaps, and data needs related to fish habitat restoration. To ensure varied perspectives and contributions to the working group, we identified participants from several federal, academic, binational, and non-profit entities and selected individuals to represent diverse expertise and career levels. Collectively, we will summarize the range of approaches used to guide restoration of nearshore fish habitat in the Great Lakes. We will also address the conceptual and data limits of current approaches, such as data availability, quality, and sharing, and underrepresented species and life stages. Lastly, we will outline best practices for establishing benchmarks for future restoration projects under changing ecosystem conditions.
- Synthesize the science guiding past and present fish habitat restoration efforts in the Great Lakes, including the use of spatial and historical benchmarks
- Identify key gaps in knowledge and data that limit current restoration efforts
- Identify best practices for setting Great Lakes fish habitat restoration benchmarks
Ultimately, the goals of this working group will provide guidelines for restoration planning by highlighting ways in which fish habitat restorations have been conducted and to what degree past and present approaches have been “successful.” By bringing together a diverse group of experts to critically examine factors that limit restoration planning and effectiveness, we aim to develop a plan for mitigating these limitations and filling data gaps to improve future fish habitat restoration efforts. Ideally, these discussions and their products will foster a more unified and collaborative approach to coastal restoration projects in the Great Lakes.