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Edward F. Roseman

Publications and source records attributed to Edward F. Roseman.

At least 19 recordsLinked to original sources
USGS2025

Detroit River becoming a crucible for boundary organization experimentation

The Detroit River has a long history of human use and abuse, resulting in public outcry over water pollution and resource degradation. This public outcry helped catalyze the enactment of many laws and the Canada-U.S. Great Lakes Water Quality Agreement which led to enhanced research, monitoring, and water pollution control. As pollution from industries and municipal wastewater treatment plants came under control and progress was made in management of single species, the focus shifted to a more comprehensive ecosystem approach that accounted for all the sources of pollution and targeted restoring ecosystem health with resilience. Over time, the Detroit River became a “proving ground” or crucible for experimenting with boundary organizations to overcome geographical, political, institutional, and disciplinary boundaries and strengthen science-policy-management linkages for ecosystem-based management. This study identified 15 boundary organizations functioning in the Detroit River watershed and evaluated two case studies – St. Clair-Detroit River System Initiative and State of the Strait Conferences. Key lessons learned from this study include: 1) establishing boundary organizations, promoting cooperative learning, and building capacity for boundary-spanning are essential for use of an ecosystem approach; 2) boundary spanning requires specific skills, experience, and improved linkages between research and practice; 3) the 15 boundary organizations provide a unique opportunity to collaborate in a community of practice to share knowledge, foster cooperative learning, enhance problem-solving, build trust, and demonstrate leadership; and 4) continued actionable science, investment in capacity building, and cooperative learning are essential to meet long-term goals of sustainability.

Detroit River↗
USGS2025

Visioning and conceptual framework for coordinating Great Lakes connecting waters research and monitoring

The Laurentian Great Lakes are connected via naturally occurring straits and rivers: St. Marys River, Straits of Mackinac, St. Clair-Detroit River System, Niagara River, and the St. Lawrence River. Despite the historical ecological and economic importance of these waters, international agreements (e.g., Great Lakes Water Quality Agreement) only recently explicitly named the Great Lakes Connecting Waters (GLCWs), requiring governments to address the challenges of adequate restoration and protection from historical use and degradation. Standardized research and monitoring activities are needed; however, there is no established mechanism for coordination across the GLCWs. A three-day summit in 2023 convened experts to form the initial framework for a GLCWs Collaborative to increase standardizations and knowledge transfer. Participants drafted a governance structure and priorities following the principles of collective impact but allowed for place-based specificity for local connecting water organizations. Priorities and suggestions for success included: 1) co-development of the collaborative with all rights holders, stakeholders, and surrounding communities; 2) investment in research and technology specific to GLCWs; 3) investment in information transfer and training; 4) increased communication; and 5) better integration into existing Great Lakes research, monitoring, and funding programs. Expanding participation in all local GLCWs organizations with principles of inclusivity was identified as a larger collaborative goal. Next steps in the development of a GLCWs Collaborative include increased communication and formation of working groups and obtaining funding for a dedicated organization to begin supporting activities (communication, facilitation, logistics). By using a deliberate process for establishment, the potentially slower time frame for establishment may result in increased participation and success.

Laurentian Great Lakes↗
USGS2025

Freshwater gastropod (Mollusca: Gastropoda) assemblages, habitat, and the first detection of an invasive gastropod species in two large, dreissenid-influenced, connecting rivers

Native freshwater gastropods are a highly diverse and imperiled group of mollusks in North America and are influenced by a growing number of problematic invasive species. Consequently, there has been an increased need for understanding aquatic gastropod assemblages throughout North America to implement conservation and management strategies. In the Laurentian Great Lakes, gastropod surveys have been sparse, and most surveys have focused on invasive species. To investigate gastropod assemblages in two large connecting rivers of the Great Lakes, the Detroit and St. Clair rivers, benthic surveys were conducted in 2019 and 2021. Sites in the Detroit River (n = 56) and the St. Clair River (n = 51) were surveyed using petite PONAR grabs from which gastropod shells were identified and quantified to family or a group of two combined families. In both the Detroit and St. Clair rivers, the gastropod family Pleuroceridae (37 % and 56 % total composition, respectively) and combined families Amnicolidae + Hydrobiidae (42 % and 23 % total composition, respectively) contributed the most to overall gastropod composition. Invasive Potamopyrgus antipodarum shells were identified at 4 (7 %) Detroit River sites and 10 (20 %) St. Clair River sites and represent the first documented occurrence in the Detroit River. Although this study was limited to quantifying densities based on shells and cannot assume live-collected snail densities, these results provide a baseline knowledge of the gastropod assemblages and habitat use in these two large river systems which can be used to implement conservation and management strategies.

Detroit River, St. Clair River↗
USGS2024

Experimental assessment of egg mat gear retention and collection efficacy

Assessment of egg deposition is widely used to provide an index of spawning efforts for lithophilic spawning fishes. However, little is known about the collection efficacy and bias of fish egg collection methods. We conducted a two-phased study consisting of a simulated-river flume study (two-part design), and a field study (an egg drift comparison with capture on mats) to assess egg collection methods and evaluate egg retention and capture on egg mats. Lake whitefish Coregonus clupeaformis egg retention on seeded mats decreased with increasing velocity and walleye Sander vitreus egg retention was variable as velocity increased. Fewer lake whitefish eggs were collected on egg mats when limestone reef rock was present in the flume study during the simulated spawned trials, but the inverse was true for walleye. Similarly, during field collections more lake whitefish eggs were collected in benthic D-shaped frame (D-frame) drift nets set near a known spawning reef compared to egg mats set on the reef, indicating lake whitefish eggs were drifting downstream along the river bottom. In contrast, fewer walleye eggs were observed in D-frame drift nets compared to number of eggs captured on the egg mats. Therefore, egg mats are an informative tool for evaluating walleye egg deposition in an immediate area but may underestimate egg deposition of lake whitefish, especially in lotic systems. Compared to other egg collection methods in the current literature, our study indicates that egg mats are useful for assessing egg deposition by lithophilic spawning fishes, but that the collection and retention efficacy and bias of this gear may vary between species and habitat types.

Journal of Fish and Wildlife Management↗
USGS2024

Genetic origins of a resurging lake whitefish, Coregonus clupeaformis, population in the Detroit River, Laurentian Great Lakes

The Detroit River connects Lake Huron and Lake Erie of the Laurentian Great Lakes. The river once supported a substantial lake whitefish ( Coregonus clupeaformis ) fishery until the early 1900s, when habitat loss, pollution, and overfishing contributed to the collapse of the fishery and loss of spawning populations in the river. In the early 1970s, efforts were initiated to improve water and habitat quality, and in December 2005 a spawning male lake whitefish and viable eggs were collected; the first documented evidence of spawning since 1916. Researchers have tracked the spawning magnitude of the lake whitefish population in the Detroit River since 2005 by assessing the number of eggs deposited on egg mats. Genetic analysis of larval fish hatched from eggs collected in the field between 2005 and 2018 was used to determine the relative contributions of Lake Erie and Lake Huron to the resurging population. Over 80% of the hatched larvae had parents originating from Lake Erie in all the years sampled. The estimated number of full-sibling families sampled at Belle Isle was the same in 2010 and 2014 and varied between 2009 and 2016 at Fighting Island. The estimated number of lake whitefish parents at Fighting Island decreased in the most recent collections possibly due to loss of habitat on spawning reefs due to sedimentation. Our results provide additional evidence that restored spawning habitat in the Detroit River is again being used by lake whitefish and continued reproduction at these sites may improve the Great Lakes portfolio of ecological and genetic diversity.

Detroit River↗
USGS2024

How well do existing surveys track fish community performance measures in the St. Clair-Detroit River System?

The St. Clair-Detroit River System (SCDRS) connects Lake Huron to Lake Erie and provides important habitats for many fishes of economic and ecological importance. Portions of the SCDRS are designated as Great Lakes Areas of Concern and fish production and conservation may be compromised. Efforts to address beneficial use impairments have focused on restoring habitat for native fishes and improving aquatic ecosystem health. Considerable site-specific research and long-term, annual fish surveys have examined responses to habitat improvements. However, there is uncertainty surrounding whether individual studies and surveys can assess (1) population-level benefits of habitat enhancements and (2) whether management objectives are being met. To identify monitoring gaps and inform long-term monitoring program development, we compared outputs from SCDRS fish monitoring surveys (based on discussions with regional agencies) with performance measures specified in management plans (obtained through gray literature searches). Performance measures for harvested species aligned well with outputs of existing surveys. In contrast, at-risk fishes often had objectives and performance measures that reflected knowledge gaps and study needs. Although harvested species were well-monitored relative to specified performance measures, at-risk fishes were less reliably collected by existing surveys, except for lake sturgeon Acipenser fulvescens . Effective evaluation of restoration efforts for at-risk fishes may require additional survey efforts that target species-specific habitat use and life history characteristics.

Michigan↗
USGS2024

Larval Lake Whitefish (Coregonus clupeaformis) zooplankton consumption remains constant despite variation in prey densities in western Lake Erie

Larval fish growth and survival could be limited or reduced due to patchiness of zooplankton densities, even in productive aquatic systems. Recent declines in Lake Whitefish ( Coregonus clupeaformis ) populations prompted research to identify underlying mechanisms controlling survival at early life stages. In Lake Erie, the bottleneck window controlling year-class strength of Lake Whitefish likely occurs during the first growing season, suggesting that availability of important prey could influence year-class strength. Therefore, spatial and temporal larval Lake Whitefish distribution, diet, and prey utilization were evaluated in western Lake Erie. The pelagic Lake Whitefish larval period in the western basin extends from April 1 to May 15 with most larvae concentrated nearshore at the surface both day and night. Cyclopoid copepods were the most important prey item; however, calanoid copepods and Cladocera were consistently consumed, indicating that copepods and Cladocera were important larval Lake Whitefish prey items. Copepod and Cladocera biomass were the highest nearshore, overlapping with the highest larval Lake Whitefish densities. However, the amount of food consumed by larvae was consistent in all areas, suggesting that offshore areas in western Lake Erie with relatively low zooplankton biomass harbor enough food to satiate larval Lake Whitefish. Therefore, it is unlikely that prey availability limits survival through means of starvation during the larval phase.

western Lake Erie↗
USGS2024

Broad scale community-level larval fish survey of southern Lake Erie

The early-life history stages of fish are sensitive to environmental change and therefore can indicate habitat quality as well as help predict recruitment of resident and transient fishes. In 2019, as part of the Lake Erie Cooperative Science and Monitoring Initiative, we conducted a lake-wide assessment of the ichthyoplankton community in U.S. nearshore waters and international offshore waters. The goal of this work was to characterize the larval fish community across the lake and assess species composition, phenology, and distribution of larvae. Ichthyoplankton were sampled weekly using bongo nets at ports beginning at the Detroit River and along the southern shore of Lake Erie to Dunkirk, NY, and less frequently in the Niagara River and offshore areas. Larval fish were present from March 26 through August 29, 2019. The first taxon to emerge was Lake Whitefish in all basins, followed by Walleye, Yellow Perch, and catostomids, depending on port. Mean total density peaked in mid-June due to high catches of Gizzard Shad, Morone spp., and Freshwater Drum in the western basin. Few fish were collected in the offshore sites. Taxa richness, diversity, and larval density were higher in the western basin and lower in the central and eastern basins, generally following the productivity gradient. This was the first study to provide a comprehensive community assessment of the ichthyoplankton community of Lake Erie and can provide a baseline to assess future change, especially in community composition or phenology, of larvae which are likely to respond to climate and habitat change.

Lake Erie↗
USGS2024

Status and trends of the Lake Huron prey fish community, 1976-2023

The U. S. Geological Survey-Great Lakes Science Center has monitored annual changes in the offshore (depth >9m) prey fish community of Lake Huron since 1973. Monitoring of prey fish populations in Lake Huron is based on a bottom trawl survey that targets demersal (benthic) species and an acoustic-midwater trawl survey that targets pelagic species and life stages. In 2023, Bloater ( Coregonus hoyi ) accounted for 77% of the main basin biomass in bottom trawls and 86% of the main basin biomass in the acoustics survey. Despite this sustained importance of native species in the main basin, species diversity is below desired levels. Bloater in the main basin has exhibited population growth and strong recruitment in recent years, and Cisco ( Coregonus artedi ) has exhibited increased biomass in the North Channel since 2015. In contrast non-native Alewife ( Alosa pseudoharengus ), whose population collapsed in 2004 and has not recovered, were less than 1% of fish biomass in 2023. Rainbow Smelt ( Osmerus mordax ) accounted for 7% of the main basin biomass in bottom trawls and 22% of the main basin biomass in the acoustics survey. Despite remaining the second-most abundant prey species in the main basin, Rainbow Smelt has not shown appreciable increases in biomass despite recent strong year classes. Deepwater Sculpin ( Myoxocephalus thompsonii ) increased by 47% in 2023 and were 33% of the long-term average. Slimy Sculpin ( Cottus cognatus ) increased to 60% of the long-term average but remained rare in bottom trawl catches. In contrast, biomass of Round Goby ( Neogobius melanostomus ), a non-native species similar ecologically to the sculpin species, remained near the record high biomass reached in 2022. Current lake conditions characterized by ongoing oligotrophication seem to favor native coregonines over non-native fishes. Use of complementary surveys (bottom trawl, acoustics) remains important for evaluating prey fish status in Lake Huron, where prey fish community dynamics vary by basin and prey fish responses to changing environmental conditions depend on species and/or habitat.

Lake Huron↗
USGS2023

Food web changes reflected in age-0 piscivore diets and growth

Lake Erie walleye ( Stizostedion vitreum ) recruitment fluctuates annually and depends partially on their diet and growth during their first year of life. In recent decades, age-0 walleye diet and growth may be responding to food web changes in western Lake Erie. To determine how age-0 walleye have responded to changes in prey species and abundance, we compared diet between 2019, 2014 and 1994–1999. Larval walleye ate predominantly cyclopoids in 2019, compared to 1994–1999 when calanoids were the most consumed copepod. Juvenile walleye ate predominantly large cladocerans and benthic invertebrates in 2019, compared to 2014 and 1994 when fish was the most consumed prey. Additionally, in 2019 and 2014, age-0 walleye ate two of the current aquatic invasive species (AIS), Bythotrephes longimanu s and Neogobius melanostomus , and the historical AIS, Osmerus mordax . Age-0 walleye were smaller in 2019 than in 2014 and switched to consuming more AIS and less fish suggesting that more energetically favourable prey were not available. While age-0 walleye showed adaptation to new prey and conditions, they had a lower quality diet because they consumed less fish, but also because the invasive fish they now consume have a lower energy density than native species. However, lower quality diet and size may not result in reduced survival, if adequate alternative prey is available. Continued monitoring of age-0 walleye diet could provide confirmation that lower diet quality during the first year decreased walleye growth and aid to identify any effects changes in age-0 diets has on recruitment to the adult population.

Michigan, Ohio↗
USGS2023

Lake sturgeon population trends in the St. Clair–Detroit River System, 2001–2019

Lake Sturgeon Acipenser fulvescens are listed as threatened or endangered in 15 states or provinces within their native range. Accordingly, investments in habitat and population restoration for this species have increased throughout the Great Lakes. To aide evaluation of restoration efficacy, robust population parameters are needed to inform management decisions. The St. Clair – Detroit River System (SCDRS) contains one of the largest self-sustaining Lake Sturgeon populations in the Great Lakes; however recent estimates of population abundance and growth parameters have not been assessed. Our study used baited setline and mark-recapture data collected between 2001 – 2019 to estimate whether the number of Lake Sturgeon captured varied annually and/or with water temperature and whether population abundance and population growth rate varied among three sub-populations located in the SCDRS. Trends in the number of Lake Sturgeon captured on setlines varied among sub-populations and by life stage. Annual trends in the number of Lake Sturgeon captured remained consistent over time in the upper St. Clair River, decreased for adults and increased for subadults in the lower St. Clair River, and increased in the Detroit River. With sub-population abundance of 20,184 (95% CI = 12,533 – 27,816) in the upper St. Clair River/southern Lake Huron, 6,523 (95% CI = 5,720 – 7,327) in the lower St. Clair River, and 6,416 (95% CI = 4,065 – 8,767) in the Detroit River, our study confirms that the SCDRS contains the largest Lake Sturgeon population with unimpeded access to the Great Lakes. The geometric mean population growth rate ( λ ) for all sub-populations indicated stable populations and ranged from 1.00 – 1.16. Our study provides an updated assessment of Lake Sturgeon population parameters that serve as a baseline to evaluate habitat restoration efforts and inform management of the SCDRS recreational Lake Sturgeon fishery.

Michigan, Ontario↗
USGS2023

Status and trends of the Lake Huron prey fish community, 1976-2021

The U.S. Geological Survey Great Lakes Science Center has assessed annual changes in the offshore prey fish community of Lake Huron since 1973. Assessments are based on a bottom trawl survey conducted in October of each year and an acoustics-midwater trawl survey, which began in 2004 and is conducted in September-October. Due to weather delays and continued travel restrictions during 2021, there were no bottom trawl samples off the port of Goderich, Ontario and two acoustic transects were cancelled in Georgian Bay. Prey fish biomass in Lake Huron in 2021 was dominated by two species, Bloater (Coregonus hoyi) and Rainbow Smelt (Osmerus mordax). In the main basin, prey fish biomass remained below levels observed prior to community-wide declines that began in the early to mid 1990s. Bloater was the most abundant prey fish species in the main basin, whereas Rainbow Smelt was the most abundant prey species in the North Channel and in Georgian Bay. Both surveys suggested that Bloater biomass is increasing in the main basin. Low biomass of invasive species like Alewife (Alosa pseudoharengus) and Rainbow Smelt is consistent with fish community objectives focused on restoration of native fish communities. Abundance of invasive Round Goby (Neogobius melanostomus) increased in 2021 relative to 2019-2020. Biomass of the native Cisco (Coregonus artedi) increased in the North Channel in 2021 but remained low in Georgian Bay, possibly as an artifact of reduced sampling. Biomass of Slimy Sculpin (Cottus cognatus) and Deepwater Sculpin (Myoxocephalus thompsoni) in 2021 remained low but within the range observed over the past decade. Reduced lake productivity, predation by a recovering piscivore community, and shifts in food web dynamics that favor fish production in nearshore environments may prevent prey fish biomass in offshore areas from returning to levels observed prior to the early 1990s. However, increased biomass of Bloater and Cisco suggests that lake conditions may favor recovery of native corgonines.

Lake Huron↗
USGS2023

Status and trends of the Lake Huron prey fish community, 1976-2022

The United States Geological Survey-Great Lakes Science Center has monitored annual changes in the offshore prey fish community of Lake Huron since 1973. Monitoring of prey fish populations in Lake Huron is based on a bottom trawl survey that targets demersal (benthic) species and an acoustic-midwater trawl survey that targets pelagic species and life stages. Status of the main basin prey fish community in 2022 was considered ‘Fair’ due to sustained improvements in native species status but species diversity that remains below desired levels. Current lake conditions, characterized by ongoing oligotrophication, seem to favor native coregonines like Bloater ( Coregonus artedi ), which in the main basin has exhibited signs of population growth and strong recruitment in recent years, and Cisco ( Coregonus artedi ), whose biomass in the North Channel increased for the second consecutive year in 2022. In contrast, conditions in the main basin are less favorable for exotic prey fish such as Alewife ( Alosa pseudoharengus ), whose population collapsed in 2014 and has not recovered, and Rainbow Smelt ( Osmerus mordax ), which remains the second-most abundant prey species in the main basin but has produced multiple weak year classes over the past decade including in 2022. Status of benthic prey fish in the main basin in 2022 depended on species. As in prior years, the native sculpin community in 2022 consisted primarily of Deepwater Sculpin ( Myoxocephalus thompsoni ) because Slimy Sculpin ( Cottus cognatus ) has become exceedingly rare. In contrast, biomass of the ecologically similar Round Goby ( Neogobius melanostomus ), an exotic species, reached an all-time high in 2022. Use of complementary surveys (bottom trawl, acoustics) remains important for evaluating prey fish status in Lake Huron, where prey fish community dynamics vary by basin and prey fish responses to changing environmental conditions depend on species and/or habitat.

Lake Huron↗
USGS2022

Identifying and characterizing juvenile lake sturgeon (Acipenser fulvescens, Rafinesque, 1817) occupancy hot spots within the St. Clair-Detroit River System

Over the past two decades, extensive monitoring has been conducted in the St. Clair – Detroit River System to describe spatial and temporal patterns of lake sturgeon ( Acipenser fulvescens ). To characterize spatial patterns in juvenile lake sturgeon (<1000 mm TL) based on survey collections, ‘hot spots’ were identified through optimized hot spot analysis (HSA). This HSA was then interpolated by inverse distance weighted analysis to determine extent of identified ‘hot spots’ and ‘cold spots’. Additionally, habitat variables (i.e., water depth, water velocity, and dominant substrate type) were investigated using a single season occupancy model to determine their influence on juvenile lake sturgeon occupancy probability. In total, 1203 juvenile lake sturgeon were captured across 4197 surveys. Three unique ‘hot spots’ were identified; western Lake Erie, Fighting Island in the Detroit River, and the North Channel in the St. Clair River. Interpolated ‘hot spots’ encompassed 73.1 km² in western Lake Erie, 4.7 km² near Fighting Island, and 6.6 km² in the North Channel. Detection probabilities within ‘hot spots’ ranged from 8.8%–43.4%. No habitat variables significantly predicted juvenile lake sturgeon occupancy. Juvenile lake sturgeon were captured in western Lake Erie where the water depth was >5.1 m and odds of occupancy increased with increased water velocity. Juvenile lake sturgeon in the Detroit and St. Clair River ‘hot spots’ were captured at sites with mean benthic water velocities ranging from 0.20–0.60 m/s and where water depth was >7.3 m. Irrespective of waterbody, 69% of all juveniles were detected over dominant sand and gravel substrates. These results provide valuable insight about juvenile habitat use that can help managers formulate effective conservation and restoration strategies supporting the continued recovery of Great Lakes lake sturgeon.

Michigan↗
USGS2022

Contemporary spatial extent and environmental drivers of larval coregonine distributions across Lake Ontario

Coregonine fishes are important to Laurentian Great Lakes food webs and fisheries and are central to basin-wide conservation initiatives. In Lake Ontario, binational management objectives include conserving and restoring spawning stocks of cisco ( Coregonus artedi ) and lake whitefish ( C. clupeaformis ), but the spatial extent of contemporary coregonine spawning habitat and the environmental factors regulating early life success are not well characterized. In Spring 2018, we conducted a binational ichthyoplankton assessment to describe the spatial extent of coregonine spawning habitat across Lake Ontario. We then quantified the relative importance of a suite of biophysical variables hypothesized to influence coregonine early life success using generalized additive mixed models and multimodel inference. Between April 10 and May 14, we conducted 1,092 ichthyoplankton tows and captured 2,350+ coregonine larvae across 17 sampling areas, predominantly within embayments. Although 95% of catches were in the eastern basin, coregonine larvae were also found in historical south shore spawning areas. Most coregonine larvae were cisco; <6% were lake whitefish. Observed catches of both species across sampling areas were strongly and similarly associated with ice cover duration, but the importance of site-specific characteristics varied, such as distance to shore and site depth for cisco and lake whitefish, respectively. These results suggest that regional-scale climatic drivers and local environmental habitat characteristics interact to regulate early life stage success. Furthermore, strong regional and cross-species variation in larval distributions emphasize the importance of lake-wide assessments for monitoring both the current eastern basin populations and potential expansions into western Lake Ontario habitats.

Lake Ontario↗
USGS2022

An evaluation of fish spawning on degraded and remnant reefs in Saginaw Bay, Lake Huron

Saginaw Bay is a shallow, nutrient-rich embayment in Lake Huron that historically had a complex network of natural rocky reefs. These reef habitats were used as spawning and nursery areas for a variety of fish species, but decades of land-use related sedimentation caused many of these reefs to be degraded. Our study objectives were to analyze abiotic and biotic conditions on degraded and remnant reefs and describe spawning patterns of walleye ( Sander vitreus ) and lake whitefish ( Coregonus clupeaformis ) at these sites to determine the potential for increased utilization following reef restoration. During fall and spring 2014–2016, we evaluated water quality and egg predation at four sites with varying levels of reef degradation. Further, we documented reproductive utilization through capture of spawning adults and quantification of egg deposition. Walleye and lake whitefish utilized multiple sites for reproduction; however, densities of spawners and deposited eggs were low, suggesting that they were not utilizing study sites as major spawning locations. Walleye and lake whitefish eggs were eaten by multiple fish species, including larger fish such as channel catfish ( Ictalurus punctatus ). Dissolved oxygen levels were adequate (i.e., >7 mg 0 2 L −1 ) during spring walleye egg incubation; however, bottom dissolved oxygen levels became very low at some sites during winter ice cover, coinciding with lake whitefish egg incubation. As restoration of rocky reefs proceeds in the Bay, evidence of remnant reef spawning fish bodes well for long-term success, though potential limiting factors such as low dissolved oxygen, sedimentation, and egg predation require continued monitoring.

Michigan↗
USGS2022

Predicting physical and geomorphic habitat associated with historical lake whitefish and cisco spawning locations in Lakes Erie and Ontario

The Great Lakes basin was historically populated by multiple, coevolved coregonine species, but much of that diversity has been lost. In Lakes Erie and Ontario, both lake whitefish ( Coregonus clupeaformis ) and cisco ( Coregonus artedi ) occurred in high numbers before habitat degradation, overfishing, invasive species, and other factors caused significant declines. There is growing interest in restoring these populations, and suggested actions include restoration of critical habitats such as spawning habitat. Unfortunately, our current understanding of lake whitefish and cisco spawning habitat characteristics and locations in these lakes is limited. To highlight areas of potential importance for conservation and restoration, we used random forest models and data on historical spawning locations to predict lake whitefish and cisco spawning habitats based on hypothesized key factors including wind fetch, ice cover duration, distance from 1st and 6th order tributaries, and lake bottom substrate. Our model accurately predicted spawning habitat locations for 71% and 54% of cases for lake whitefish and cisco, respectively. Fetch was the most important variable in the lake whitefish model, with spawning habitats being most likely to occur in regions of low to moderate fetch. Cisco spawning habitats were most likely to occur in areas of relatively low fetch near a 1st order stream. We used these models to predict spawning habitat locations for both species across Lakes Erie, Ontario, and St. Clair. Our results improve our understanding of lake whitefish and cisco spawning habitat characteristics and will aid in the spatial prioritization of actions to restore these native fishes.

Lake Erie, Lake Ontario↗