Abstract1. Population structure, distribution, abundance and dispersal arguably underpin the entire field of animal ecology, with consequences for regional species persistence, and provision of ecosystem services. Divergent migration behaviours among individuals or among populations are an important aspect of the ecology of highly mobile animals, allowing populations to exploit spatially or temporally distributed food and space resources.2. This study investigated the spatial ecology of lake sturgeon (Acipenser fulvescens) within the barrier free Huron-Erie Corridor (HEC), which connects Lake Huron and Lake Erie of the North American Laurentian Great Lakes.3. Over 6 years (2011)(2012)(2013)(2014)(2015)(2016), movements of 268 lake sturgeon in the HEC were continuously monitored across the Great Lakes using acoustic telemetry (10 years battery life acoustic transmitters). Five distinct migration behaviours were identified with hierarchical cluster analysis, based on the phenology and duration of river and lake use.4. Lake sturgeon in the HEC were found to contain a high level of intraspecific divergent migration, including partial migration with the existence of residents. Specific behaviours included year-round river residency and multiple lake-migrant behaviours that involved movements between lakes and rivers. Over 85% of individuals were assigned to migration behaviours as movements were consistently repeated over the study, which suggested migration behaviours were consistent and persistent in lake sturgeon. Differential use of specific rivers or lakes by acoustic-tagged lake sturgeon further subdivided individuals into 14 "contingents" (spatiotemporally segregated subgroups).This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Loss of functional habitat in riverine systems is a global fisheries issue. Few studies, however, describe the decision‐making approach taken to abate loss of fish spawning habitat. Numerous habitat restoration efforts are underway and documentation of successful restoration techniques for spawning habitat of desirable fish species in large rivers connecting the Laurentian Great Lakes are reported here. In 2003, to compensate for the loss of fish spawning habitat in the St. Clair and Detroit Rivers that connect the Great Lakes Huron and Erie, an international partnership of state, federal, and academic scientists began restoring fish spawning habitat in both of these rivers. Using an adaptive management approach, we created 1,100 m2 of productive fish spawning habitat near Belle Isle in the Detroit River in 2004; 3,300 m2 of fish spawning habitat near Fighting Island in the Detroit River in 2008; and 4,000 m2 of fish spawning habitat in the Middle Channel of the St. Clair River in 2012. Here, we describe the adaptive‐feedback management approach that we used to guide our decision making during all phases of spawning habitat restoration, including problem identification, team building, hypothesis development, strategy development, prioritization of physical and biological imperatives, project implementation, habitat construction, monitoring of fish use of the constructed spawning habitats, and communication of research results. Numerous scientific and economic lessons learned from 10 years of planning, building, and assessing fish use of these three fish spawning habitat restoration projects are summarized in this article.

Summary Lake Sturgeon Acipenser fulvescens were studied to determine spawning migrations, seasonal movement patterns and habitat use in the St. Clair River and Lake St. Clair. Ultrasonic transmitters were successfully implanted in 15 sexually mature adult fish during spawning periods in 1997–1999. Telemetry data, along with GIS software, were used to determine where Lake Sturgeon resided in Lake St. Clair following implantation. Movement information collected from tagged Lake Sturgeon from May 1997–October 2000 revealed three patterns. Following implantation, 73% of the fish (four females and seven males) moved downstream from the St. Clair River to Lake St. Clair, 13% of the fish (one female and one male) were presumed to have moved upriver to Lake Huron, and 20% of the fish (one female and two males) remained in or returned to the St. Clair River for at least 1 year. The fish that moved into Lake St. Clair were found most often in an area near the St. Clair River Delta, at depths of 4–6 m (>98% of observations). Fish that remained in the St. Clair River were commonly found (>84%) at depths between 9 and 18 m. Four females and three males returned to the spawning site in the St. Clair River in subsequent spawning seasons. Females returned at intervals of 1–3 years and males at 1–2 years. For all invertebrates tested, only Ephemeroptera density was a significant predictor of Lake Sturgeon presence/absence in Lake St. Clair.

Spawning sites of lake sturgeon Acipenser fulvescens were verified using egg collection mats in the Big Manistee River in northwestern lower Michigan. Photographs taken by a fixed-position underwater video camera were used to characterize the substrate at egg mat locations. A total of 3,913 lake sturgeon eggs were captured at two discrete spawning locations in 2003 and 2004. Spawning locations consisted of 34-44% cobble and 0.04-8% sand, and nonspawning locations consisted of 2-43% cobble and 0.16-7% sand. Shannon diversity indices describing substrate heterogeneity at spawning locations were statistically higher than those for nonspawning locations in 2003 (P ¼ 0.002). Four spawning events (one in 2003 and three in 2004) were documented at water temperatures ranging from 11.18C to 14.88C and egg incubation periods ranging from 6 to 10 d. Depth at spawning sites was 1.5-3.0 m, average water velocity was 0.34-1.32 m/s, and near-substrate water velocity was 0.08-1.26 m/s. The topography of the Big Manistee River channel appears to have been altered by manipulated river flows, resulting in the development of barchans (ridges or shelves along the river bottom) in the region utilized for spawning. This study is the first to document lake sturgeon spawning success in the Big Manistee River and identify the specific characteristics of spawning bed material used as well as the presence of barchans that may produce eddies or turbulent irregular flows that affect egg dispersal and survival.

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