Use of main channel and two backwater habitats by larval fishes in the Detroit River Erik A. McDonald a,1 , A. Scott McNaught a, ⁎, Edward F. Roseman b a Central Michigan University, 217 Brooks Hall, Mount Pleasant, MI 48859, USA b USGS Great Lakes Science Center, 1451 Green Road, Ann Arbor, MI 49105, USA abstract article info Article history: Received 3 April 2012 Accepted 19 September 2013 Available online 26 October 2013 Communicated by Nicholas Mandrak Index words: Larval fishes Habitat use Diet Growth Nursery area Detroit River Recent investigations in the Detroit River have revealed renewed spawning activity by several important fishes, but little is known about their early life history requirements. We surveyed two main channel and two backwater areas in the lower Detroit River weekly from May to July 2007 to assess habitat use by larval fishes. Backwater areas included a soft-sediment embayment (FI) and a hard-sediment area (HIW). Main channel sites were located adjacent to each backwater area. Water temperature, velocity and clarity measurements and zooplankton samples were collected weekly. A macrophyte assessment was conducted in July. Growth and diet of larval yellow perch (Perca flavescens), bluegill (Lepomis macrochirus) and round goby (Neogobius melanostomus) were used to assess habitat quality. Macrophyte diversity and percent cover were higher and velocity lower at FI than HIW. Although larval fish diversity was highest in the main channel, yellow perch and bluegill larvae only grew beyond the yolk stage at FI, where they preferentially selected copepods, while Daphnia were selected in the main channel. Round goby ate harpacticoid copepods and Daphnia and grew at similar rates in HIW and the main channel. These data indicate that FI was a valuable nursery area for yellow perch and bluegill, whereas HIW was better suited to round goby. We only assessed two backwater areas, thus a complete census of wetland areas in the Detroit River is needed to identify valuable habitats. Restoration of shallow backwater areas is essential for rehabilitating fish populations and should be a priority in the Detroit River. © 2013 International Association for Great Lakes Research. Published by Elsevier B.V. All rights reserved. Introduction The Detroit River is part of the Huron–Erie Corridor (HEC) connecting Lake Huron to Lake Erie and serves as an important migration route for many fishes, some of whom use it for spawning and early life stage development. At least 21 species of larval fishes have been documented in the Detroit River; the most abundant included rainbow smelt, alewife and gizzard shad (Hatcher and Nester, 1983). Important sport and commercial fishes that use the river for spawning, nursery, and adult habitat include crappies, lake sturgeon, lake whitefish, largemouth bass, smallmouth bass, and walleye, (Caswell et al., 2004; Goodyear et al., 1982; Hatcher and Nester, 1983; Roseman et al., 2011). Habitat loss is a major factor affecting fishes in the Detroit River. Most of the historic coastal wetlands on the Michigan side have been lost (Manny, 2003). Pollution from bordering industrial facilities, waste discharge from nearby cities, armored shorelines, dredging, and channel construction have also contributed to the reduction of habitat in the Detroit River (Manny, 2003; Manny et al., 1988). Human activities such as recreation, power generation, and transportation also negatively affect the suitability of the river for fishes (Manny, 2003). Research that quantifies the abundance and functionality of remaining spawning and nursery habitats is needed to provide resource managers with contemporary scientific information necessary to develop strategies that protect and restore the health and productivity of the river. Contemporary lotic habitats in the Detroit River are diverse and include natural river channels such as the lower Trenton Channel where the river bottom has not been dredged, deep channels that accommodate large ships such as the dredged Amherstburg Channel, and constructed channels that are long, deep, and narrow such as the Livingstone Channel (Derecki, 1984; Edwards et al., 1989). The few remaining littoral habitats are equally diverse in structure and size and include diked wetland complexes, littoral fringes along main channel areas, marinas, and backwater embayments and invaginations (Derecki, 1984; Manny et al., 1988). The diversity of habitat types offers the potential for the Detroit River to meet the life history requirements for numerous native fishes underscoring the ecological importance of this system. Recent investigations of fish habitat use in the Detroit River have revealed renewed spawning activity by several socially and ecologically important fishes including lake whitefish (Roseman et al., 2007, 2012), walleye (Manny et al., 2007) and lake sturgeon (Caswell et al., 2004; Roseman et al., 2011). In addition, some nearshore areas of the Detroit Journal of Great Lakes Research Supplement 40 (2014) 69–80 ⁎ Corresponding author. Tel.: +1 989 774 1335. E-mail addresses: emcdonal@u.washington.edu (E.A. McDonald), mcnau1as@cmich.edu (A.S. McNaught). 1 Present address: University of Washington, Tacoma, 1900 Commerce St., Tacoma, WA 98402 USA. 0380-1330/$ – see front matter © 2013 International Association for Great Lakes Research. Published by Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.jglr.2013.10.001 Contents lists available at ScienceDirect Journal of Great Lakes Research journal homepage: www.elsevier.com/locate/jglr