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Roseman E.F.,Great Lakes Science Center | Manny B.,Great Lakes Science Center | Boase J.,USFWS Alpena National Fish and Wildlife Conservation Office | Child M.,Essex Region Conservation Authority | And 4 more authors.
Journal of Applied Ichthyology

Prior to the First World War, the bi-national Detroit River provided vast areas of functional fish spawning and nursery habitat. However, ongoing conflicting human uses of these waters for activities such as waste disposal, water withdrawals, shoreline development, shipping, recreation, and fishing have altered many of the chemical, physical, and biological processes of the Detroit River. Of particular interest and concern to resource managers and stakeholders is the significant loss and impairment of fish spawning and nursery habitat that led to the decline in abundance of most fish species using this ecosystem. Lake sturgeon (Acipenser fulvescens) populations for example, were nearly extirpated by the middle of the 20th century, leaving only a small fraction of their former population. Fisheries managers recognized that the loss of suitable fish spawning habitat is a limiting factor in lake sturgeon population rehabilitation in the Detroit River. In efforts to remediate this beneficial water use impairment, a reef consisting of a mixture of natural rock and limestone was constructed at the upstream end of Fighting Island in 2008. This paper focuses on the response by lake sturgeon to the different replicates of suitable natural materials used to construct the fish spawning habitat at Fighting Island in the Detroit River. Pre-construction fisheries assessment during 2006-2008 showed that along with the presence of adult lake sturgeon, spawning conditions were favorable. However, no eggs were found in assessments conducted prior to reef construction. The 3300m 2 Fighting Island reef was placed at the upstream end of the island in October of 2008. The construction design included 12 spawning beds of three replicates each consisting of either round rock, small or large (shot-rock) diameter limestone or a mixture thereof. An observed response by spawning lake sturgeon occurred the following year when spawning-ready adults (ripe), viable eggs, and larvae were collected during May and June 2009. Additional eggs and spawning-ready adults were found in 2010 (no larval sampling occurred in 2010) as well as collection of three age-0 juvenile lake sturgeon in bottom trawls fished downstream of the reef during July 2010. Spawning lake sturgeon showed no repeatable preference for any of the four particular substrate types but showed a high degree of preference for the island side of the channel, where faster water current velocities occurred. In 2009, overall lake sturgeon egg densities across all replicates averaged 102m -2 and seven larvae were found in night drift-net samples. In 2010, average lake sturgeon egg density was 12m -2 and three age-0 lake sturgeon averaging 120mm TL were collected in bottom trawls in deepwater (~8m depth) downstream from the constructed reef. These results demonstrated successful reproduction by lake sturgeon on a man-made reef and suggested that additions and improvements to fish spawning habitat could enhance reproduction and early life history survival of lake sturgeon in the Detroit River. © 2011 Blackwell Verlag, Berlin. Source

Roseman E.F.,U.S. Geological Survey | Boase J.,USFWS Alpena National Fish and Wildlife Conservation Office | Kennedy G.,U.S. Geological Survey | Craig J.,U.S. Geological Survey | Soper K.,Ontario Ministry of Natural Resources
Journal of Applied Ichthyology

In this report we describe how we adapted two techniques for sampling lake sturgeon (Acipenser fulvescens) and other fish early life history stages to meet our research needs in the Detroit River, a deep, flowing Great Lakes connecting channel. First, we developed a buoy-less method for sampling fish eggs and spawning activity using egg mats deployed on the river bottom. The buoy-less method allowed us to fish gear in areas frequented by boaters and recreational anglers, thus eliminating surface obstructions that interfered with recreational and boating activities. The buoy-less method also reduced gear loss due to drift when masses of floating aquatic vegetation would accumulate on buoys and lines, increasing the drag on the gear and pulling it downstream. Second, we adapted a D-frame drift net system formerly employed in shallow streams to assess larval lake sturgeon dispersal for use in the deeper (>8m) Detroit River using an anchor and buoy system. © 2011 Blackwell Verlag, Berlin. Source

Bouckaert E.K.,Michigan Technological University | Auer N.A.,Michigan Technological University | Roseman E.F.,U.S. Geological Survey | Boase J.,USFWS Alpena National Fish and Wildlife Conservation Office
Journal of Applied Ichthyology

Lake sturgeon (Acipenser fulvescens) were historically abundant in the St. Clair - Detroit River System (SCDRS), a 160 km river/channel network. In the SCDRS, lake sturgeon populations have been negatively affected by the loss/degradation of natural spawning habitat. To address habitat loss for lake sturgeon and other species, efforts are underway to restore spawning substrate by constructing artificial reefs. The main objective of this study was to conduct post-construction monitoring of lake sturgeon egg deposition and larval emergence near two of these artificial reefs: Fighting Island Reef (FIR) in the Detroit River, and Middle Channel Reef in the St. Clair River. An additional site in the St. Clair River where lake sturgeon spawn on a coal clinker bed was also investigated. From 2010 to 2012, viable eggs and larvae were collected from all of these reefs, indicating that conditions are suitable for egg deposition, incubation, and larval emergence. In the St. Clair River, the results indicate the likelihood of other spawning sites upstream of these artificial reef sites. Source

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