This guest post is authored by Lynn Vaccaro from the University of Michigan Water Center
Fifteen years ago, a diverse group of researchers, scientists and passionate protectors of Michigan’s waterways got together to lay the foundation for what is now becoming a reality — large scale restoration of vital fish spawning habitat in the Detroit River. This loosely organized “restoration team” had a simple but bold idea – to address the practical challenges of building fish habitat structures in one of the world’s largest and busiest rivers.
The team – representing the University of Michigan Water Center, Michigan Sea Grant, DTE Energy, U.S Geological Survey, U.S. Fish and Wildlife Services, and Michigan Department of Natural Services – set out to construct fish spawning reefs that would replace the rocky habitat that had been lost in the river system and spur the recovery of native fish such as lake sturgeon – a state endangered species. Our story is featured in a recent front page article in the Detroit Free Press.
An interesting and not widely known part of Detroit River’s history, is that construction to support a growing transportation industry more than a century ago, had a severe impact on the river’s fish habitat. Beginning in 1873, miles of the river were blasted and dredged to create deep channels for large, commercial ships. When the dredged dirt, sediment and rocks were removed, the flow of the river changed, damaging the natural limestone reefs where millions of fish spawned. These and other impacts — including overfishing and shoreline development — dramatically reduced native fish populations, particularly lake sturgeon.
The restoration team built their first pilot spawning reef near the head of Belle Isle in the Detroit River in 2004. The project consisted of three small reef units, about 0.1 acres each, made of different materials. DTE provided the material for one of the three pilot reefs — coal cinders that were a by-product of a nearby power plant. This reduced the cost of this pilot project and helped the team demonstrate that a constructed reef was possible in the Detroit River.
Over the years, DTE Energy’s technical dive team – biologists who monitor water intake pipes and conduct ecological assessments for the company – contributed their time and unique expertise to support the reef project initiatives. This fall, DTE’s dive team conducted a survey of native mussels in three new areas being considered for reef development to ensure no native mussel were present that would be at risk in a new reef construction. Their in-kind support and expertise were valuable, as few divers in the region have the technical diving, mussel identification skills, and permitting connections to complete this type of work.
The restoration team is currently building a four-acre spawning reef in the three locations surveyed by the DTE dive team – very close to the original Belle Isle pilot project. DTE is again helping the team reduce construction costs, this time by providing a staging area at its retired Connors Creek Power Plant, located across from Belle Isle, where the reef rock is stockpiled and then loaded onto construction barges to be delivered to the reef.
The results of the team’s efforts became visible last spring, when lake sturgeon eggs were found on four different constructed spawning reefs in the Detroit and St. Clair rivers. This means sturgeon found the new habitat structures and deemed them suitable for spawning. Equally important, sturgeon eggs appear to be incubating and hatching successfully on the reefs, producing viable larvae that are showing up in nets downstream of the constructed reefs.
Despite massive population declines, the waterways connecting Lake Huron and Lake Erie continue to support the largest remaining population of lake sturgeon in the Great Lakes. Restoration efforts in these rivers could help rebuild native fish communities throughout the Great Lakes region, and this in turn benefits communities and the residents who live there.
For more information about the Belle Isle fish spawning reef project and our valuable partners, visit: miseagrant.umich.edu.