Graham Sustainability Institute

Science in Action - Restoring Fish Habitat in Urban Rivers

Wednesday, November 18, 2015

Next spring, native fish, such as lake sturgeon, will have more places to spawn and safely incubate their eggs in the Detroit River. To compensate for historic habitat losses, Water Center specialists are helping to build a 4-acre fish spawning reef offshore from Wyandotte, Michigan. Although simple in concept, the planning and implementation of this restoration project has taken three years and the design draws upon many years of research. As the team facilitators, Water Center specialists help integrate the knowledge of biologists, engineers and stakeholders to ensure that restoration decisions are based on sound science while meeting management and other stakeholder needs.

Engaging Key Stakeholders

The new Detroit River spawning reef is a long narrow bed of loose rock, approximately 2 feet thick. The rock is placed on the river bottom by a marine construction company working from a barge with a crane and clamshell. Although the reef is below 26 feet of water, 3800 feet from the mainland, and 200 feet from a navigation channel, the restoration project required an extended consultation and approval process involving the Detroit River Area of Concern Public Advisory Council, shoreline property owners and the Lake Carriers Association, which represents the domestic Great Lakes commercial fleet. Water Center specialists recently organized a boat tour of the restoration site to thank supporters and invited along some representatives of the media.

See: Environment Report Story

Balancing Competing Uses

Understanding different human uses of a river is an important part of planning a successful restoration project. In August, Water Center specialists organized a ride on a commercial freighter through the St. Clair and Detroit Rivers for members of the project team. The trip provided a unique opportunity to consult with the ship captain, crew and industry representatives, and observe how freighters operate and navigate through different parts of the river system. This experience allowed the team to design and secure approval for a small test reef that will be built offshore from historic Fort Wayne in the Detroit River in late fall 2015. The test reef will be used to characterize potential impacts from commercial freighters at this site and aid in the design of future restoration projects in areas with heavy ship traffic.

Showing Results

This summer, the restoration team got some exciting news: sturgeon eggs were found on two reef projects constructed in the St. Clair River in 2014. Pre- and post-restoration monitoring is an essential part of the team’s adaptive management process. Egg collections showed an increase in sturgeon egg deposition from 0 (before restoration) to more than 2,000 eggs per square meter in the first spawning season after reef construction. On-going monitoring is assessing the larval fish produced by eggs on reef. Field work is led by collaborating biologists from the USGS Great Lakes Science Center, US Fish and Wildlife Service, the University of Michigan and Michigan Department of Natural Resources. When possible, graduate students get involved to tackle emerging issues. For example, a student supervised by Jim Diana, School of Natural Resources and the Environment, found that a state endangered catfish, northern madtom, is also using the constructed spawning reefs for shelter and probably for spawning during the summer. 

See: Conrad’s Thesis 

A Long Process

In the Great Lakes region, the St. Clair and Detroit Rivers historically served as some of the most important spawning grounds for fish species such as lake sturgeon, walleye, lake whitefish and cisco. However, many of the natural limestone reefs and rocky areas were destroyed when shipping channels were constructed, or upland land-use changes resulted in too much silt entering and clogging the system, and similar, rocky, spawning areas in tributary rivers were made inaccessible as a result of dams.

In 2001, Water Center Director Jennifer Read began working with a consortium of state and federal partners to implement strategies for re-creating rocky spawning habitat in the St. Clair and Detroit River System. The team is using an adaptive management process to design and study a series of spawning reefs so that subsequent projects incorporate lessons learned. The Water Center role, serving as team facilitator, ensures that decisions are based on sound science and incorporates the group’s collective best judgement, and that design, permitting and construction work reflects these decisions. The Water Center also works closely with Michigan Sea Grant on targeted outreach efforts.

See: Project Webpage