Streamside incubator could help restore shade to Michigan

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A remote site incubator in Montana. Image: Glenn Boltz, US Fish and Wildlife

By Danielle James

As several groups of researchers race to bring grayling back to the Great Lakes, one program recently received major help with a $70,000 grant.

The project hopes to find the best design for an incubator to produce the fish that has not been in Michigan waters since 1936. It is part of a multi-phase effort by the Michigan Arctic Grayling Initiative, a collaboration of over of 40 partners to make fish self-sufficient in the Great Lakes.

“Northern Michigan University looks forward to collaborating on this project with Michigan DNR,” said Brandon Gerig, assistant professor of biology at Northern Michigan University. “It’s exciting that the data generated by this project is directly informing arctic grayling restoration efforts in Michigan.”

The grant will be used to assess the success of remote site incubators, according to the Department of Natural Resources. They are testing the alternative to hatcheries, which spawn and rear fish in artificial environments.

Instead of using hatcheries, remote site incubators hatch eggs at the edge of the stream and allow fish to move directly into the water, according to a study led by Alan J. Mock, a researcher at the Institute of Annis Water Resources from Grand Valley State University.

Hatcheries are commonly used to supplement wild fish stocks, but can lead to lower reproductive success and survival rates, according to his research.

According to Mock’s research, raising fish in more natural conditions could allow them to acclimate better and improve their survival rate after release.

Arctic grayling was the only abundant river salmon family fish present in the Lower Peninsula until the 1930s.

Shadow. Image: State of Michigan

But logging, overfishing and the introduction of more competitive trout species have caused the grayling to decline. The last recorded fish in Michigan was caught in 1936, according to state resource agency data.

Past attempts to reintroduce grayling to Michigan included stocking hatchery-raised fish in lakes and streams from the late 1800s through the 1980s, according to the department’s website.

But previous efforts have failed.

This new project is the second funded by the Consumers Energy Foundation, said MNR Fisheries Division Chief Jim Dexter.

“Through their partnership, we are able to move closer to our goals and experience success,” Dexter said.

The first consumer grant created a system for rating Michigan stream habitats and their shade compatibility. The Manistee River watershed was chosen as the first reintroduction site.

Similar research involving Grayling is currently being conducted in Canadian rivers by University of Alberta researcher Heather Veilleux.

The project is looking at eDNA, or genetic material that spreads through the environment, Veilleux said.

“Every living organism has DNA and it is widespread in water, air or soil,” Veilleux said. “The idea with eDNA, especially in the aquatic realm, is that you can take a spoonful of water and select the part of the DNA that you’re looking for in that species.

Veilleux said his research tested eDNA in streams to identify juvenile grayling, which is harder to find by traditional methods.

She hopes to use her data to find where the shadows spawn and bring more eggs to those areas.

The Michigan initiative also hopes to increase juvenile populations, but bases the new project on remote site incubator designs that have worked for grayling in Montana.

Their success is less certain in Michigan streams, according to the DNR.

But Grand Valley State University conducted similar research with Michigan rainbow trout in 2018, according to Mock’s research. Researchers were concerned that sandy streams in the Midwest would hamper survival rates in incubators.

Three tributaries of the Manistee River were tested with rainbow trout eggs.

The different types of incubators did not affect performance, and Michigan’s hatching success rate was similar to that of Montana. The overall survival rate for rainbow trout was 41.3% in 2018 and 52.4% in 2019, compared to 45% for grayling eggs in Montana.

No matter where they are, arctic graylings are very sensitive to environmental stress, Veilleux said.

“Changes in temperature, salinity, contaminants and habitat fragmentation, such as during culvert construction, all affect them,” she said. “And they are listed as a species of special concern under Alberta wildlife laws.”

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