Coho and Chinook Salmon are not native to the Great Lakes. They were introduced into the Great Lakes in the 1960s by the Michigan Department of Natural Resources (DNR) in an attempt to solve two problems.
The native population of Lake Trout was nearly extinct due to a combination of overfishing and predation by non-native Sea Lampreys. Also, populations of a non-native fish the alewife exploded in the Great Lakes. Alewives frequently experienced seasonal die-offs as they exhausted food supplies. Their bodies would then wash up on Great Lakes beaches making them inhospitable. Both Sea Lampreys and Alewives were introduced to the Great Lakes when the Welland Ship Canal.
By introducing Salmon, the DNR hoped to revive the Great Lakes sport fishery and reduce Alewife populations to an acceptable level. The introduction was a wild success. Today, Salmon remain a popular sport fish in the Great Lakes.
Great Lakes Coho and Chinook Salmon sped most of their lives swimming in the open waters of the lakes. At the age of three, they return to rivers to spawn. After these salmon spawn they die just like all Pacific Salmon species; Atlantic Salmon live after after spawning and return to the ocean.
When salmon were first introduced in the Great Lakes this caused a huge problem in Traverse City. Four dams spanned the river preventing salmon from migrating far upstream (one of these dams has been removed and two others are slated for removal). This meant that when the salmon spawned and consequently died they did so within the city limits of Traverse City. Saying that the resulting smell was unwelcome is an understatement!
The solution was to build a harvest facility to collect salmon from the river before they could spawn and die. This facility, known as the Boardman River Weir, consists of a weir that blocks passage upriver, a fish ladder that leads to a series of survival tanks, and a building that contains sorting tables and other equipment for processing the fish.
|The weir allows water downstream, but blocks fish from traveling upstream|
|The fish ladder is staggered to allow salmon to rest before swimming up each spillway.|
|The holding tanks and fish ladder a fenced off to prevent people from taking salmon.|
|Inside the building, processing tables are used to sort salmon for shipping to distributors. Tubes lead to a recovery tank so trout, steelhead, and Atlantic Salmon collected in the weir can be returned to the river.|
|Carbon Dioxide and Oxygen are used as an anesthetic to calm the fish so they can be handled for processing. The basket on the right is used to lift the anesthetized fish up onto the sorting tables.|
|The number of salmon (and other species) collected are recorded and posted so the public can see what is happening. Windows look in on the processing facility|
During the fall salmon run, staff from the Michigan DNR is on site to answer questions and give tours of the facility. We are lucky enough to know several of the DNR employees at the weir and we were allowed to stay inside the fence taking photos as long as we wanted.
|Once in the holding pens salmon just cruise around as there is nowhere further upstream for them to go. Occasionally one will jump up out of the water, sometimes even landing on the concrete walkway.|
|The weir spans the entire river, blocking passage upstream upstream, but allowing water through|
|Despite the barrier, a small number of salmon jump over the weir and continue upstream.|
|Debris has to be removed from the weir periodically so water can flow through. If the water flows over the weir salmon will be tempted to jump over instead of entering the fish ladder.|
|The view of the facility from the weir.|
While we were watching several fish attempted to make their way up the fish ladder. Some of the fish had an easy time; others struggled to make it upstream. The staggered spillways ensure that there is an area of slack water at each level, allowing tired fish to rest before ascending to the next level.
|This salmon just swam up the ladder|
|This salmon jumped up the spillway to the next level.|
|The bright sunlight made it easy to see the salmon as they swam around the holding pens.|
Unfortunately not every salmon that makes it up the fish ladder survives until harvest. Some salmon are simply too exhausted and beat up by their journey. When that happens the dead fish are removed from the pen and disposed of.
|DNR employee Francis Majszak gaffs a dead salmon and removes it from the holding pen at the Boardman River Weir.|
|This dead salmon had a surprise. That's a juvenile Sea Lamprey attached to its tail fin.|
|A closer view of the juvenile lamprey. Because the Sea Lamprey is an invasive species it was destroyed rather than being returned to the river.|
If you would like to learn more about the Boardman River Weir, the brochure shown below can be downloaded from the Michigan DNR. The fish weir typically remains in operation through October. It's only a 2 hour drive from Mid-Michigan and is a great place to visit while in the Traverse City area, especially when combined with a fall color tour of the Old Mission Peninsula, Leelanau Peninsula, or Sleeping Bear Dunes National Lakeshore.