MDNR releases first tagged fish in a 5-year study that may Positively impact Platte Lake

The MDNR is conducting a clip and tag study for the first time on coho salmon that the PLIA will be closely monitoring. It is expected to be a five-year study (stocking 2026-2030). The study calls for two groups. Each group is tagged with a tiny wire containing a unique microscopic number. The first group of tagged fish were released in April at Eldorado Park on the lower Platte River.

Traditionally, all coho smolt reared at the Platte River State Fish Hatchery are released at the hatchery each Spring. These 4-6” salmon will then migrate downriver to Platte Lake and then further downriver to Lake Michigan. This out migration can take several weeks. These small fish have few defenses and are very vulnerable at this stage of their lives to predators such as birds and larger fish.

About half of the fish release will occur at the fish hatchery. Those fish will follow the same journey as their ancestors, down the river, through Platte Lake and eventually into Lake Michigan where they will live until returning to the river to spawn as three-year-old adults. The other half will be released at El Dorado Park downstream of Platte Lake. Those fish will have a shorter trip to Lake Michigan and likely a better chance of survival in the process. The survival and return rates of the two groups will be analyzed to help determine future direction of stocking in our watershed.

If the downstream group has a better return rate and the MDNR moves their release downstream, this could benefit Platte Lake in three ways. First, all of the smolt consumed by predators while in Platte Lake add to the biomass and our lake phosphorus concentration. Secondly, the MDNR may be able to raise fewer fish for the same result, which would save them time and money and reduce the amount of phosphorus produced at the hatchery. Finally, if successful, this could reopen the possibility of resuming the stocking of walleye in Platte Lake that was suspended in 2013 due to concerns of their predation of the coho smolt during out migration.

The PLIA worked closely with the Platte River State Fish Hatchery and MDNR on this project. Our first data point will be this Fall, when the two-year-old jacks follow spawning adults upstream to the hatchery. The following Fall, 2027, will be our first read on these fish returning as adults.  The process will be repeated each year until the MDNR is confident in the data and can form a conclusion as to which release method yields better results.

Here is a short video where we saw a demonstration of them tagging fish: