2015 a Productive Year at the Ontonagon River
Streamside Rearing Trailer
BY HENRY QUINLAN AND GLENN MILLER, ASHLAND FWCO
This past summer proved to be productive for the Ashland Fish and Wildlife Conservation Office (FWCO) in regards to the Streamside Rearing Trailer (SRT) on the West Branch of the Ontonagon River, Houghton County, Michigan. Located at the outlet of Lake Gogebic near Bergland, this was the third year the SRT was in place. Unlike the previous two years, when large volumes of spring run-off made egg collection on the nearby Sturgeon River near impossible, conditions in 2015 were favorable for egg collection. In two days, biologists from Michigan Department of Natural Resources, Ashland FWCO, Ottawa National Forest and the Fond du Lac Band of Lake Superior Chippewa Indians (FDL) were able to collect eggs from 8 females and milt from 32 males.
Following genetic guidelines for rearing and stocking sturgeon in the Great Lakes basin (http://www.glfc.org/pubs/SpecialPubs/2010-01.pdf), eggs and milt from lake sturgeon in the Sturgeon River were collected and combined to form 32 families. The fertilized eggs from each female are transported to the Ontonagon River SRT and placed into their own hatching jar. Ontonagon River water flows through the jars to gently tumble the eggs. The eggs and fish will imprint to this river water and seek to return to the Ontonagon River in the future. After a week the eggs hatch into tiny tadpole like sturgeon fry and shortly thereafter mini-lake sturgeon can be seen swimming in the tanks that will be their home for the next four months.
During the early days of life, the baby sturgeons are fed brine shrimp raised at the SRT. In three to four weeks, they reach about two inches in length and biologists begin to add shaved bloodworms for feed along with the brine shrimp. Eventually, the young sturgeons are converted to an all bloodworm diet.
During years like 2015, when eggs are plentiful and hatch rate is high, the number of fry and then fingerlings need to be “thinned out” to allow maximum growth in the tanks. In June about 8,500 fry were provided to FDL for release into the upper St Louis River by Brookston, Minnesota. This release is part of an ongoing restoration project to reintroduce sturgeon in this area. By mid-July, the fingerlings were three to four inches long and another 1,500 were provided to FDL.
After the final thinning, the remaining fingerlings are reared in the SRT until they are large enough to be marked internally with a tag the size of a grain of rice. These, Passive Integrated Transponder (PIT) tags have a unique identifier code which will allow for future study on the growth, movement, and survival of the stocked fish. This year, when stocking time approached, fish biologists from Ashland FWCO and ONF tagged 819 sturgeons composed of fish from each of the 32 families founded in May. On August 24th the SRT rearing season came to a close, with the seven to nine inch long fingerlings being released at two different locations on the main stem of the Ontonagon River, to help restore a genetically diverse lake sturgeon population in that river system.
The successful partnership among Tribal, State and Federal agencies and the Upper Peninsula Power Company is committed to a restoration effort on the Ontonagon River scheduled to last 15 – 20 years.
Over this time period eggs from up to 200 females could contribute to restoring a healthy lake sturgeon population in the Ontonagon River. Stay tuned for more!