LITTLE CURRENT – The United States Geological Survey (USGS) fisheries research vessel Sturgeon has just completed its counter-clockwise circumnavigation of Lake Huron and the months-long process of analyzing the data is now underway.
“We’ve found nothing that’s too shocking this year,” USGS supervisory fish biologist Timothy P. O’Brien told The Expositor when the vessel tied up in Little Current in early October.
“Since 2004, we’ve seen ups and downs with no real trend. If I had to identify one, over the last 10-15 years we’ve seen slightly increasing biomass (the total number of organisms in a given area) lake-wide, but that’s very slight,” said Mr. O’Brien. “There’s a lot of year-over-year variation and that’s normal.”
The annual survey saw the crew travel around Lake Huron and sample fish populations through sonar scans at prescribed collection points as well as mid-water trawling. The vessel has nets to capture fish as well as ultrafine mesh nets for plankton.
The populations this crew targeted were mainly prey fish, as a way of determining what abundance predator fish have available as food.
After gathering and analyzing the data, research teams will calculate the estimated number of fish in any given area in the lake using a metric called the index of abundance. This metric estimates either kilograms or pounds of fish per hectare of water and results will not be available for some months yet.
Mr. O’Brien added that reports on fish sightings from water users can be useful to help add context to their data, such as the reported increase in alewife near South Baymouth this year—an important prey fish for salmon populations.
The crew of the Sturgeon does nighttime sampling work and the vessel is based out of Sheboygan, Michigan, near Mackinac Island.