by Peter Jakey–Managing Editor
The Hammond Bay Biological Station (HBBS) in cooperation with the United States Fish and Wildlife Service are testing a new fish observation system.
The technical term for it is dual-frequency identification sonar (DIDSON).
In layman’s terms, scientists are using state-of-the-art equipment to conduct 24-hour surveillance on fish in northern Michigan rivers.
Mostly for the observation of the Great Lakes menace known as the sea lamprey.
“We propose to determine if DIDSON can be used to estimate adult sea lamprey abundance in medium and large rivers of the Great Lakes as a means to improve overall estimates of lake-wide adult sea lamprey abundance,” said Nick Johnson, HBBS research ecologist.
The aquatic invaders prey on commercially important fish species, living off of the blood and body fluids of adult fish. During its life as a parasite, each sea lamprey can kill 40 or more pounds of fish.
Work at HBBS has been a success story since the 1950s in controlling the organisms. Lake Huron levels are at 95 percent of their historical high, before sea lamprey control started. “That’s where we want to be,” said Johnson. “The cost to kill the extra 5 percent increases exponentially, as it gets harder to find a sea lamprey. The program is managed with economics in mind.”
Thus, this latest endeavor.
Cameras have been placed at the mouths of the Ocqueoc and Cheboygan rivers to monitor the movements of sea lamprey, as well as other fish species.
“It is a sonar image that produces video-like quality,” said Johnson.
DIDSON is capable of imaging fish at a distance of 40 meters in turbid water. Developed by the United States Department of Defense, DIDSON integrates assessment sonar with optical systems to generate video quality images in near zero-visibility water.
For the first time, researchers are going to be able to assess under completely natural conditions when fish are entering or leaving a river. They will record the time of day and year, and how it relates to water temperature and stream flow.
“And even where they are in the river, are they in the deep holes, or are they in the shallower sandy areas?” Johnson asked. “It will help determine when and where traps should be set.”
For valued fish, such as steelhead, researchers will be able to image the fish moving up river to spawn.
Last week, the Department of Natural Resources (DNR) planted small steelhead in the Ocqueoc and scientist are anxious to find out when they will leave the river to feed in the big lake. The information will be shared with DNR biologists.
“I fish a lot myself,” said Johnson. “It is the dream of a fishermen to see when and where fish are entering a stream, and what time of day. We also are learning a lot about sea lamprey behavior.”
Researchers want to remind boaters and anglers to be mindful of the equipment and to stay in the middle of the river when traveling in this location.
It is sophisticated equipment, but it does not have the capability to remotely transfer the video back to the station or stream it on the Internet. They have to go to the river and download it.
“We go out about once a day, or every other day to download the data,” said Johnson. “Then, at the biological station, we have a computer program that will watch the video for us, so to speak. It will highlight periods of time when there are fish moving through.”
The program measures the length and width of the fish, and how the fish is swimming to determine the species.
“We should even see smelt if they are moving in,” said Johnson.
“If our hypothesis is supported, DIDSON monitoring will provide previously undocumented insight into the natural timing of the sea lamprey spawning migration, which was highlighted as an important research priority of the 2007 sea lamprey assessment task force and could lead to novel trapping and control innovations.”
As a quality control measure, to ensure the equipment is operating properly, they watch video at specific times in the morning and night.
“We have small submerged buoys that are on the bottom of the stream. So, as long as we can see those buoys in the video, we know we are getting a high-quality image,” said Johnson. “The video from (Sunday) night, we saw 15 to 25 steelhead migrating up at night during a 20-minute period.”
Early on, scientists have been surprised sea lamprey have been entering the river while still frozen. Traditionally, the lamprey trap at the weir located near the Ocqueoc Outdoor Center does not start trapping lamprey until May.
“Most of what we know about sea lamprey migration timing is based on when we start catching them in traps,” he added. “For the first time now, we are actually seeing when they are coming in the river. What we are learning is there probably are a lot of lamprey in the river right now, but they are probably hidden under logs and rocks, and we are not able to catch them in traps because they are hiding out, waiting for warmer weather.”
This is a two-year study where they will operate the camera from mid-March to mid-June.
The project is funded by the Great Lakes Fishery Commission. Assisting locally in making it a success has been Melissa Pomranke and Samantha Nellis.
This year, HBBS will continue to use lamprey pheromones to lure them into traps. Pheromones are the odor that attracts females to a male’s nest.
Over the course of decades of work at HBBS, scientists have identified the pheromone chemical, and they intend to use it against the parasites.
“We will be baiting those traps with that pheromone to see if we can capture more sea lamprey,” said Johnson. “We are doing a more detailed study this year on different pheromone mixtures and also looking at trap designs on which trap works better.”
Last year, HBBS hosted Polish scientists in an experiment to electronically lure sea lamprey into traps. The technology showed substantial promise will be used in 2014 on two larger streams, one in Ontario and the other in Michigan.