A trio of PNNL fish researchers recently published a video journal article on how to properly implant miniature acoustic tags in juvenile Pacific Lamprey and American Eel and how the tags could benefit migration.
The video journal details laboratory trials using the tags from PNNL's accredited Bio-Acoustics & Flow Laboratory. The tags, part of PNNL JSATS’s tracking suite, track the lamprey and eel and provide information about their behavior near hydropower dams.
The trials conducted on juvenile lamprey and eel indicate that the tags can be successfully implanted on both species without affecting their swimming ability or survival. There also is minimal tag loss over the tag life of 30 days.
A decline in fish numbers
As the population of the Columbia River Basin’s lamprey has declined over the past 40 years, experts have been researching ways to preserve the species near hydroelectric facilities, specifically dams. Juvenile lamprey migrate deeper in the water column than juvenile salmon and are less likely to pass through the juvenile bypass systems. This makes it more difficult to detect the species and gather information with other types of tracking transponders. However, learning about lamprey behavior and survival is important for developing mitigation strategies for downstream passage, including bypass system design for use at dams.
Like the lamprey, the American eel population has dramatically declined over the past several decades. The once-abundant species has dropped by 50 percent in Chesapeake Bay and by as much as 97 percent in Lake Ontario, according to reports by others that the researchers cited. The species is currently listed as endangered under the Ontario (Canada) Endangered Species Act. The development of hydropower facilities also has created obstacles for eels, which swim downstream.
A tag solution
Before PNNL’s development of the micro acoustic tags, tags were too large to be successfully implanted in the body cavities of juvenile lamprey and eel. PNNL’s micro acoustic tag is small and easy to implant. It measures 12 millimeters in length by 2 millimeters in diameter and weighs 0.08 grams in air. The implantation of the tags doesn’t require sutures and involves a small incision of less than 3 millimeters in length. The lamprey/eel tags emit unique coded signals, which are monitored through autonomous receivers, or hydrophones, at fixed structures or in-river receivers..
The team determined the tag did not affect or change the lamprey or eel’s swimming ability. Less than 3 percent of the lamprey lost tags and 3.8 percent of the eel lost their tags, researchers reported. None of the lamprey or eel died during the 38-day holding period.
PNNL’s technology provides scientific information that can be used to develop strategies or designs for downstream passage.
For more information on obtaining a license for the eel and lamprey tag, contact Sara Hunt, PNNL technology commercialization manager.