Field Notes Home

Field Notes

Normandeau-Developed HI-Z Turb’N Tag Aids USACE Scientists, Salmon at Chittenden Locks


For almost 50 years, Normandeau’s scientists have been at the forefront of fisheries management, merging traditional approaches with innovative technologies to meet client needs. Currently, members of the U.S. Army Corps of Engineers’ Seattle District are utilizing Normandeau’s proprietary HI-Z Turb’N Tag technology, to test the effectiveness of a prototype smolt slide being constructed in the Chittenden Locks. The series of 100-year old locks, part of the National Register of Historic Places, are vital to allowing commercial and recreational traffic from Lake Washington, Lake Union, and Salmon Bay to the Puget Sound. Fish passage thru the locks has long been a critical step in the migration of salmon, and the HI-Z Tag provides field researchers with a simple and efficient method for evaluating the health of a fish that has passed through the slide.

The Hi-Z Tag, first developed in 1990, is a small, inflatable balloon that can be safely attached and removed from a fish. To employ it, a trained and qualified user attaches the deflated HI-Z Tag to a young salmon before it is then released to travel through the slide. Once the salmon passes through the slide, the tag inflates, bringing the fish to the surface, where the user may conveniently and safely recover the fish to examine it for injuries. After examination and release, the previously tagged salmon swim on to the Puget Sound to continue their life cycle.

This innovative tag-recapture technique gives fisheries scientists a method of study which provides both high recapture rates and low mortality rates, all while having negligible effect on fish behavior and movement. The HI-Z Tag is ideal for projects that work with small sample sizes, limited budgets, or fish populations that vary in size and species, but is really applicable to any size project. It can be employed everything from small flood control structures with single or short fish ladders to large-scale hydroelectric plants with multiple or long ladders.

Normandeau, the Army Corps and other regional stakeholders are all looking forward to seeing the impact that the Hi-Z Tag data has on the study at the Chittenden Locks. If the smolt slide is successful, future salmon generations will have a new route to safely travel to the sea, providing further proof of the ability of natural resource management to thrive alongside commercial and recreational interests.

Talk to an expert.

Schedule a call with one of our scientists to discuss your next project.

Get Started