Specialty Services

High Definition Fish Surveys (HDFS)

HDFS methods are a faster and lower impact option for T&E and recreational fish studies.

Fish studies can be time consuming, costly and inaccurate due to equipment associated with traditional electro-shocking or netting techniques. Netting and electro-shocking can also harm fish. Finally, such techniques merely indicate the presence of fish without showing them in their native environment. The HDFS technique is low-impact and will produce more information with more coverage over a shorter period of time. HDFS also documents fish in their native environment. Better information will lead to better recreational planning and preservation efforts.

Our Methodology
Trutta’s High Definition Fish Surveys (HDFS) use geo-referenced, underwater video cameras to visually document species occurrence, size, density and habitats. HFDS mobility and video documentation methods make it substantially faster and lower-impact than shocking or netting. HDFS has documented species from darters to smallmouth bass across the U.S. HDFS has also been used in conjunction with traditional methods.

Fishery Parameters:

  • Species present
  • Species size
  • Species number
  • Species biomass
  • Microhabitat conditions
  • Longitudinal distribution


Is your modeling accuracy hampered by limited bathymetric data?
Inaccurate or incomplete data will impair stream modeling accuracy. Trutta is experienced in collecting high-quality cross-sectional transect and bathymetric data over long stretches of water of all sizes. Combining this data with HDSS video footage and other data documented in an HDSS assessment expands modeling capababilities and accuracy.

Our Methodology
Transect data are plotted in ArcGIS to identify the cross-section points from HDSS longitudinal points. A line is created through the points and the points are snapped to the line. The cross-sectional data are then assembled with an ID (referring to the river mile), the water surface elevation, the vertical error associated with the water surface elevation, coordinate information for each point location, and the bottom elevation for each point. We collect cross-sectional transects at set intervals along the main channel and at tributary confluences and other hydraulically important locations.

Cross-sectional transects can be used for modeling purposes to estimate water quality at different water surface elevations or to determine how much stream bottom is inundated at different discharge amounts.

We can collect transect data from both kayaks or wading in any size stream.

HEC-RAS output associated with the Coosa River Bathymetry project.

Water Quality

A High Definition Stream Survey will collect water quality data over an entire stream corridor.
The traditional method of collecting water samples at a few locations in a stream corridor may indicate a problem exists but does not tell you why. The HDSS technique can collect samples at any frequency required over entire corridor stretches while simultaneously recording video and many other types of data. The ability to tie visual stream features with water quality trends makes it much easier and faster to identify areas where Best Management Practices (BMPs) can and should be applied to enhance stream health.

Our Methodology
Trutta’s HDSS methodology provides not only a much more thorough analysis of water quality (100% of the survey area, not randomly selected or just easily accessible spots), but also enables root cause analysis of water quality issues throughout a stream system. In short, HDSS can reveal changes in water quality that would likely not be revealed by relying on traditional sampling methods. For example, the algae blooms in Figure 2 below are an indication of too much nutrient runoff, as compared to healthy conditions just upstream (Figure 1). Traditional water quality samples taken short distances above or below this algae bloom would miss the fact that a dry swale (Figure 1, bottom right panel ) is obviously washing nutrients into the stream at high flow.

Figure 1: Dry swale on right side streambank entering an algae-free stream segment.
Figure 2. Just downstream of Figure 1. A bloom of filamentous algae is observed on the stream bottom.

Continuous water quality sampling at the confluence of the New River and Clear Creek, TN. The plot of water conductivity shows a marked difference in conductivity coming from the different water sources.

Map showing how specific conductivity increased downstream from a creek confluence on Falling Water River in TN. Red dots indicate where kayaks were portaged over large log jams. Combining the water quality results with the HDSS video allows anomalies such as these to be easily understood.

The Mighty Oak Pathway

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