Case studies

Trout Pond Regeneration with Solar Aeration System

Solar powered aeration system for trout pond
Solar aeration system: cabinet and solar panel
Bubble Tubing Aeration line in trout pond
  • Solar powered aeration system for trout pond
  • Solar aeration system: cabinet and solar panel
  • Bubble Tubing Aeration line in trout pond

Private Trout Pond

Eastern Townships, Quebec

A case was presented to Canadianpond.ca where a trout pond had high organic matter input, high dissolved organic carbon and low dissolved oxygen concentrations. The goal of managing the pond was to improve water quality conditions for the trout population.

Trout Pond Regeneration with Solar Aeration System – short (1 page version for print – PDF)

Trout Pond Issue

The targeted issue for this project was to increase dissolved oxygen (DO) concentrations throughout the water column to expand trout habitat and improve overall water quality. The clarity of the lake was minimal due to a high dissolved organic carbon (DOC) concentration in the water, however algae growth was not an issue. This suggests that oxygen uptake in the lake comes from decomposition of older, possibly allochthonous, sediments rather than constantly regenerating algae. Reports from the owner suggested that the trout population was diminishing at an alarming rate with no obvious signs of fish kills. The disappearance of fish could have been linked to predation, however regardless of the cause, the lack of refugia within the trout pond was most likely the root of the problem.

Treatment

Dissolved oxygen concentrations throughout the water column before and after the installation of the solar powered aeration system fitted with Bubble Tubing™.Using this framework as a basis for further treatment options Canadianpond.ca sampled the lake prior to any treatment. Upon first sampling, it was found that the average maximum depth where dissolved oxygen concentrations were viable for trout was 1.8 m (6 ft) whereas the average depth was around 4 m (13 ft). Trout require a minimum of 4 mg/L of DO before they are subjected to oxygen stress. Also, because trout need relatively cold water to survive, the upper layers of the pond might pass the trout’s temperature threshold for survival in summer leaving only a small layer of habitable water conditions. Normally, trout move into the deeper water during these times, however, lack of oxygen could leave the trout with a very small habitat range and could easily lead to extirpation of the population.

Canadianpond.ca was limited in our options due to the lack of electricity at the site. Our solution was to add a solar powered bottom aeration system fitted with Canadianpond.ca’s Bubble Tubing™. The system was installed in the early summer of 2014 and follow up sampling was done later in the summer and again in 2015.

Results

Average temperature throughout the water column for summer months before and after the aeration treatment Dissolved oxygen showed a statistically significant improvement from before and after treatment in all sampled stations (p In order to check to make sure that most of the water column stays below 21 degrees, the average water temperature during the summer months was calculated throughout all of the sampling points and dates (see figure 2). As expected, there is much less stratification after treatment and the water at the bottommost depths is much warmer than before the treatment. Even though temperatures are warmer, the entire water column, except for the surface, remains under the 21 degrees Celsius required for the viability of the trout.

Conclusion

The treatment expanded the habitat of the trout by 55% to include the entire pond. Canadianpond.ca considers this project to have met all the goals defined meaning that this project has been a complete success.

References

Casselman, J. (2013) Haliburton’s Lake Trout: From the Past Into the Future. Presentation. Queen’s University, Kingston, Ontario, Canada.