Does Fish Stocking Contribute to Algae Bloom and toxins?
Several concerned residents of Summit Lake questioned whether or the repetitive stocking of fish and fingerlings into Summit Lake may contribute to the algal blooms and ultimate toxicity of Summit Lake. These residents have cited studies linking the stocking of fish to the rise of phosphorus levels in fresh water lakes. Phosphorus is a well documented contributor to the rise in algal blooms which can lead to toxic algae blooms.
According to recent studies, fish stocking contributes to the rise of phosphorus levels in lakes and could be one of the sources of our problem with algae blooms turning toxic. The Department of Fish and Wildlife dumped approximately 40,000 fish into Summit Lake between April 7th and May 8th this spring. The schedule provides that they were also stocking Summit Lake with about 225,000 fingerlings in either May or October. The lake was tested and declared toxic on or about May 7th, 2017. Below are links to the fish stocking schedule from the Department of Fish and Wildlife.
http://wdfw.wa.gov/fishing/plants/weekly/regions.php?region=6 ( or See Attachment - Number of catchable fish stocked)
http://wdfw.wa.gov/fishing/plants/statewide/ ( or See Attachment – wdrw01900 2017fingerling stocking)
About 23 concerned residents of Summit Lake, (not the Summit Lake Community Club organization) signed and mailed two letters that went out to the Governor and to the Department of Fisheries on June 22nd, 2017 stating their concern that the fish stocking could be contributing to our problem and asking that the stocking be halted until we can determine what impact the fish stocking may be having on our lake and drinking water. The concern over fish stocking contributing to rises in phosphorus levels is corroborated by at least 3 sources that we have consulted these last few weeks.
http://onlinelibrary.wiley.com/doi/10.1002/ecs2.1554/epdf
In summary, the study states that the fish are fed food high in nutrients. The fish then excrete these nutrients/phosphorus into the lakes at high levels. Even small increases in Phosphorus loads boost the occurrence of algal blooms, which over time, can result in a lake with high nutrient levels or eutrophication. Eutrophication is the process by which a body of water becomes enriched in dissolved nutrients (such as phosphates) that stimulate the growth of aquatic plant life usually resulting in the depletion of dissolved oxygen. The algal blooms eventually die and in their decomposition, microbes process the dead material. The microbes require huge amounts of Oxygen and the lake becomes hypoxic, an oxygen poor aquatic climate. Other life-forms are deprived of Oxygen. They die and the algae multiply because they feed on the phosphorus. In doing so, they use a lot of oxygen and create dead spots and toxins.
According to their website, The Department of Ecology Water Quality Program’s mission is to protect and restore Washington waters to sustain healthy watersheds and communities. Their work ensures that state waters support beneficial uses including recreational and business activities, supplies for clean drinking water and the protection of fish, shellfish, wildlife and public health. The Department has grants and training to obtain grants listed on their website.
http://www.ecy.wa.gov/programs/wq/funding/funding.html
According to recent studies, fish stocking contributes to the rise of phosphorus levels in lakes and could be one of the sources of our problem with algae blooms turning toxic. The Department of Fish and Wildlife dumped approximately 40,000 fish into Summit Lake between April 7th and May 8th this spring. The schedule provides that they were also stocking Summit Lake with about 225,000 fingerlings in either May or October. The lake was tested and declared toxic on or about May 7th, 2017. Below are links to the fish stocking schedule from the Department of Fish and Wildlife.
http://wdfw.wa.gov/fishing/plants/weekly/regions.php?region=6 ( or See Attachment - Number of catchable fish stocked)
http://wdfw.wa.gov/fishing/plants/statewide/ ( or See Attachment – wdrw01900 2017fingerling stocking)
About 23 concerned residents of Summit Lake, (not the Summit Lake Community Club organization) signed and mailed two letters that went out to the Governor and to the Department of Fisheries on June 22nd, 2017 stating their concern that the fish stocking could be contributing to our problem and asking that the stocking be halted until we can determine what impact the fish stocking may be having on our lake and drinking water. The concern over fish stocking contributing to rises in phosphorus levels is corroborated by at least 3 sources that we have consulted these last few weeks.
- A study conducted by the ESA (Environmental Society of America) in 2016 conducted testing of both residential and non-residential lakes over a several year period. It showed that the levels of phosphorus rose considerably in the lakes that had fish stocked in their lakes. The study even found that the stocked lakes with residential development did not vary significantly from lakes with stocked fish with no residential development. (Meaning to this writer that the residential development didn’t contribute as much as the fish!) See the study in the link below.
http://onlinelibrary.wiley.com/doi/10.1002/ecs2.1554/epdf
In summary, the study states that the fish are fed food high in nutrients. The fish then excrete these nutrients/phosphorus into the lakes at high levels. Even small increases in Phosphorus loads boost the occurrence of algal blooms, which over time, can result in a lake with high nutrient levels or eutrophication. Eutrophication is the process by which a body of water becomes enriched in dissolved nutrients (such as phosphates) that stimulate the growth of aquatic plant life usually resulting in the depletion of dissolved oxygen. The algal blooms eventually die and in their decomposition, microbes process the dead material. The microbes require huge amounts of Oxygen and the lake becomes hypoxic, an oxygen poor aquatic climate. Other life-forms are deprived of Oxygen. They die and the algae multiply because they feed on the phosphorus. In doing so, they use a lot of oxygen and create dead spots and toxins.
- One of the lake residents e-mailed the Department of Ecology and asked them to consider the ESA report cited above and inquiredwhether the Department knew whether or not there was a link to the fish stocking and toxic algae. One of the Biologists with the Department of Ecology who has a PhD and works in the Water Quality Program, emailed back and reported that she had been asking lake management people for years to ask WDFW to stop or reduce the stocking rates at least until they can figure out what is really going on in some of the lakes that are having cyanobacteria blooms. She suggested that we contact the Department of Fisheries to request that they cut back or stop stocking the lake. This same Doctor also advised that lake resident that she requested that a consultant do a preliminary study on the correlation between stocking and blooms, but advised that this would not get started until next year.
- Several members of the Summit Lake Community Association met with the Herrera Environmental Consultants within the last few weeks. They reported back that Herrera also said that fish stocking was a contributor to rising levels of phosphorus and that it could be a factor in our blooms.
According to their website, The Department of Ecology Water Quality Program’s mission is to protect and restore Washington waters to sustain healthy watersheds and communities. Their work ensures that state waters support beneficial uses including recreational and business activities, supplies for clean drinking water and the protection of fish, shellfish, wildlife and public health. The Department has grants and training to obtain grants listed on their website.
http://www.ecy.wa.gov/programs/wq/funding/funding.html