Large amount of fish die in Bischoff Reservoir
DEBBIE BLANK THE HERALD-TRIBUNE Apr 17, 2020
“We counted 120 (dead) fish just on our shoreline” on the northern edge of the reservoir’s finger in Morris, said Dr. Trent Austin. It’s the most dead fish he’s seen at one time since living on Bischoff Reservoir.
The dead shad filled Dr. Trent Austin’s wheelbarrow. How should landowners dispose of dead fish in their yards? Marty Benson answers, “Usually the wildlife will consume most of the dead fish; however, if landowners wish, they can dispose of the dead fish in the trash. Burying them is another method of disposal.”
“There’s a big fish kill” at Bischoff Reservoir in Batesville, adjacent landowner Dr. Trent Austin reported April 15. His theory on why it happened: “We had a sudden warmup in weather, (people) dumped fertilizer on their yards,” then rain washed nutrients into the reservoir.
“Blue-green algae ... are a group of photosynthetic bacteria found in lakes and slow-moving streams,” according to the Indiana Department of Environmental Management website https://www.in.gov/idem/algae/.
“Increased phosphorus and nitrogen (nutrients) from fertilizers, warm weather and low turbulence cause them to ‘bloom’ in large numbers. Phosphorus is particularly important in fueling their growth.
“When algal blooms die off, they sink to the bottom. The degradation of this organic matter consumes available oxygen in the water. This depletion of oxygen may be great enough to result in fish kills.”
Austin confirmed, “Fish were swimming around gulping for air. Thousands of fish washed up on the shore, bloated and stinking.”
Marty Benson, Indiana Department of Natural Resources Division of Communications assistant director, believes the dead fish are the result of a different cause. He explains, “In Indiana there are several natural types of die-offs, such as this one, over the winter and into early summer. We refer to them as die-offs, to attempt to distinguish them from fish ‘kills’ that are caused by anything unnatural, such as chemical releases/discharges/accidents.”
“This particular incident appears to be a typical, natural die-off of shad. Fertilizers can contribute to algal blooms, especially in late summer. These algal blooms can affect dissolved oxygen in a body of water (especially when a large bloom dies, and dissolved oxygen is consumed during its decomposition) and cause natural die-offs, but that doesn’t happen this early in the year in Indiana.”
Benson told why the shad died. “Normally, fish have enough fat reserves going into winter to make it through; however, very cold water temperatures can exhaust those reserves, especially in smaller fish. Shad feed on plankton, which is in very low abundance toward the end of winter. The combined stressors of depletion of fat reserves, lack of food and temperature swings on already stressed fish can result in the death of large numbers of shad.”
If blue-green algae does grow unchecked in Hoosier lakes, they can be dangerous. IDEM reports on its website, “Some blue-green algal strains produce toxins, threatening human and animal health. In extremely rare instances, toxin-producing blue-green algae have resulted in the sickness or death of animals, including livestock and particularly dogs.”
“If you are recreating in a lake or other waterbody, don’t ingest the water, avoid contact with visible algae or algal scums, and shower or bathe with warm, soapy water when you are finished. If you think you are ill from contact, you need to contact your doctor for assistance and to report a human illness. Veterinarians recommend not allowing pets and livestock to drink or swim in waters affected by algae.”
Austin says he’d like to increase awareness about the effect fertilizer can have on lakes. He hopes his neighbors “can tolerate a yard that’s a little less green” in exchange for cleaner waterways.
The Indiana Department of Environmental Management has these tips to reduce or stop nutrient inputs in waterways:
• Most established lawns do not need phosphorus to be healthy. If applying fertilizer, use a phosphorus-free lawn fertilizer. This is critical if you live on a lake. Lawn-fertilizer packaging is labeled with three numbers for nutrient content. A zero as the middle number (phosphorus content) indicates a phosphorus-free fertilizer.
• Do not overfertilize in your garden. Check soil nutrient levels prior to applying garden fertilizer to ensure correct application. Soil test kits can be purchased from some local hardware stores and through online distributors.
• Do not fertilize up to the waterway’s edge. Check with your local government for any specific setback requirements.
• Do not dispose of grass clippings or leaves in or near a waterway.
• To prevent inputs from human waste, have your septic system inspected and tank pumped out at least every two years.
• If conducting land-disturbing activity, prevent soil and organic matter from washing into waterways, as soil can carry nutrients into the water.