End-of-summer means more fish kills statewide


The end of the summer is when fish are most vulnerable to changes in their environment, so even a small amount of pollution can cause major fish kills in Iowa’s waterways. (flickr/AgriLife Today)

The state Department of Natural Resources warns Iowans to consider how fish are affected when using chemicals and fertilizers.

The end of the summer is when fish are most vulnerable — temperatures are high, and dying and decaying plant life reduce dissolved oxygen in the water. Fish and other aquatic wildlife are stressed, meaning pollution can lead to more fish kills.

In 2016, the DNR reported 15 fish kills, 11 of which occurred in the latter part of the summer, after July 15. In the last two weeks, the DNR has investigated four fish kills around the state.

The DNR reminds farmers and homeowners that what they put on their fields or lawns will wash into waterways, where it could harm wildlife. Even a small amount of a chemical can cause serious damage.

“We have received several reports of small summer fish kills at many lakes, ponds, and a few streams throughout Iowa,” said Chris Larson, fisheries supervisor for the DNR in southwest Iowa, in a press release. “We have also had some fish kills caused by pollutants.”

Rarely, however, will all of the fish in a single body of water die at once. Usually the ecosystem can bounce back from a fish kill and balance its population again within a few years.

Farmers and homeowners can prevent pollution-caused fish kills by not applying chemical fertilizer or manure before it rains, and following disposal instructions on pesticide labels.

Spawning stress fish kill in Tama County


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More than 1,000 black crappies were reported dead at Lake Casey yesterday due to spawning stress. (Georgia Aquarium
Jenna Ladd |June 8, 2017

A fish kill has been reported at Casey Lake in Tama County. More than 1,000 black crappies were reported dead at the Hickory Hills Park Lake yesterday. Crappies are a North American freshwater sunfish that are indigenous to Iowa. Fish kills can be caused a number of factors including pesticide contamination, high temperatures, algal blooms and more.

“When we get calls about one species of dead fish during the spawning season, it is usually caused by spawning stress,” said Dan Kirby, fisheries management biologist for the Iowa Department of Natural Resources (DNR). Like many freshwater fish, crappies move closer to the shoreline to spawn in the late spring and early summer. Spawning activities require fish to expend a lot of energy, leaving them susceptible to infections and illness. It is common for spawning fish to sustain abrasions from jagged rocks and debris at the water’s edge. These cuts and scrapes are vulnerable to infection that can cause death. Typically, spawning stress fish kills occur slowly over the course of weeks. It is unclear how long the fish at Casey Lake were piling up near shore.

“Fish surveys conducted this week on Casey Lake showed that largemouth bass and bluegills are doing well, and black crappies are abundant,” Kirby added.

Iowa DNR encourages residents to call their 24-hour phone line at 515-725-8694 if they notice dead fish accumulating in lakes or rivers.

Iowa DNR suspects farm crop duster is responsible for Medapolis fishkill


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(Florida Fish and Wildlife/Flickr)
Jenna Ladd | August 3, 2016

The Iowa Department of Natural Resources suspects that crop duster farm chemicals are responsible for killing thousands of fish in a southeast Iowa creek late last week.

A local resident near Mediapolis discovered the dead fish last Friday, July 29th and notified authorities. When investigators arrived they found a five-to-six mile stretch of the Cedar Fork Creek to be littered with slain freshwater species of all kinds including bass, catfish, crayfish, sunfish and chubs. Short sections of Flint Creek were also affected.

DNR quickly ruled out fertilizer or manure spill as potential causes. Ryan Stouder, environmental specialist with the organization says he’s confident that crop duster farm chemicals are the culprit,“The Department of Ag pesticide investigator is pretty confident it is, just off the visual signs of mineral oil in the water.” Investigators are unsure if the contamination was the result of unintentional drift or an emergency aerial dump. Water samples were collected from the scene in order to determine specific chemicals present. If a source can be identified, DNR will take appropriate enforcement measures.

The Iowa Department of Agriculture joined DNR in further investigation on August 2nd.

Illinois bans microbeads; other states may follow


Atlantic Salmon. Photo via Eric Kilby; Flickr
Atlantic Salmon. Photo via Eric Kilby; Flickr

Illinois has become the first state in the nation to ban microbeads, the small plastic particles found in many soaps and skin care products.

Recent research found that most microbeads are too small to be detected by water filtration systems. This allows them to reach lakes and rivers, where they attract pollutants in the surrounding water. They are then consumed by fish, who confuse the plastic beads with fish eggs. If these fish are then consumed by humans or other wildlife, the toxins are able to spread throughout the food chain.

Researcher Sherri Mason found up to one million of the tiny pellets per square kilometer in areas of the Great Lakes.

Illinois is requiring manufacturers to phase out microbeads by the end of 2017. Some companies are already investigating biodegradable alternatives.

Illinois governor Pat Quinn hopes that the rest of the nation will follow Illinois’s example. There is a similar bill pending in New York, and legislators are taking action in Minnesota, Ohio, and California as well.

Concerned consumers should avoid purchasing products listing polyethylene or polypropylene among their ingredients.