Natural factors causing trout die-off at Shepherd of the Hills

A combination of natural factors has led to a trout die-off at the Missouri Department of Conservation's Shepherd of the Hills Hatchery in Taney County. Some of the fish are being temporarily transferred to other hatcheries in the state until water conditions at Shepherd of the Hills Hatchery improve.

Rapid response by MDC statewide hatchery staff mitigating loss.

BRANSON, Mo. – An unfortunate combination of late-autumn water conditions has caused a die-off of trout at the Missouri Department of Conservation’s (MDC) Shepherd of the Hills Hatchery.

This fish loss is a result of a combination of current environmental conditions that include warm water, low oxygen, high nitrogen, high sulfur levels and excess nutrient content. Hatchery staff will not know the full impact of trout loss for some time as some fish may experience delayed mortality from the stress they experienced at this time. Mortality has occurred in all sizes of fish at the hatchery. Shepherd of the Hills Hatchery, located in Taney County, is Missouri’s largest trout hatchery. It produces 1,250,000 trout annually which are stocked into Lake Taneycomo and other trout areas around the state.

Much of the above-mentioned environmental conditions can be traced to the heavy rains, hot temperatures and algae die-off that depleted water quality and caused fish die-off problems at Table Rock Lake this past summer. Shepherd of the Hills receives its water from Table Rock.

Fortunately, quick action by MDC hatchery staff is resulting in the bulk of Shepherd’s trout population being saved. Some are being moved to other raceways at the hatchery where the water quality is better; other trout are being temporarily transported to Bennett Spring Hatchery, Montauk Hatchery and Lost Valley Hatchery.

The primary cure to Shepherd’s problems will occur when cold weather arrives.

“The faster it gets colder, the sooner the water temperature at the surface (of Table Rock) will equal the water temperature at the bottom (of the lake) and allow the lake to mix,” said MDC Fisheries Management Biologist Shane Bush, who oversees fish management at Table Rock and Taneycomo reservoirs. “This will bring better water quality through the dam. This may happen as soon as this weekend with cold temperatures expected.”

The hatchery’s Conservation Center remains open to the public from 9 a.m. to 5 p.m. daily, but trout viewing opportunities along the raceway have been temporarily closed to the public.

More information can be obtained by calling the Shepherd of the Hills Hatchery Conservation Center, 417-334-4865 or the Missouri Department of Conservation’s Southwest Regional Office in Springfield, 417-895-6880.

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MDC explains winter fish kills are no cause for alarm

Aerial photomosaic of the Lake of the Ozarks in Missouri (Photo credit: Wikipedia)

Common seasonal phenomenon is more widespread this year due to unusually severe winter.

JEFFERSON CITY, Mo. – The sun comes out and the temperature climbs bravely into the 40s. You shake off cabin fever with a stroll around a lake or pond and through the neighborhood. Birds are singing and the fish in the pond are… dead!

People all over Missouri are calling Missouri Department of Conservation (MDC) offices with stories like this one. They are sad to see dead fish and concerned about what might be killing them. The Department of Conservation appreciates callers’ vigilance, but officials say the fish die-offs documented so far are not related to serious pollution or disease issues.

MDC Resource Scientist Rebecca O’Hearn says winter fish kills are normal occurrences. What is not normal, she says, is the number and size of this year’s winter kills.

“We are getting dozens of reports of significant winter fish kills from all over the state,” says O’Hearn, “from places with shallow water, such as Eagle Bluffs Conservation Area, and from huge water bodies such as Truman and Table Rock lakes, Lake of the Ozarks, and Pomme de Terre and Stockton reservoirs.”

The abnormal size and number of fish kills is related to abnormally cold weather. Missouri State Climatologist Pat Guinan says the period from Dec. 1 through Feb. 28 was the coldest since the winter of 1978-79 and the ninth-coldest on record.

How cold was it? Guinan says it was cold enough to cause a rare phenomenon known as “frost quakes” in eastern Missouri. These occur when the temperature drops so fast that freezing soil expands rapidly and builds up pressure similar to the pressure in much bigger seismic zones deep in the earth’s crust. Release of this pressure produces popping, cracking noises like the ones people reported hearing on Jan. 26 and Feb. 2.

That same cold dropped the temperature of water and created unusually thick, widespread ice. Conservation Department Fisheries Management Biologist Greg Stoner observed that Lake of the Ozarks was a solid sheet of ice from Bagnell Dam to Truman Dam in January, a rare occurrence.

Then came the snow. Winter storms dumped more than a foot of snow overnight in parts of Missouri. O’Hearn and Stoner say that can be a lethal combination.

“Deep snow can prevent light from reaching aquatic plants,” says O’Hearn. “Without light, plants begin to die, and when they die, they not only are not releasing oxygen into the water, their decomposition actually consumes oxygen. If that goes on for long enough, like it has this year, fish can suffocate.”

O’Hearn says low-oxygen winter kills are fairly common in small, shallow ponds, but this year’s unusual conditions caused them to happen even in large lakes.

Stoner says that temperature alone can cause winter kills. Fish normally go into winter with enough fat reserves to survive. But colder-than-normal water can exhaust those reserves. Small fish are most vulnerable to cold stress, and that is part of the reason Lake of the Ozarks suffered a large-scale die-off of shad.

“We knew going into the fall that we had a very strong year-class of shad produced in the spring of 2013,” says Stoner. “When yearling shad are that abundant, they are generally smaller than average going into the winter, and with less fat reserves. Follow that up with a hard winter, and the result can be widespread die-offs of shad, especially the yearlings.”

As bad as die-offs may seem, Stoner says they seldom have a serious effect on fish populations as a whole.

“Shad can live eight years or longer,” Stoner says, “so losing a significant portion of one year-class still leaves plenty of adults to spawn this spring. If there is any impact on the game fish in the lake, it will likely be a temporary shortage of food this spring and a reduction in the rate of growth for game fish still too small to eat anything bigger than the smallest shad.”

Stoner says the impact of winter kills on fishing prospects are harder to predict on smaller bodies of water. The outcome depends on water depth, duration of snow cover, and fish population size. Ponds with prolonged snow cover sometimes experience total kills and require restocking.

Stoner and O’Hearn urge people who see fish kills to report them to the nearest Conservation Department office. Such reports help MDC evaluate the extent and severity of losses. It is always possible that a particular fish kill resulted from pollution or some problem other than winter conditions. If pollution is suspected to be killing fish or wildlife, call the Missouri Department of Natural Resources Environmental Emergency Response Line at 573-634-2436.

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MDC offers bright side for drought-lowered fishing ponds

 (Photo credit: gval.net)

By Bill Graham, MDC

KANSAS CITY, Mo -- There are some upsides to this summer’s withering heat and drought conditions that have lowered pond and lake levels. In ponds with deep enough water for fish to survive, the big fish are eating well. For pond owners, low water offers a good time to make improvements in ponds that can help in future drought.

Some ponds receive too little fishing pressure, said Scott Ryan, MDC Fisheries regional supervisor for Northwest Missouri. That can lead to stunted growth in bass and bluegill. Plus, vegetative growth can get heavy near pond banks and keep prey fish hidden.

But when water levels drop below vegetative lines, prey fish are forced into deeper water with the predators like largemouth bass.

“This allows the stunted largemouth bass the opportunity to grow significantly with the newly available food source,” Ryan said, “and by thinning the number of bluegill, the surviving bluegill have more food so they too will tend to grow to a larger size.”

The setback for vegetation can also provide a few years with less growth and improved fishing conditions for anglers.

“One of the biggest problems landowners report with their ponds is excessive vegetation,” he said. “If water levels stay low over the winter, a significant portion of emergent vegetation will be exposed to winter freezes and will not survive into next year. Droughts can improve the overall conditions in many ponds.”

Shallow depths and hot temperatures can cause low oxygen levels in pond water, which can cause fish kills. A partial fish kill in a pond with an overabundance of fish can thin out the weaker fish and allow survivors to grow larger in coming years, Ryan said.

Major fish kills are not good. Some have been reported in shallow ponds this summer. The best prevention for summer fish kills is to construct ponds properly or deepen them if siltation occurs, said Jake Allman, MDC Fisheries biologist in the Kansas City region. Ponds that have water depths eight feet or greater over at least 25 percent of the pond’s acreage are much more likely to keep fish alive during these hot and dry conditions.

If your pond does have a fish kill, it may be time to deepen it and make it more hospitable for fish in extreme weather, Allman said.

Good rains, full ponds and healthy aquatic ecosystems make for happy fishing outings. But even in this summer of extreme drought, the fish in many ponds will survive and thrive in seasons ahead.

For more information, visit MDC online at mdc.mo.gov/landwater-care/lake-and-pond-management.