Pond and fish management important during summer months

• Writer: Adam Russell, 903-834-6191, adam.russell@ag.tamu.edu
• Contact: Dr. Billy Higginbotham, 903-834-6191, billy.higginbotham@ag.tamu.edu

OVERTON – Texas pond owners can improve and protect their recreational opportunities with vegetation and fish population management during the summer months, said a Texas A&M AgriLife Extension Service specialist.

As temperatures increase and summer nears, recreational activities on Texas farm and ranch ponds will increase, said Dr. Billy Higginbotham, AgriLife Extension wildlife and fisheries specialist, Overton.

The 1 million-plus private impoundments in the state can provide exceptional fishing opportunities, provided landowners employ proper management techniques to control aquatic vegetation, manage fish populations and protect them from oxygen depletion in the upcoming months, Higginbotham said.

Aquatic vegetation growth is the No. 1 problem that plagues Texas pond owners during the growing season, he said. Excessive vegetation can hamper recreational activities, such as fishing and swimming, and in some cases negatively impact livestock watering and irrigation uses of the pond.

“Just because some aquatic vegetation is present, it doesn’t necessarily mean control is required,” Higginbotham said. “In fact, ponds managed primarily for largemouth bass may benefit from some aquatic vegetation as it provides both habitat and harbors a variety of food sources. But, once weed coverage exceeds about one-third of a pond’s surface, the benefits provided begin to decline as too much vegetation may limit the ability of bass to access forage fish present.”

The first step for successfully controlling aquatic vegetation is proper species identification, Higginbotham said. Samples can be submitted to AgriLife Extension county agents or a fisheries biologist for assistance with identification.

AgriLife Extension’s aquatic weed website, http://aquaplant.tamu.edu, is another excellent resource for aquatic weed identification purposes, Higginbotham said. The Aquaplant website also provides species-specific control recommendations, including chemical, biological and mechanical options.

“Once summer arrives and water temperatures increase, pond owners should conduct chemical weed control activities with special care if fish are important,” he said. “Killing too much vegetation at once can result in decaying matter reducing the oxygen content available for fish and can result in oxygen depletion that could result in fish losses. This is particularly true if algae or submerged moss species are targeted for control.”

OXYGEN DEPLETION

Pond owners should also be aware that the warmer water temperatures during summer decreases the ability of water to hold oxygen, Higginbotham said. High temperatures set the stage for oxygen depletions, which are possible even if weed control activities are not conducted.

Raising catfish in farm ponds and practicing a regular supplemental feeding program can easily produce 1,000 pounds of edible-size catfish per surface acre of water for pond owners on an annual basis, Higginbotham said. However, if the fish crop is allowed to exceed this level during the summer, the pond is more likely to suffer from an oxygen depletion due to the total weight of fish present.

“Ponds at or above the 1,000 pound per acre-threshold should have a significant portion of the fish crop removed to accommodate expected fish growth during the growing season,” he said. “In catfish ponds, seining, trotlining and the use of fish traps and hoop nets are all good methods to reduce large fish standing crops in a short period of time.”

Weather conditions also contribute to pond oxygen depletion, he said. Several hot, still cloudy days in a row limits oxygen production in the pond via photosynthesis. As a result, oxygen levels can decline to the point that fish losses occur.

Additional weather events can also trigger an oxygen depletion due to pond turnover, Higginbotham said.

“During the summer months, many deep ponds develop water stratification, where a warmer, lighter layer of water is found above a cooler, denser layer of water,” he said. “A cold thunderstorm or wind can cool the oxygen-rich upper layer of water to the same temperature of the oxygen-deficient deeper water and the result is a mixing of the two layers. Organic matter on the pond bottom is stirred into the water column and undergoes further decomposition while the overall oxygen content of the water declines to the point that fish die within a day or two of this weather event.”

Pond owners can watch for several signs of oxygen depletion, Higginbotham said.

If fish are being fed regularly, a sudden lack of fish response to feeding may indicate low oxygen, he said. In addition, a sudden water color change from light green or clearer to brown or black may indicate a phytoplankton die-off and rapid decline in oxygen content.

“Oxygen will be at its daily low at daylight, so pond owners should also check their ponds early in the morning if low oxygen is suspected,” he said. “Numerous fish swimming lethargically at the surface at or near daylight is another sign of low oxygen content. Large fish are often the first fish that show signs of distress when an oxygen depletion occurs.”

Should an oxygen depletion occur and fish are an important resource to the landowner, quick action can mean the difference between a pond full of dead fish or a pond full of fishing opportunities, Higginbotham said.

Running a boat with an outboard motor in a fixed position, either against the bank or on a trailer backed into the water can help circulate the water and increase its oxygen content, he said. If a boat and motor are not available, a pump set where the intake pulls water from near the surface and sprays it back over the pond can also increase oxygen by establishing a temporary circulation pattern and bringing more water in contact with the air interface at the surface.

“The summer months provide great recreational opportunities involving Texas farm and ranch ponds,” Higginbotham said. “Diligent weed control and a keen eye on the water can guarantee sustainable fishing and healthy fish populations throughout our long hot Texas summers, and beyond.”