As Mid-South water shortages and irrigation needs mount, reservoirs increasingly dot the landscape. And with the reservoirs come new business and recreational opportunities.
Arkansas producers are calling Wes Neal for help with reservoir set-up and management concerns.
“I'm trying to find a way to manage for the differences between regular farm ponds and irrigation reservoirs,” says Neal, University of Arkansas at Pine Bluff assistant professor and small impoundment management specialist. “We want farmers to be able to get multiple uses out of the reservoirs. There's a lot of opportunity beyond irrigation — fee fisheries and short- and long-term leased fisheries are among them. For example, many people are willing to lease 80-acre reservoirs, either annually or daily, that are managed properly for bass.
“If someone has to construct a reservoir because groundwater is becoming scarce, they want to get the most out of their buck. Reservoirs can be a sideline moneymaker through duck hunting, bass or crappie fishing.”
When a reservoir is managed correctly, paying customers can be fishing for bass quickly. A fertilized and stocked pond can have 4- and 5-pound bass in three years.
“One catch-and-release operation I work with has had bass for four years,” says Neal, an avid fisherman. “At the beginning of the fourth year, they caught a 9-pound bass. Now, that's uncommon, but it shows the possibilities.”
Before building and stocking a reservoir, farmers should follow recommendations suggested by the Extension Service and Arkansas Game and Fish Commission (see www.uaex.edu/wneal/pond_management/). But Neal says there are three golden rules for keeping a reservoir in balance: (1) build it properly, (2) stock it properly, and (3) fish it properly.
“Unfortunately, most folks fall down in at least one of those areas. They build it wrong — too deep or too shallow — or they stock based on what their neighbor says.”
More than any other mistake, people don't harvest enough fish. Per acre, an unfertilized pond needs about 15 pounds of bass and 40 to 50 pounds of sunfish harvested annually. However, very few adhere to those guidelines, which leads to overpopulation and stunting problems.
The carrying capacity for largemouth bass is, roughly, 50 kilograms per hectare. A pond that's 5 acres, or 2.5 hectares, can support roughly 125 kilos of bass.
Even though most bass operations are catch-and-release, a managed harvest is critical, says Neal. Some operations make the harvest a special benefit for good customers.
“Some folks let their best clients take fish out of the lake. Others have tournaments with a big fry afterwards.”
Whatever approach is used, “if a pond can carry 50 pounds of bass per acre, you can either have 25 two-pound fish or 10 five-pound fish. So you want to harvest the bass back to allow the fish to grow larger.”
One big difference from a pond is the water for irrigation reservoirs is typically pumped from outside. To fill levee-type reservoirs, landowners “usually either pump from a well — and there are certain problems associated from well-pumping, particularly low oxygen — or they're filling reservoirs from a source adjacent to the reservoirs.”
That adjacent source is often a ditch or a bayou. When transferring water to a reservoir, “rough” or “trash” fish (gar, green sunfish, bullhead catfish, yellow bass and others) often hitch a ride and diminish chances for a well-balanced environment.
“We help deal with rough fish populations regularly. The irrigation reservoirs have water pumped in, and suddenly the landowner has a bunch of gar or green sunfish. Those can cause problems with pond balance and sportfish production.”
Normally, post-reservoir construction calls to Neal deal with aquatic weed problems, rough fish populations and “general, pond-balance troubles. Usually, we recommend you stock a predator (largemouth bass) and a prey (bluegill and redear sunfish). You want good reproduction in both so the bluegill produce lots of small fish for the bass to eat. That way neither population gets out of control and they grow well.”
However, “people can over-harvest the bass and end up with bunches of small, stunted sunfish. Or, more common, are people who don't think they should keep any bass. That leads to a pond full of 10-inch bass.”
How best to clean up rough fish?
“If possible, you can always drain the pond and refill. But when draining isn't feasible, rotenone is still the best way to reclaim the pond.”
Depending on the type of fish targeted, the dosage of rotenone — a commonly used chemical in fish eradications — is different. Normally, though, trash fish are more tolerant of rotenone than game fish, necessitating a total pond clean-up.
Neal has been working with a lake managed for quality and trophy bass that provides daily leases. Leases are limited to two boats a day at $75 per boat.
“That's a great opportunity to make money. And by limiting access, it's easier for (the owner) to manage the fishery.”
The operation recently had an outbreak of largemouth bass virus. The disease is “fairly specific to bass and can cause episodes of mortality in the summer. But it's usually a one-time occurrence, and although fish stay infected, fish kills generally don't reoccur. It turned out he didn't lose many fish and the operation has since recovered.”
Then there are cases that require more detective work.
“We were called out to a small pond that was very turbid (muddy). The owner didn't know why it was so turbid and didn't know why his ducks were dying. He had about 150 ducks on a 2-acre pond and 80 had died.
“My first reaction was ‘150 ducks is surely too many. That's got to be the problem.”
But it wasn't. The cause of the turbidity was an extremely large population of yellow bullhead catfish.
“Those were stirring up the bottom. I pulled a seine haul through it once and came up with thousands and thousands of little bullheads. So I thought, ‘maybe the ducks are eating the bullheads and the spines are getting stuck in their throats, causing damage or preventing feeding.’”
But that wasn't the cause either. It turned out the owner had put a large round bale of hay in the pond to help clear the water, a normal practice.
In this case, however, “the hay was decomposing and the ducks were eating it. Basically, they were dying of botulism.”
Weeds and algae
Neal is also queried on weeds and algae.
“I was just helping someone with ‘green cotton ball algae.’ That's a big problem, particularly when nutrients are enriching a pond.”
Much of Arkansas has poultry houses. Ponds downstream from those houses are more likely to develop problems with the green cotton ball algae or duckweed.
“Those are both very tough to control. There are chemicals and products that work on duckweed. But it's expensive — it usually costs about $500 per acre of water to treat a pond.”
Another weed that's becoming more of a problem is alligator weed, an exotic species. With few options to control it, the weed grows extremely thick around the shore “down to where the light penetrates into the water. It gets so thick it's hard to access the pond banks.”
Because it has very woody stems, grass carp, the biological control for many weeds, won't eat alligator weed.
“Many times, weed problems are related to not stocking grass carp when building a pond. Or, there's a nutrient enrichment problem. Or, the pond is very clear allowing light penetration. When that happens the pond doesn't develop phytoplankton blooms to shade out the bottom.”
Neal has yet to find water hyacinth, an invasive exotic plant, in a reservoir. But he expects to because the aquatic plant has already populated central Arkansas waterways.
“It's just a matter of time before it's found in a pond or reservoir … If on small (acreage), it will probably be relatively easy to control. But it's becoming more and more problematic.”
Last year, on the Arkansas River, Neal saw more water hyacinth than he's seen since moving to the state. “I'm hoping some of the cold temperatures this winter killed it off. Actually … I (also) found water lettuce on the Arkansas River last year. That's another exotic that's similar to water hyacinth.”