Weed Control and Wildlife Enhancement is part seven of seven in the Management of Recreational Fish Ponds series.
Aquatic weeds are a common problem in farm ponds. Some aquatic vegetation might be good for the pond. Rooted aquatic vegetation does provide habitat for some small aquatic animals, which add to the food chain. Vegetation also provides small fish with places to hide from larger predators. The problem with weeds is uncontrolled growth. If too many weeds become established in the pond, too many small fish survive (that is, over-populate), and removal of nutrients by the weeds reduces algae production (food). Also, predators become thin because they are not able to prey on the forage species.
Aquatic weeds can be controlled by manual, chemical, and biological means. Manual control of species like cattails is practical when they first start to colonize a pond. Woody vegetation along the dam also can be controlled manually.
Chemical control with herbicides is possible, but few herbicides are approved for aquatic use, and the type of aquatic vegetation must be accurately identified before it is treated. Some herbicide applications can kill planktonic algae, leading to oxygen depletion. Oxygen depletions after herbicide treatment are particularly common in hot weather or if the pond is heavily infested with weeds. Check with a fisheries biologist or the county Extension office for plant identification and current herbicide recommendations. When using chemical pesticides, protect yourself and others by strictly following all label directions.
The simplest and most economic long-term aquatic weed control method is to stock grass carp. The grass carp, or white amur, is an Asian carp brought to this country for aquatic weed control. Grass carp consume vegetation almost exclusively after they reach 10 inches in length. They will not reproduce in the pond, will not muddy the pond like common carp, will not disturb the nests of other fish, and they will consume 30 to 40 percent of their body weight in weeds every day during warm weather.
Grass carp are attracted to running water and will leave the pond over the emergency spillway during heavy rains. Prevent escape by building a correctly designed barrier across the spillway. A list of where to purchase grass carp and information on how to build an escapement barrier can be obtained from your county Extension office.
The number of grass carp that should be stocked depends on the type of weed, condition of the pond, and magnitude of the weed problem. For new ponds or ponds with no significant weed problems stock 3-5 grass carp per acre as a preventative. If the pond has a moderate weed problem, stock 10-15 per acre. Ponds with severe weeds or weeds that are difficult to control may require 15-20 or more grass carp per acre. If stocking grass carp into a pond with mature bass, stock an 8-inch or longer (10- to 12-inch) fish. Grass carp are less effective at controlling weeds after they reach 20 to 30 pounds in size (usually 5 to 7 years after stocking). As vegetation starts to reappear, restock the pond with new grass carp. While large grass carp do not have to be removed, they can be harvested by angling with a light wire hook baited with a small dough ball (bread works well) or by bow-fishing. Grass carp are excellent table fare.
In the case of a severe weed problem, it may be practical to treat the pond with a herbicide first and then to stock 10 to 15 grass carp per acre to maintain weed control. Contact your county Extension office for information on chemical control of aquatic weeds.
Alternative Stocking Strategies
Ponds of less than 1/2 acre are very difficult to manage for bass-bream. Probably the best management strategy for this size pond is to stock it with channel catfish only. Catfish are splendid fighters and are great to eat. The best way to calculate how many to stock is to figure that it will cost you about 50¢ per pound to get them to eating size. This may take from 1 to 2 years, depending on how often and how well you feed them. Stock 300 to 2,000 catfish per acre and feed them April through October and at reduced rates during the winter. Feed no more than 6 days per week and do not feed more than 20 pounds per acre per day (table 6).
Table 6. Approximate Feeding Rates from April through November for Catfish-only Ponds on a 6-Day Per Week Feeding Schedule
|Month||Water Temperature (Degrees F)||Approximate % Body Weight/Day (300 fish/acre)||Approximate % Body Weight/Day (800 fish/acre)||Weight of Feed Per Acre (300 fish/acre/lb/day)||Weight of Feed Per Acre (800 fish/acre/lb/day)|
|April||60 to 70||2||2||6||16|
|May||70 to 80||2.3||2.3||6.9||18.4|
|June||80 to 85||2.5||2.4||7.5||19.2|
|July||83 to 86||2.8||2.5||8.4||20|
|August||83 to 86||3||2.5||9||20|
|September||75 to 85||2.5||2.4||7.5||19.2|
|October||65 to 75||2||2||6||16|
Table 6 assumes that the average weight of the fish is about 1 pound. In this kind of management system, fish removed by fishing can be replaced by restocking 5- to 6-inch catfish fingerlings in the early spring. For a winter feeding schedule, contact your county Extension office.
Catfish in many cases will reproduce too much if stocked alone in ponds. Bass can be stocked at about 20 to 30 per acre with catfish to limit reproduction. Another way to limit overpopulation is to stop reproduction. Since catfish are cavity spawners, reproduction can be limited in ponds by (1) removing all stumps, rock piles, etc.; (2) not allowing muskrat or beavers to colonize (catfish will spawn in the burrows); and (3) not providing any type of container that could be used for spawning (for example, tires or barrels).
Other fish that can be stocked in small ponds include blue catfish, hybrid bluegill, threadfin shad, golden shiners, fathead minnows, and rainbow trout. Before stocking these species, talk with a fisheries biologist.
Blue catfish can be stocked instead of channel catfish. They grow larger and are better predators than channel catfish, but they will compete with bass.
Hybrid bluegill have a large mouth and train readily to commercial fish feed. They will grow rapidly if fed commercial fish feeds and are excellent for angling. Hybrid bluegill, however, are not sterile as is sometimes claimed. Most are males but if females are present they will reproduce. Offspring produced are undesirable; therefore, hybrid blue-gill should be stocked with 20 to 30 bass per acre to prey on any young produced. Every 3 to 4 years the pond will need to be drained and restocked.
Golden shiners, fathead minnows, and threadfin shad can be stocked for forage. Many states promote the use of golden shiners or threadfin shad as bass forage. Both species can reproduce rapidly in ponds and provide excellent forage for bass. Golden shiners will compete with young bream for food, eat bass and bream eggs, and can overpopulate if there is a significant amount of vegetation or brushy structure in the pond. Threadfin shad are excellent bass forage but may not survive winter temperatures in some parts of Alabama. Fathead minnows are slow swimmers and do not grow large as adults. If ponds are stocked with bass, fatheads are quickly eliminated (see Turn-Overs and Enhancement Strategies). In small ponds stocked with only channel catfish and not fed regularly, fathead minnows can provide excellent forage. Stock about 500 fathead minnows per acre.
Rainbow trout will survive only during the winter in Alabama ponds. Rainbow trout can be stocked when water temperature is near 65 º F, usually by early November. Rainbow trout, stocked as 7- to 9-inch fingerlings, will grow rapidly feeding on insect larvae and small bream. Rainbows will also take commercial fish feeds and can grow to 1 pound by April. Rainbows will die as water temperature reaches 70 º to 72 º F in early April. Trout angling can be outstanding when water temperature is above 50 º F in March and early April.
Many of the basic problems of farm pond management have already been discussed. These included how to maintain a good food supply for the fish, how to harvest to maintain a balanced population, how to check balance, how to control weeds, and how to avoid fish kills from algae bloom die-offs. These are not simple problems. Ponds are complex systems that take understanding and commitment to manage properly.
One common problem in Alabama is pond “turn-over.” Turn-overs naturally occur when ponds cool in the fall, but fall turn-overs are seldom a problem. Problem turn-overs occur during warm weather when ponds are stratified: surface water is warmer than the water below and the two layers no longer mix. This causes the cooler water near the bottom to stagnate and become depleted in oxygen. Fish avoid this layer of water. A turn-over occurs when the warm upper layer suddenly cools and mixes with the stagnant layer. The two layers mixed together may not have enough oxygen to support fish and they die. This usually occurs after a cold, hard rain. If a turn-over occurs, quick aeration may save the fish. Similar fish kills can also be caused by oxygen depletions from a bloom die-off or rotting vegetation from herbicide treatment.
Many techniques can be used to enhance fishing in ponds. Some of these include stocking of fathead minnow forage, construction of fish shelters, supplemental feeding, manipulating water level, aeration, and destratification.
Fathead minnows stocked at about 500 per acre the first year of a new or renovated pond will improve bass survival and growth. Fatheads should be stocked in February or March before the bass are stocked in June. Fatheads will spawn and produce abundant forage for the young of year bass. Bass will eliminate the fatheads within a few months and turn to bream for forage.
Fish shelters or “attractors” can be made from many different materials (See figure 2). The purpose of a fish shelter is to provide a place for some small fish to escape predation and attract fish for anglers. These structures should be at a depth of 2 to 6 feet. Discarded Christmas trees and cedar trees make excellent shelters if anchored to the bottom. Stake beds (stakes driven into the bottom), rock piles, and tire reefs are also good shelters. Usually only one reef is placed for every 1 to 3 acres and no more than three per acre.
Supplemental feeding of commercial fish feeds increases bream and catfish growth. Bass do not readily consume artificial feeds but benefit from the increase in bream reproduction. Feeding can possibly double the average size of harvestable fish and total pond production (up to 600+ pounds per acre). Fish can be fed throughout the warm months of the year, but best results are obtained by feeding from March through May and October through November when most bream growth occurs. Feed three or four times per day. Feed in the same area and at about the same time of day. Feeding can be done by hand or with demand or automatic feeders. Floating feeding rings for containing the feed can be made from PVC tubing anchored in place. Provide one feeding station for each 3 acres of pond.
The protein level of the feed is not very important. Studies have shown that low protein (25 percent) will produce excellent growth. Therefore, it is not necessary to purchase high protein feed.
It is very important not to overfeed. Feed all the fish will eat in 10 to 15 minutes, but not more than 10 pounds per acre per day. Winter feeding is not necessary but may promote increased bluegill growth. In winter feed sinking pellets at a rate not to exceed 3 pounds per acre per day.
Feeding is expensive but can be effective in attracting bream and catfish making them easier to catch and increasing their growth. Feeding can stimulate plankton blooms similar to fertilization because of the nutrients in the feed. Make sure to use a Secchi disk to measure water clarity before adding fertilizer especially when also supplemental feeding.
Ponds with drains have distinctive management advantages. Water level can be drawn down several feet (2 to 3) in late fall through mid-winter. This action helps control aquatic weeds by exposing them to drying and freezing. Draw-downs also concentrate the fish, making forage fish more available to the bass. This practice increases bass growth and reduces bream overpopulation. Caution: Drain valves must be well maintained or they may not open and close properly. The pond should be allowed to refill in February and March.
Ponds that have a history of fish kills will benefit from aeration or destratification (if deeper than 8 feet), or both. Many types of electric aerators are available commercially. Supplemental aeration requires approximately 1/2 to 1 horsepower of aeration per surface acre of pond. If a turn-over or bloom die-off occurs, additional aeration may be necessary.
Thermal layering (stratification) can be stopped by using blowers, underwater fans, and propeller aspirator type aerators. Destratification will eliminate the chance of a fish kill caused by a turn-over and increase the area of the pond inhabited by the fish during the summer months. However, destratification does alter algae blooms and may increase low oxygen problems during periods of overcast weather. For additional information on aeration and destratification devices contact your county Extension office or fisheries specialist.
Fish also can be encouraged to spawn where you want them to by providing them with a good spawning substrate. Place sand and gravel beds in several locations around the shoreline in 2 to 5 feet of water. The sand and gravel should be 4 to 6 inches deep and can be contained in a frame or box if the bottom is particularly silty. These beds allow the pond owner to concentrate seining efforts in areas where spawning should have occurred.
Wildlife, both game and non-game, require food, water, and shelter to survive. If managed properly, ponds can provide fishing while, at the same time, providing food and shelter for a variety of wildlife species. The illustration at the right depicts how the upper reaches of a pond can be managed for wildlife, while the lower areas adjacent to the dam have the characteristics of a typical fish pond. Not more than approximately half of the pond area should have water less than 2 feet deep. Ideally, the pond should be constructed so that the upper reaches of the pond can be dried by draining during May through October. The dewatering exposes an area of mudflats. In the mudflats natural vegetation may grow or specific plants can be planted. These mudflats are then flooded in the fall and provide habitat and a food source for ducks and other waterfowl. Draining and flooding can be accomplished by fitting the standpipe with two valves, one to drain the pond completely and the other positioned to dewater only the upper reaches of the pond. Nesting boxes placed in the pond can provide artificial nesting cavities for wood ducks. For more information on wood ducks, contact your county Extension office.
Ponds serve as watering sites for a variety of wildlife species. Ponds with cleared and sodded shorelines (15- to 20-feet wide) provide an unobstructed view of the pond and are excellent watering sites for mourning doves and other bird species. However, using this area to plant native trees and shrubs with persistent seeds and fruits will provide food for a variety of wildlife and encourage their frequent use of the pond.
Wading birds, aquatic reptiles, and amphibians are a natural part of any pond. These animals can provide many hours of enjoyment to those who have the opportunity to watch them.
Whether it is waterfowl to be hunted or non-game species to be watched, wildlife can enhance the recreational benefits of ponds. Contact your county Extension office for more information on maximizing wildlife around a pond.
Ponds serve as watering sites for a variety of wildlife species. Ponds with cleared and sodded shorelines (15- to 20-feet wide) provide an unobstructed view of the pond and are excellent watering sites for mourning doves and other bird species. However, using this area to plant native trees and shrubs (although not on the dam!) with persistent seeds and fruits will provide food for a variety of wildlife and encourage their frequent use of the pond. Incorporating legumes such as clover in the ground cover and areas of wildflowers in areas that won’t be mowed will attract and support pollinators like honey bees.
Small farm ponds are not Mother Nature’s creations; they are the work of human beings. They must be managed to be productive and provide good fishing. Again, think of a pond as you would a garden or orchard. It must be properly laid out, perhaps fertilized, planted (stocked), weeded, pruned (in this case, selectively harvested), and protected from climate-related catastrophe (for examples, turn-overs) to be bountiful. All of this takes time and effort, but the rewards are outdoor recreation and good food.
All fishing should be recorded. Provide number of fish caught. If no fish caught, place zero under species fished for (record time spent in hours; one person initial in case more information is needed).
Management of Recreational Fish Ponds Series