Evaluation of Pond Balance is part six of seven in the Management of Recreational Fish Ponds series.
Managers should conduct an evaluation of bond balance every 1 to 2 years if fishing quality is unsatisfactory. District fisheries biologists with the Alabama Department of Conservation and Natural Resources, Division of Wildlife and Freshwater Fisheries may be able to assist you in checking pond balance. The checks are done beginning in the last part of May and through June. To request a pond check, call the district fisheries office before the end of April. Private fisheries consultants are also available to evaluate pond balance. For a list of fisheries consultants in Alabama, contact your county Extension office.
Pond balance can be checked by using a 15-foot minnow seine (1/4-inch mesh). The best time to check is early June. Seine several (a minimum of three) shallow areas of the pond that are clear of brush and weeds. Allow the seine to arch or cup slightly as it is pulled, so that fish cannot easily swim around it. Samples from seining provide information on reproductive success and presence of unwanted species.
Sampling with a 30-foot or larger (1/2- to 1-inch mesh) seine will provide further meaningful data to evaluate pond balance. Seine one or two areas in the pond. Record the number of bluegill captured in groups: less than 3 inches; 3 to 5 inches; and greater than 5 inches. Pond balance can be evaluated from catch records and seine data or from electrofishing surveys.
Refer to table 5 to analyze pond balance from seine and catch data.
Table 5. Evaluation of Pond Balance Using 15-Foot Seine and Catch Data
|Type of Fish Caught||Concluson||Recommendation|
|Seine data--small and intermediate bluegill and young of year largemouth bass||fish populations in balance||no additional management necessary|
|Angler catch data--bass and bluegill of various sizes|
|Seine data--many intermediate bluegill and few or no young of the year bass||bluegill-crowded||remove intermediate bluegill by shore line rotenone in fall or stock 20-30 adult bass (12_ or larger) per acre|
|Angler catch data--few harvestable size bluegill; few large bass|
|Seine data--few intermediate bluegill; many recently hatched bluegill||bass-crowded||remove 50-75 (35 lbs.) bass per acre|
|Angler catch data--bass, numerous but small and thin; bluegill, few, but large and robust||stock 200, 4-5_ bluegill per acre|
|Seine data--unwanted species, no recent bluegill hatch, few intermediate bluegill||fish populations dominated by unwanted species||retenone and start over|
|Angler catch data--few harvestable size bluegill and unwanted species (crappie, bullhead, green sunfish, shiners, etc.)|
If fishing is adequate and seine data show both young bass and recently hatched bluegill fry, the pond is probably in balance. If no young bass and bluegill fry are found but many 3- to 5-inch intermediate-size bluegill are caught, your pond is probably out of balance. If you find undesirable species, it is time to poison and restock. Tadpoles in large numbers indicate that few bass are present.
If an over-population of bream is the problem, trying to fish, trap, or seine enough bream to restore balance may not be practical or possible. A slow growing and stunted bream population can be corrected by applying rotenone along the margins of the pond in the early fall to achieve a partial kill. Apply rotenone when the water temperature drops below 80 º F, so that surviving bream will not reproduce until the following spring. Water temperatures, however, should not be below 70 º F, as the rotenone will remain toxic too long. In this procedure rotenone is applied to the margin of the pond at a distance of approximately 20 to 30 feet from the shore, but not in water deeper than 5 feet. Usually rotenone is applied at mid-day when the sun is shining and applied so the drift is toward the shore.
The rotenone formulation can be diluted and poured into the prop wash of an outboard motor. Be careful to avoid skin contact. The objective is to remove approximately half the bluegills in the pond. A partial application of rotenone can be a tricky procedure; pond owners may want to contact a state fisheries biologist, fisheries specialist, or fisheries consultant for assistance.
Management of Recreational Fish Ponds Series