All responsible lake managers are tasked with the duties of managing lakes and storm water ponds in a manner that is both cost-effective and beneficial for the client. In addition, the management of the lakes and storm water ponds needs to be environmentally friendly to meet eco-system specifications. To meet these requirements, it is necessary to implement different multi-faceted strategies utilizing beneficial tools to get the job done. Ecological balance is rarely obtained using a single methodology, and without balance there are rarely positive results.
A biological control refers to the utilization of natural methods to achieve a desired management objective in a body of water. The triploid grass carp is often used by lake owners and managers to assist in controlling unwanted aquatic vegetation. It seems odd to use a fish as a form of waste management, but the grass carp’s ferocious appetite for plants growing in or around a lake is useful to remove the unwanted organic items.
To own and utilize this type of fish, it is necessary to hold a permit before placing them in the pond or lake. The fish is regulated by the Department of Game and Inland Fisheries where managers are able to obtain the permits. It is also required for the carp to be sterile so that they do not over produce and cause harm to the lake or pond by over-eating the plants.
As environmental agents, lake managements tend to avoid the introduction of plants or fish that are not native to the area as this will upset the eco-system. This type of carp, however, is highly beneficial despite not being native to North America. It is important that they be used carefully as a management tool if they are chosen. The need to sterilize the fish when they are grown is a positive technique, but there are additional measures that need to be considered.
One of the first considerations is to not overstock the lake or pond with the carp. Approximately 20%-30% coverage of the wetland plants is needed for the pond to be deemed a healthy and balanced area. If the carp is used to control unwanted plants, it is recommended that there is enough stock to eat a particular quantity of plants per day, but not enough to eliminate all the plants inhabiting the pond.
It is also recommended that a screening structure be installed in front of any outflow devices evident in the pond or lake. If the pond presents with an outflow device, it would allow the carp to escape during a heavy water flow. By installing a screening structure, it is possible to prevent the fish from swimming downstream leading to a saving of money.
Finally, the grass carp is primarily a bottom feeder and as such as a tendency to stir up the sediment on the pond bottom. In shallow ponds, this results in an excessive amount of dirty water. Ultimately, even if all the unwanted plants are consumed, you may end up with a dirty pond overall and will need to replace the water.