No Carping Without a Permit

Please note the publication date of this article. Statistics and seasonal information were accurate at the time of publication. Check links provided for the most current information.

By Larry D. Hodge

Published in Texas Wildlife, March 2005

Aquatic vegetation can be one element in a healthy fishery. Plants provide habitat for fish and add oxygen to the water. However, it’s possible to have too much of a good thing. Excessive aquatic vegetation can make fishing, boating and swimming difficult or almost impossible.

Using grass carp to control nuisance vegetation in ponds is an attractive idea. The fish work for free (after the initial investment to purchase the fish), no chemicals are required and no expensive machinery is needed. Compared to alternative methods of control, grass carp are very inexpensive. But grass carp aren’t the answer to every situation, and if they are mismanaged can cause damage that is very expensive to repair. Like most simple answers to complex questions, there’s more to introducing grass carp than meets the eye.

Meet the Carp

Grass carp, also known as white amur, are native to the Amur River in eastern Siberia. They are related to the more familiar (and undesirable) European carp but share few of its habits. Grass carp feed only on plants and will not intentionally eat fish eggs or young fish. They live for at least 10 years and may grow to 60 pounds or more. Grass carp were introduced into the United States in 1963 by the U.S. Fish and Wildlife Service for experimental purposes. Texas has allowed stocking of triploid grass carp since 1992. (Read about the Texas program)

Like most exotics, grass carp can become very destructive when introduced into an ecosystem that has no natural controls for them. Therefore, Texas Parks and Wildlife Department (TPWD) requires water body owners—public or private—to obtain a permit before stocking carp. In addition, only triploid grass carp may be stocked. Triploid grass carp are sterile and cannot reproduce. However, they are long-lived, and if they escape, they can do considerable damage.

The impact of grass carp on a body of water should be considered carefully with regard to overall management objectives. "Lots of respected and successful pond managers in Texas and throughout the Southeastern U.S. manage ponds for no vegetation," says Ken Kurzawski, regulations director for TPWD's Inland Fisheries Division. "Plants tie up available nutrients; they don’t add nutrients to the water. That’s why some pond mangers try to eliminate plants. They want all available nutrients going to primary productivity (phytoplankton) and up the food chain to fish. In their view, any plants are just wasted and unavailable nutrients." On the other hand, many of the plants grass carp prefer to eat are also important for waterfowl food, so if both bass fishing and duck hunting are part of your operation, grass carp can be a double-edged sword.

Will Triploid Grass Carp Work for You?

If your nuisance vegetation consists mainly of plants carp prefer to eat, such as bushy pondweed, American pondweed or hydrilla, grass carp may be an option. (To find out what kinds of plants are growing in your pond, contact your county extension agent or visit the online Pond Manager Diagnostics Tool.)

Another factor to consider is the possibility of escape. Triploid grass carp seek flowing water and will go on the lam if not contained. If carp escaping from your pond can possibly reach public water, you will be required to install an escapement barrier across your spillway or overflow pipe that meets minimum standards set by TPWD. In brief, the barrier should consist of steel bars spaced two inches apart and should extend at least two feet above the normal high water level, since carp are excellent jumpers. (Learn more about how to build a barrier.) If preventing escape is not possible, chemical or mechanical control are better options.

Grass carp pose special danger to areas harboring threatened, endangered or unique species and to coastal marsh habitat. As a result, applications for triploid grass carp permits from the following counties run an increased risk of denial: Aransas, Brazoria, Brewster, Caldwell, Calhoun, Cameron, Chambers, Comal, Crane, Crockett, Culberson, Galveston, Gonzales, Harris, Hays, Jackson, Jeff Davis, Jefferson, Kenedy, Kleberg, Loving, Matagorda, Menard, Nueces, Orange, Pecos, Presidio, Reeves, Refugio, San Patricio, Terrell, Val Verde, Victoria, Ward and Willacy. If your property is in one of the above counties, it would be a good idea to contact the Inland Fisheries permit coordinator at (512) 389-4444 before submitting an application.

Know the size of your pond, the extent of plant coverage and how long you are willing to wait to see results. The recommended stocking rate for triploid grass carp is five per acre if plant coverage is 50 percent or less, and 10 per acre if more. To get the greatest benefit and quickest results, it helps to pre-treat the pond with herbicide or draw the water down to promote winter die-off of plants before stocking in the spring. Even then it may take several years to achieve control.

You should also be willing to undertake long-term monitoring. If too few carp are stocked, plants they don’t prefer to eat may become overabundant. If you wish to maintain some vegetation in the pond and too many carp are stocked, they may eat every plant in the pond. Since carp are hard to catch by fishing, it may be difficult to remove them. Even if all goes well, you may have to restock the pond with carp every five to seven years.

Using triploid grass carp for vegetation control is like a poster you may have seen: “You want it good, fast and cheap? Pick two.”

Still Want a Permit?

To legally purchase and stock triploid grass carp, you must obtain a permit from the Inland Fisheries Division of TPWD. You may request an application by mail by calling (512) 389-4444 or download one from the website. The cost is minimal—$15 plus $2 per fish requested. (You must also purchase the fish from a source approved by TPWD; you’ll be sent a list when your application is approved.) Approval of the permit may require an on-site visit by TPWD personnel and will take at least four to five weeks. Any additional purchases of fish will require a new permit.

Ranchers are familiar with the old expression, “It’s too late to close the barn door after the horse is gone.” Every responsible rancher is careful about what livestock he or she brings onto the land, guards against overgrazing and takes measures to keep animals where they belong. The finned “livestock” in ponds deserve no less care.

Additional information:

Our aquatic vegetation pages summarize the problem of nuisance vegetation in our waterways and discuss various management techniques.

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