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Tilapia Regulations: Aquatic Vegetation Control

April 16, 2021 by brittany.chesser

Over the past month, there has been a high demand from pond owners in receiving information on pond stocking strategies for their recreational fisheries. This topic was covered in depth during the January 2021 Aquatic Webinar, but another topic along the same vein, is fish stocking for aquatic vegetation management. There have been some recent regulation changes that are worth noting.

Triploid grass carp (Ctenopharyngodon idella) and Mozambique tilapia (Oreochromis mossambicus) are the two herbivorous fish options used for aquatic vegetation management in Texas. While both of these species consume aquatic plants, they each have their own preferences. Mozambique tilapia are most effective at controlling floating plants, primarily duckweed and Azolla and are also known to consume some filamentous algae and watermeal. Control effectiveness and longevity are increased significantly when combined with other management practices like mechanical or chemical control, as an integrated pest management strategy. If stocked into a pond with a large bass population, they will be subjected to predation which will reduce any aquatic vegetation control.

Up until recently, only Mozambique tilapia could be obtained from a Texas Parks & Wildlife Department certified dealer, without a requiring a permit. All other species, including hybrids, were illegal to stock in outdoor ponds.

New regulations, effective January 27, 2021, has broadened the tilapia species legally allowed to stock in outdoor ponds to include, not only Mozambique tilapia, but Blue tilapia (Oreochromis aureus), Nile tilapia (Oreochromis niloticus), and Wami tilapia (Oreochromis urolepis), along with their hybrids. This new ruling is put in place to relieve any concerns regarding misidentification for all parties involved in the process.

Additionally, two management zones have been identified in regards to stocking these tilapia species in Texas– a conservation zone and a stocking zone. These zones are largely split by Interstate Highway 35 and created in response to a conservation assessment weighing both environmental and economic impacts. For tilapia to be stocked in outdoor ponds in the conservation zone (approx. West of I-35) a departmental review will be required, at no cost, to determine if tilapia escapes are likely. This process is not necessary for ponds located in the stocking zone (approx.. East of I-35).

These new stocking zones will also play a role in triploid grass carp permits for private ponds. Landowners with ponds in the stocking zone will have the opportunity to be fast tracked through the permit process when requesting 10 or less carp.

For more information tilapia and triploid grass carp stocking regulations please visit the Texas Parks & Wildlife Department webpage. The full list of counties within each zone and a request for approval to stock tilapia in the conservation zone can be found here.

 

 

Filed Under: Uncategorized

Clearing Up Ponds & Confusion

January 26, 2021 by brittany.chesser

Ponds with a muddy appearance can be an eyesore to some pond owners, which is why one of our most popular tests, behind the basic water chemistry analysis, is the water clearing treatment test. Truly muddy or turbid water loses its transparency due to suspended clay particles. This can be attributed to the presence of bottom dwelling fish like catfish, koi, and carp, along with aerators, livestock wading, erosion, or disturbances caused upstream in the water shed. If the cause for the disturbance of clay particles is not identified and resolved before a clearing treatment is applied, particles will be re-suspended or readily introduced, and treatments will only be temporary.

Additionally, lack of water clarity is not always the result of suspended clay and a crystal clear pond should not be your goal. Serious problems can arise with water clarity over 24” deep, like large aquatic vegetation infestations or inadequate food for fish growth. This is the reason fertilization treatments or pond dyes may be recommended for a pond. Maintaining water clarity between 18-24” limits the amount sunlight reaching the pond bottom, reducing the amount of aquatic plants that are able to establish. It should be noted that recently dug ponds will experience high clay turbidity rates for the first couple of years. Most of these ponds will clear on their own overtime.

A theme you will see throughout our lab is the recommendation of starting with a basic water quality analysis, and pond clearing is no exception. When thinking of pond clearing agents, most think of calcium carbonate, also known as agricultural lime. However, there are three other basic chemicals plus synthetic polymers that can be used to clear ponds with fish in them. If fish are not present, there are six possible treatments. Water chemistry within a pond influences interactions among all these chemicals and will help determine which chemicals will produce the best result and help determine how much chemical is necessary to achieve a clearing result. Two specific parameters we examine are alkalinity and hardness concentrations. The ratio between alkalinity and hardness and whether they are at sufficient concentrations, over 50 parts per million, is a good indicator on which chemicals will be the most successful at clearing a pond. Many clearing treatments will shift pH and could be dangerous to fish if sufficient buffering is not present, so anticipated changes in pH will also be considered when recommending a treatment.

Clearing treatment effects vary from pond to pond and may last 1 day or 5 years. Some ponds may never clear to desired standards regardless of treatment type or application, due to other soil and environmental influences.

Water samples in need of a basic analysis and clearing treatment test can be sent to The Texas A&M AgriLife Extension Service Aquatic Diagnostic Laboratory. Due to the amount of water needed for a clearing test, a minimum of 1.5 gallons is required. For more information and instructions on how to perform your own clearing test, please read Clearing Muddy Ponds.

Filed Under: Uncategorized

Saprolegniasis

January 24, 2020 by brittany.chesser

Saprolegniasis, also known as winter fungus, is a disease caused by fungi usually in the genus Saprolegnia. Found in freshwater fish and fish eggs, saprolegniasis is a secondary infection typically seen when water temperatures dip below 59°F and then begin to increase in the early spring. A fish suffering from saprolegniasis will exhibit cotton-like growths on the skin and gills, depigmented skin, and sunken eyes. In more severe cases, the cotton-like growths can extend into the muscle tissue. Infected fish will begin to die slowly over time.

During months where rapid change in water temperature is common, extra measures should be taken to prevent or detect saprolegniasis, so now would be the time to take precautions! Saprolegniasis can be prevented by avoiding rough handling, crowded stocking conditions, and poor water quality. To prevent further spread and reduce overall mortality, fish should be harvested as soon as saprolegniasis is observed.

If caught when the infection is superficial, fish can still be harvested and marketed. Infected fish can be sent to The Texas AgriLife Extension Service Aquatic Diagnostic Laboratory for a microscopic exam to identify and recommend treatment for fungal diseases.
For pictures and more information on saprolegniasis, please read Saprolegniasis and Branchiomycosis of Commercially Cultured Channel Catfish.

Filed Under: Uncategorized

December 11, 2013 by todd.sink

Fisheries Specialist map

https://fisheries.tamu.edu/2013/12/11/4327/

Filed Under: Uncategorized

November 25, 2013 by todd.sink

pond 32

https://fisheries.tamu.edu/2013/11/25/3768/

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November 25, 2013 by todd.sink

pond 31

https://fisheries.tamu.edu/2013/11/25/3765/

Filed Under: Uncategorized

November 25, 2013 by todd.sink

pond 30

https://fisheries.tamu.edu/2013/11/25/3760/

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November 25, 2013 by todd.sink

pond 25

https://fisheries.tamu.edu/2013/11/25/3756/

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November 25, 2013 by todd.sink

pond 22

https://fisheries.tamu.edu/2013/11/25/3754/

Filed Under: Uncategorized

November 25, 2013 by todd.sink

pond 22

https://fisheries.tamu.edu/2013/11/25/3751/

Filed Under: Uncategorized

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