Have you seen this fish? Invasive Silver and Bighead carp have been found in the Red River and tributaries in Texas. Help stop them from spreading to new water bodies and threatening native fish populations.
Silver Carp
Silver carp (Hypophthalmichthys molitrix) are heavy bodied fish from the family Cyprinidae and can weigh up to 60 pounds. Silver carp can be identified by having a stout, silver body, low-set, slightly downturned eyes, an upturned mouth lacking barbels, and a keel along the belly that runs from the pelvic fins all the way to the throat. They have tiny scales on the body but lack scales on the head. The silver carp looks very similar to another invasive species, the bighead carp (Hypophthalmichthys nobilis), which is grayer in color and has a keel that only extends from the anal fins to pelvic fins. Young silver carp are similar in appearance to shad but can be identified by their low-set eyes located near the top of their heads,and the lack of a long, whip-like segment on the dorsal fin. Silver carp grow to approximately 3 feet in length and can weigh up to nearly 60 pounds. Silver carp are also known and recognizable for their ability to jump several feet out of the water when disturbed by noise from boats, sometimes jumping into boats and injuring boaters.
Ecological Threat: Silver carp are voracious filter feeders that consume up to half their body weight in plankton and detritus. They are able to outcompete native filter feeding fish, larval fish, and native mussels for resources, negatively impacting aquatic food webs and fish populations. .
Biology: Silver carp reach maturity as early as 2 years old in North America and are capable of reproducing until 10 years of age. Temperatures must reach 18o C for silver carp to spawn. Spawning occurs from May to September, when they can be witnessed migrating upstream in groups of 15 to 20 adults. Each female may lay as many as 5 million eggs per year. Eggs require enough river current to transport eggs downstream and a minimum spawning river length of 62 miles for the eggs to survive.
History: Silver carp were first introduced to the United States in 1973 as an import to stock fish farms in Arkansas for control of phytoplankton. Popularity of stocking the silver carp increased by the mid 1970’s with records of six state, federal, and private facilities importing the fish. The silver carp was ideal for phytoplankton control and a food source. By the 1980’s there were occurrences of silver carp in natural waters due to accidental escapes from stocked ponds and aquaculture facilities.
U.S. Habitat: Silver carp are primarily found in large rivers. Their diet consists primarily of phytoplankton, but they are also known to feed on zooplankton, bacteria, and detritus.
Distribution
Native Origin: The silver carp is native to the major drainages in Eastern Asia, Southern Russia, Eastern half of China, and possibly part of Vietnam.
U.S. Present: Occurrences have been documented in AL, AR, AZ, CO, FL, HI, IL, IN, IA, KS, KY, LA, MN, MS, MO, NE, NV, ND, OH, OK, PR, SD, TN, TX, WI
Distribution in Texas: Texas: Silver carp were recently reported from Texas tributaries of the Red River in 2021, but were already known to be present in the waters of the Red River which borders Texas and Oklahoma, where they have been reported as far upstream as the area just below Lake Texoma in 2019.
Management
Management of silver carp in Texas primarily focuses on preventing their spread. It is prohibited to possess, transport, or introduce silver carp in Texas. If a silver carp is caught, it is permitted to immediately release it back into the water body from which it was taken or to keep it provided it is immediately killed or placed on ice upon possession. Silver carp have tasty, white flesh and are excellent for consumption, but filets have numerous bones. To help prevent the spread of silver carp as live bait, regulations prohibit the transport of live nongame fish from the Red River in Texas where silver carp have been found. Juvenile silver carp are difficult to distinguish from other native species of bait fish (i.e. gizzard shad) and can contaminate live bait. If you believe you have caught a silver carp in a new area, please email location and photographs to Texas Parks and Wildlife Department at AquaticInvasives@tpwd.texas.gov.
Bighead Carp
Bighead carp are invasive, large-bodied, fast-growing, highly fecund, voracious-feeding fish that are rapidly colonizing North American waterways. Notorious for their ability to jump out of the water, they are becoming more and more prevalent along the Mississippi, and substantial efforts are being made to prevent their introduction to the Great Lakes. Species within the genus Hypophthalmichthys, including: Bighead carp,H. nobilis, Silver carp,H. molitrix; and Largescale Silver carp,H. harmandi are all characterized by having a stout body, large head, small downward-facing eyes (often below the jaw angle), and large opercles. The Bighead carp can be identified by a smooth keel between the anal and pelvic fins that does not extend anterior of the base of the pelvic fins. Bigheads can reach weights up to 45kg (~100lbs) and lengths to 120cm (~4ft).
Ecological Threat: Bighead carp pose a great risk to novel ecosystems for several reasons. First, Bighead carp are large, aggressive fish that are capable of out-competing native fish for resources. Second, Bighead Card are opportunistic feeders that consume high quantities of zoo plankton and phytoplankton. And third, this species is capable of rapid reproduction, laying up to thousands of eggs and one time.
Biology: Bighead carp filter feeder uses their specialized gill rakers as screens to capture their prey. Their ventrally-positioned eyes also offer the fish the ability to see as it swims along the water surface scooping up zooplankton or even phytoplankton. <br></br> Currently, Bighead carp have been recorded in 23 states, (including Texas), and some Canadian waters as well. In Texas, the fish have been reported in Bexar, Jones, and Taylor counties in the Upper San Antonio and Brazos river drainages. Besides large rivers, the carp are also found in smaller tributaries, especially near spillways.
Ongoing Bighead carp invasions most commonly occur from escaped individuals that are raised for aquacultural purposes. However, the fish may also enter open waters by way of bait fish. Juvenile Bigheads may be confused for Gizzard (or Mud) Shads (;Dorosoma cepedianum) or other native fish, and thus may mistakenly be used as bait. Individuals that dislodge from the hook may in turn populate a new habitat.
History: Brought to the United States in the early 1970s, Bighead carp were originally used in aquaculture to control the populations of zooplankton and phytoplankton, or even for use as a food fish. The first record of a Bighead carp caught in natural waters was in 1981 when an individual was caught on the Ohio River below Smithland Dam, Kentucky. That individual was believed to have escaped from a fish farm. Flooding, other natural disasters, and potential negligence has led to the escape of many more Bighead carp over the years.
U.S. Habitat: Bighead carp are native to the large rivers and associated floodplains of East Asia. The Great Lakes and Mississippi River (and others), offer the necessary habitat for rapid growth in the population numbers of these fish.
Distribution
Native Origin: Eurasia (specifically China)
U.S. Present: Widespread across the United States, the Bighead carp has been reported in 23 states, including Texas. Breeding populations have been found along the Mississippi Waterway. It is unknown if breeding populations have become established in the Great Lakes, however Bighead carp have been sighted and/or captured in the area.
Distribution in Texas: Bighead Carp have been spotted in the San Jacinto River, as well as in the Victor Braunig, Fort Phantom Hill, and Kirby Lake Reservoirs.
Management
Managing Bighead carp proves to be a rather difficult task. State and National Government organizations are making a strong effort to prevent the Bighead carp from entering the Great Lakes via the Chicago Waterway System which connects the Mississippi River to the Illinois River, and ultimately leads into the Great Lakes. In order to combat this, the US Army Corps of Engineers have constructed an electric barrier system designed to keep unwanted fish from entering the Great Lakes. The barriers use a pulsing DC current to create an electric field which is uncomfortable for fish to swim through. The hope is that the 3 barrier system can repel the Bighead carp from entering the Great Lakes. Currently, two of the three barriers are completed and operational, so time will tell about the system’s efficacy.
Source: Texas Invasives