Fish Introductions Can Be Harmful and Are Illegal

[NCangler]

RALEIGH, N.C. (July 11) – With the recent discovery of another non-native fish in the Catawba River, the N.C. Wildlife Resources Commission is reminding the public that adding fish to public waters can have irreparable ecological consequences and is illegal without a stocking permit issued by agency.

Many fish introductions are made by anglers hoping to improve a favorite fishing spot and by aquarium owners who decide to release their fish in the nearest pond, lake or river.

Fisheries biologists suspect this was the case with a fish caught on June 28 from the Catawba River in Mount Holly. Originally misidentified as a piranha, the fish, reeled in by Gastonia resident Jerry Melton, was actually a pacu, a popular aquarium fish similar in appearance to the carnivorous piranha but with an appetite for vegetables and fruit.

Because the two species look so much alike, it’s often difficult to tell them apart. Jacob Rash, a fisheries biologist with the Commission, confirmed that the fish caught from the Catawba River was a pacu after examining the frozen specimen on July 6.

“The biggest difference between a piranha and a pacu is the teeth,” Rash said. “The pacu has molar-like teeth, with two rows of teeth on its upper jaw, and the piranha has only one row of sharp teeth.”
While a pacu doesn’t have the sensationalism of a piranha, its appearance in the Catawba River still worries biologists; both species are native to Central and South America, so neither should be found in North Carolina waters.

“Anglers should be concerned about maintaining the integrity of their favorite fishing holes,” Rash said. “Whether it’s aquarium fish discarded into the river, or bait fish transferred from one lake to another, these illegal fish introductions can have disastrous impacts on native fishes.”

Introduced fish can thrive in their new environment and negatively impact established fisheries by competing with them, eating their young, transmitting disease and altering their genetics if they interbreed.

Examples of illegal introductions having unintended effects are numerous:

White perch, a native to the coastal waters of the Atlantic Ocean, have been stocked into inland waters of North Carolina where they feed on the eggs of largemouth bass, crappie, striped bass, sunfish, walleye and white bass;
Spotted bass, a favorite of anglers because of their aggressive nature, can out-compete resident largemouth and smallmouth bass populations, as well as hybridize with smallmouth bass;
Blueback herring, a popular bait fish established by anglers in Chatuge and Hiwassee reservoirs, have been known to eat larval fish and fish eggs, leading to a steep decline in walleye and white bass reproduction in Hiwassee Reservoir.

“It takes only one introduction of fish from a bait bucket or aquarium to upset ecological stability and harm fishing,” Rash said.

For this reason, the Wildlife Commission in 2005 passed a regulation that required anyone interested in stocking a public, inland fishing water to obtain a stocking permit first.

The requirement protects native or legally established aquatic species from the potentially damaging effects of unauthorized stockings by allowing the Commission to assess, on a case-by-case basis, the impacts a proposed stocking may have on an established fishery.

However, as unwanted species continue to appear across the state, some people have not gotten the message that fish stockings are illegal and harmful.

“We’re asking people to do their part to help prevent illegal fish introductions by spreading the word about harmful impacts and reporting wildlife violations in North Carolina to 1-800-662-7137,” Rash said. “By acting responsibly and working together, anglers and the N.C. Wildlife Resources Commission can help maintain our fishery resources for future generations of anglers.”

For more information on fishing in public, inland waters, contact the Division of Inland Fisheries at 919-707-0220 or visit the Commission’s Web site, www.ncwildlife.org.