Exotic species attract watchful eyes - San Antonio Express-News

Posted: 17 Sep 2020 04:05 PM PDT

The Texas Parks and Wildlife Department presented a myriad of potential regulation changes that focus on the management of exotic aquatic species at the most recent commission work session.

"We think that we've got a comprehensive rule package that addresses not only reorganization of the rules, to make them more accessible, but also some of the needs in the regulated community and some conservation concerns," said Monica McGarrity, senior scientist for aquatic invasive species management in TPWD's inland fisheries division.

A regulation change that directly impacts Texas anglers regards the possession of exotic species. Anglers who catch exotic fish such as tilapia or grass carp are currently required to immediately gut or behead them. A proposed change would allow anglers to kill these fish by other means, including putting them on ice.

Another regulation change regarding possession involves lakefront landowners. The change would allow these landowners to possess and transport invasive aquatic plants and animals, such as water hyacinth, salvinia, zebra mussels and apple snails, without permit, provided they are either composted or destined for disposal and secured properly.

TPWD is proposing significant changes for pond stocking of tilapia, which is typically done to provide forage for bass.

Currently, Mozambique tilapia can be pond stocked without a permit. But rampant hybridization has made species identification difficult.

"It's pretty much impossible to confidently distinguish between Mozambique tilapia and the other species that are currently present in aquaculture," McGarrity said. "So this puts an undue burden on the aquaculturist as well as those people who might be in possession of Mozambique tilapia."

The proposed changes would allow three more species to be pond stocked without permit: blue, Nile and Wami.

To balance the potential ecological and economic impacts, the department is seeking to set up geographical management zones.

I-35 as dividing line

The area roughly west of I-35 would be considered a "conservation zone," with a prevalence of imperiled fish species that could be negatively impacted by tilapia. Pond stocking in this area would require TPWD approval, which is not associated with a fee or permit but would be done to ensure the tilapia can't escape.

The area roughly east of I-35 would be the "stocking zone" and would not require approval. East Texas has much more significant economic importance for pond stocking and fewer imperiled fish.

Another proposal would allow possession of those four tilapia species without a permit in aquaponics setups, providing nutrients for plants, as long as the fish are in a closed system and are not sold or transferred live.

Reporting for tilapia aquaculture also no longer would be required with the proposals.

Currently, aquaculturists in the state must renew permits annually, a hassle for those who have been in the business for decades.

"They've been good actors, they've had no violations, and they still have to go through that administrative burden every year," McGarrity said.

TPWD is proposing three- and five-year permit renewals, like how the department handles deer breeder permits, to make things easier for aquaculturists. Commercial aquaculture facilities would be subject to inspection at least once every five years.

The proposed rule changes also would eliminate the permit requirement of having an actual facility for pond stocking sellers, which would allow them to possess the fish for a short time after purchase from an aquaculturist and before delivering to a customer.

The department is moving pre-emptively in modifying its list of controlled aquatic species.

"Prevention, such as in the form of regulations, is critical, because new invasive species introductions follow what's known as an 'invasion curve.' By the time most species are detected, the infestation is already outside of the brief window when rapid response and eradication may be possible for some species," McGarrity said at the work session.

"After that point, the situation often rapidly progresses into the more costly, long-term active management phase, if such management is even possible."

Not in love with hearts

TPWD is aiming to make seven additions to its controlled exotic species list.

Two aquatic plants — crested and yellow floating hearts — are the only species of the seven that have made a Texas encroachment. Crested floating hearts have been detected in Lake Houston, Lake Conroe, Caddo Lake and Lake Athens. Yellow floating hearts are found in Moss Lake and the Louisiana side of Toledo Bend.

"Those are species that have been introduced into our lakes and become problematic," McGarrity said. "They can develop significant infestations that can impede boater access, clog areas around docks. It's important to have those on our list to make sure that they can't be moved."

The department has used herbicide to manage floating hearts successfully, even eradicating some new infestations when administered early. McGarrity stressed the importance of boaters cleaning, draining and drying their vessels.

Golden mussels are set to join the list. And although the species has yet to arrive in the U.S., it is considered an imminent risk.

Zebra mussels likely entered the country via the ballast water and anchors of ships in the Great Lakes before they began a widespread infestation that includes Texas. Golden mussels could make a similar invasion and would have comparable negative ecological effects.

"This species has slightly different tolerances. And ... it could invade more saline waterways and become even a little more widespread than zebra or quagga mussels," McGarrity said.

Four fish species are proposed to be designated as "harmful or potentially harmful exotic fish," which would restore federal Lacey Act protections that had been invalidated and make transporting them across state lines a federal violation.

Stone moroko, European perch, Amur sleeper and Wels catfish were picked because they were identified as having a strong potential to survive in Texas and pose significant risk to native species.

The most recognizable is perhaps the Wels catfish, which has been featured on Animal Planet's "River Monsters" and would be an extremely destructive invasive.

"It grows to massive size, a couple hundred pounds. It would be a top predator. It can prey not only on fish, but even wading birds," McGarrity said.

None of the four fish species has been introduced to the U.S. or currently is considered a threat to Texas.

"This is just a proactive measure. There are pathways by which those species could be introduced into the U.S., and if they were, then having them on our list would protect Texas waters from those species being brought into the state from another state," McGarrity said.

matt.wyatt@chron.com

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