Clean, Drain, Dry best solution for slowing the movement of invasive species

STEVE KNIGHT/ INVASIVE AQUATIC SPECIES such as giant salvinia in places like Caddo Lake and zebra mussels can be an issue for fishermen and recreational boaters. Clean, drain and dry can prevent the spread to other lakes.

As part of its 2016-17 budget, Texas Parks and Wildlife Department was given an extra $6.3 million to battle aquatic invasive species.

The truth is, fishermen and recreational boaters can have almost as big of an impact in slowing down the spread of some of these invasives at no cost to anyone.

From giant salvinia in East Texas and South Texas, zebra mussels in Central Texas, saltcedar in West Texas and to a lesser degree hydrilla around the state, Texas fishermen and boaters are facing some major issues that could affect fishing as well as access.

To all boaters giant salvinia has to be the poster child for the worst invasive vegetation. First found in Texas in 1998, it is now on 16 lakes statewide. Caddo Lake is by far the worst. At its worst it has covered more than 6,000 acres primarily on the shallower Texas side of Caddo.

Because of its ability to double in mass in a matter of days the giant salvinia on Caddo requires constant spraying of chemicals during the growing season. TPWD has also enlisted the use of giant salvinia beetles in an effort to at least slow the plant. Still there are areas of the lake that have not been accessible by boat in years.

Including efforts this year, the department will have spent $1.2 million over four years for chemical treatment on Caddo alone.

Giant salvinia grows in a floating mat that is impenetrable by any type of boat other than an air boat.

In its 2016-17 budget the department was allotted $3.3 million for battling giant salvinia. Besides Caddo, other problem lakes are B.A. Steinhagen, Sheldon, Murvaul, Raven and a number of smaller lakes stretching from Beaumont to Houston.

Unlike giant salvinia, zebra mussels are more of hidden problem in Texas lakes.

"We have nine lakes in the state that we classify as being infested, which means those water bodies have reproducing populations established," said Brian VanZee, TPWD Inland Fisheries regional biologist. "We have another five lakes that are classified as positive, which means zebra mussels or their larvae have been found more than once, but have no evidence of reproduction. We also have three lakes that are classified as suspect, which means zebra mussels or their larvae have been found there once." 

Zebra mussels are an aggressive Eurasian species that made it into the United States in the 1980s in the ballast of cargo ships. There is an industrial concern about the zebra mussels because they can collect on water intakes in lakes shutting them down. In Texas, this would primarily be intakes for water supply systems. If the mussels become established it could result in a large expense to taxpayers to correct the problem.

"Last year, zebra mussels were found in four new lakes, Stillhouse Hollow, Eagle Mountain, Worth and Livingston.  My guess is that lakes Worth, Eagle Mountain and Livingston are likely the result of downstream migration from upstream infested reservoirs that experienced high flows as a result of all the rain we had in the springs of 2015 and 2016. However, Stillhouse Hollow is likely the result of an introduction by a boater given that Lake Belton is in such close proximity to it," VanZee said.

Zebra mussels are suspected in lakes from Cedar Creek, Livingston and Lake Fork in the east, Bridgeport to the west, Texoma to the north and south to Belton and Stillhouse Hollow.

Initially there were concerns that the zebra mussels could harm freshwater fishing by impacting both fish species and aquatic vegetation. The mussels are filter feeders and consume the food sources for many young fish including bass fingerlings. They can also increase water clarity that could impact plant communities. However, that may not be the case in Texas.

"From a fisheries perspective we really haven't seen much of an impact to say forage fish or game fish populations in the infested reservoirs. Here in Texas zebra mussels tend to have faster growth rates and shorter life spans than in other parts of the country. As a result it appears that zebra mussel populations in Texas may experience a shorter boom and bust cycle than invasive species typically experience when invading a new lake," VanZee said.

However, they can still impact both recreational and fishing boats by attaching to hulls or possibly engines and blocking water intakes. They can also attach to piers making them dangerous to swimmers and a nuisance to fishermen getting their lines frayed or cut on the mussels' sharp shells.

So how can boaters help? With the summer boating season, they remember three words - clean, drain and dry. Clean boats and trailers of vegetation when pulling out of a lake, drain all water before leaving the ramp and let the boat and trailer dry before launching in another lake. These three steps will help from carrying unwanted species like giant salvinia and zebra mussels from one lake to another.


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