Hidden Louisiana is the water highways many residents never get to see. But our way of life depends on wetlands like the Barataria-Terrebonne Estuary.

Wildlife agents from Louisiana, Mississippi and Texas use a seine to search for invasive species that could threaten Louisiana's natural environment.

They are part of a team of 50 federal and state experts spending a week combing the entire estuary, from the Mississippi River to the Atchafalaya, in what is called a rapid assessment project. They are seeking data about the spread of plants like water hyacinth and giant salvinia that can overwhelm native plants and choke Louisiana waterways.

"They can do a lot of damage especially growing so thick on the surface of the water, turtles and frogs can't come up and grab a breath of air, it shades out all the plants underneath. It impedes boat traffic," said Michael Massimi, from the Barataria-Terrebonne National Estuary Project.

And there are other invaders like silver carp, a fish that can grow to 40 pounds and actually injure people.

"They grow so large and are filter feeders, so they eat larval fish which are our native species, and they're eating plankton which is food for our larval fish, but also they have this odd habit of jumping clear out of the water, and it’s a very big fish, so boaters have actually been injured,” said Massimi.

How important is this survey? Well, this estuary is crucial to Louisiana, for everything from coastal protection to the seafood dinner you are planning to have this weekend.

"There's many species of offshore recreational fish and commercial fish who use the estuary to spawn,” said Massimi, “so all their babies are in the estuary until they go back out to become adults. In terms of hurricane protection? Incalculable."

The scientists found far too much evidence of invasive plants in the estuary, but were pleased about the lack of foreign fish and invertebrates.

"Well, so far we haven't collected an invasive species in our seine samples yet, but if we were to collect one this would be a likely spot because this is the Intracoastal Waterway,” said Vince Guillory, from Louisiana Wildlife and Fisheries.

"Our biggest goal I think was to look for the apple snails, simply because we have found them in other parts of the Barataria system,” said Earl Melancon, a Nicholls State biologist. “But we've been through the Intracoastal Canal all the way to Morgan City, and have been into the upper part of the Barataria system, and have yet to find an apple snail."

It will take months to examine the data gathered here. But the goal is to train outdoors experts to spot new invasive species, and set up a rapid response team to take action before they become a threat.