Louisiana Department of Wildlife and Fisheries will check trout numbers in Lake Pontchartrain

on February 12, 2012 at 3:15 AM

Bob Marshall fishes trestles with Dudley Vandenborre The Times-Picayune's outdoors writer learns trout fishing the trestles from the master, Dudley Vandenborre.

Dudley Vandenborre -- guide, lure-maker and Lake Pontchartrain angler extraordinaire -- was pulling speckled trout from 62-degree water Wednesday along The Trestles, proving once again his No. 1 rule for catching trout in the lake: Specks start biting when the water gets hotter than 57.

But because this was the first week of February, and those temperatures typically don't rise past the 57-degree line until late March, that brought up questions that have been the center of angler debates for generations:

Do these Trestle trout stay in the lake year-round, or do they migrate to and from other parts of the estuary?

"I think they're always here, but they just don't feed actively until that water temperature goes above 57," Vandenborre said. "I know some people think they come in and out. I used to think that, too. But now I think they're always here."

The Louisiana Department of Wildlife and Fisheries and LSU are about to embark on a research program that should settle that debate, and many others.

Beginning next week, the agency will place dozens of data receptors around Lake Pontchartrain that will record the travels of speckled trout soon to be carrying special acoustic tags. The plan is to blanket the lake with receptors from the Pass Rigolets to Pass Manchac, along the shorelines, over remaining grass beds and around artificial reefs and structures such as bridges.

The receptors will record the date, time, water temperature and depth each time one of those tagged trout passes within its range. The data will be retrieved by angler-volunteers on a regular basis.

When that information is added to other critical habitat data such as salinity levels, air temperatures and weather conditions recorded by other devices, LSU graduate students interpreting the data may be able to expose secrets of Lake Pontchartrain trout that have long puzzled anglers.

For example:

Do those Trestle trout actually migrate into the lake in spring, as was long believed, or are they year-round residents?

Does cold weather drive the specks into deeper water in nearby canals and bayous, or do they seek deeper portions of the lake?

Does low salinity associated with spillway openings drive specks out of the lake, or just to other parts of the lake?

Do adult specks move closer to the Gulf of Mexico during spawning season, or do they use areas of the lake that provide the right salinity?

Are there seasonal migrations to different parts of the lake? And if so, are they tied to weather events?

How effective are the artificial reefs in attracting speckled trout?

Which lake bottom habitats are most attractive to specks?

Do the fish segregate along age and gender lines?

Do larger trout favor specific habitats?

LDFWF Assistant Secretary Randy Pausina is confident those answers will be coming, because this type of research has already provided them information for Calcasieu Lake at the western end of the coast.

"Calcasieu was an ideal test site because it has only two entrance/exit points, which meant we had better control of keeping those tagged fish in the area (of research)," Pausina said.

"With that success, we wanted to come to the eastern part of the state. But we couldn't use an entire estuary, say like Barataria Bay, because it was so large and had so many exit points, we just couldn't cover them.

"Lake Pontchartrain is better. It's much larger than Calcasieu, but it doesn't have so many exits as Barataria. And we can monitor the passes (Rigolets, Chef and Manchac) pretty good.

"The results should be really interesting."

They certainly have been for Calcasieu. Among the findings there:

Trout, especially the larger fish, preferred the oyster reefs and muddy bottoms of the open lake to the smaller bayous, canals and bays in associated marshes.

Larger trout preferred reefs far more than the smaller fish.

The use of habitat types was definitely seasonal.

Artificial reefs were most often crowded in the spring and summer.

Trout seldom moved more than 32 miles.

All of that can be put to good use by anglers to improve the quality of their fishing experiences, which has long been a main thrust of Pausina's work in fisheries management.

But the results will also add to the knowledge his office can use in recommending management decisions after environmental events such as hurricanes, freezes, spillway openings and oil spills. And that kind of detailed information will become even more important if our habitat base continues to erode, because fish populations will begin to drop.

Of course, pulling the curtain back on the secrets of speckled trout also poses a certain threat to angler egos. For example, the standard explanation I've offered for my often slim catches has been the claim that fish have such respect for my angling skills, they clear out when I'm in the area.

The results of this research project could well have me looking for another cause, or I'll have to accept what Vandenborre has often told me in those situations: "It's not the fish, Bob."