With the fishing rodeo season in full swing, and the big Fourth of July events scheduled for Fourchon and Lake Charles, fishermen are wondering what, if any, effects will come from another in what seems to be a long list of environmental misfortunes to hit the Louisiana coast.

Six years is hardly an eternity, but since 2005, four major storms, our nation’s largest oil disaster and, this year, a months-on-end slug of high water from the Mississippi River have brought something more than a string of bad luck.

This year’s heavy river flow is a naturally occurring event, but one scientists are predicting will spawn the largest-ever measured Gulf of Mexico “dead” zone, and that’s not something fishermen want to hear.

How bad was it? The last time the Mississippi River was high enough to force the openings of both the Bonnet Carre and Morganza spillways was 1973, 38 years ago.

What will the river’s effects have on the marine organisms that make Louisiana the most productive estuary for commercial and recreational fishermen in the lower 48 states?

“We hate to speculate, because we never know what will happen,” Department of Wildlife and Fisheries assistant secretary Randy Pausina said. “It really depends on the volume of water over time.”

For Pontchartrain-basin waters, Pausina said a heavy volume of Bonnet Carre Spillway water into Lake Pontchartrain, through The Rigolets and into Lake Borgne coupled with southeast winds and slack tides could touch off a string of events he called a “worst-case scenario” involving dissolved-oxygen robbing algae blooms.

Low-dissolved oxygen is a major cause of fish kills like the ones that happened in Pontchartrain after the Bonnet Carre was opened in 2008.

Like last year’s BP-Deepwater Horizon oil disaster, Pausina said the LDWF’s major concern is with oysters. He added that finfish, shrimp and crabs have the ability to move and, most often, will move to more desirable environs.

“Oysters can’t move and once the water gets below five parts per thousand (saltwater), the oysters close up and won’t open,” Pausina explained, adding that oysters must open their shells to feed.

“Depending on water temperature, the cooler the water the longer the oysters live, but if the conditions don’t get right, the oysters have between 5-10 days before the oysters will die,” he said.

Now that Bonnet Carre and Morganza are closed, is the threat to marine fishes past?

Pausina said no.

“What we need is a front to come through after the spillways are closed. That helps break up the (freshwater) and pushes it off (into the open water of the Gulf),” Pausina said. “What we’ve seen in the past is that the harm depends on the wind. We hope the animals (fishes) are pushed with the water out to the passes. Remember we had localized (fish) kills in 2008. Generally, they were mullets of pogeys that moved into subdivision canals and got stuck in there and they sucked up all the oxygen.”

By the end of the month, Pausina said marine biologists will know more about the effects on the shrimp season. That’s because commercial shrimpers are required to post trip tickets that will indicate their total catch during the current spring inshore season.

Pausina said a major effect on speckled trout might not be seen until the next few years. That’s because Pontchartrain’s basin waters are a major spawning area and a strong incoming tide in needed to carry fertilized eggs into the marsh. Too much freshwater throughout the system could reduce that movement.

Golden Meadow-Fourchon Tarpon Rodeo

Admiral: Chris Moran

Where: Moran’s Marina, La. 3090 (off La. 1), Fourchon

When: 7 p.m. Thursday, rodeo welcome party.

Friday, Fishing begins at sunrise. Weighstation scales 10 a.m.-8 p.m.

Saturday, 10 a.m. weighstation scales open; 4 p.m., scales close Children’s Division; 5 p.m., Children’s Division awards; 5 p.m., scales close Scuba/Skin Division; 6 p.m., scales close Hook & Line Division; 6:30 p.m. Scuba awards; 7:30 p.m. Rodeo Awards.

Tickets: $25 adults, $10 children (ticket sales close at 10 a.m. Saturday)

Ticket locations:

Moran’s Marina

Larose: B&B Hardware

Cut Off: H&R Sports Bar

Golden Meadow: Golden Meadow True Value, T-Pops

Leeville: Gail’s Bait Shop, Griffin’s Station, TYDS

Cheniere: Camardelle’s Bait Shop

Grand Isle: Sand Dollar Marina

Online: www.gmfourchontarponrodeo.com

ELIGIBLE SPECIES

(Hook and Line divisions)

BIG GAME DIVISION

Tarpon (over 60 pounds), Shortfin Mako Shark, Yellowfin Tuna, Blue Marlin (Tag & Release only), Wahoo, Dolphin, White Marlin

SHORELINE DIVISION

King Mackerel, Spanish Mackerel, Cobia, Bluefish, Red Snapper, Blackfin Tuna, Mangrove Snapper, Barracuda, Jackfish (Crevalle), Bonita, Grouper, Rainbow Runner

INSIDE DIVISION

Speckled Trout, Bull Red (over 27 inches), Rat Red (under 27 inches), Flounder, Bass, Gafftopsail Catfish, White Trout, Sheepshead, Drum, Croaker, Bream

First, second, and third places in all categories except Tarpon, Redfish, Speckled Trout & Bass (first through fifth places), plus awards for outstanding fisherman in Big Game, Shoreline and Inside divisions.

TAG & RELEASE DIVISION: Decided by points (500 points, blue marlin; 200 points, white marlin; 250 points yellowfin tuna/limit 2 per day) & tarpon division by tags. Captain’s Award for boat with the most points on leaderboard in Big Game, Shoreline, and Inside Divisions

SCUBA DIVING DIVISION

Grouper, Spadefish, Barracuda, Jack Crevalle, Triggerfish, Cobia, Red Snapper, Miscellaneous (excluding tarpon and billfish), Mangrove Snapper, Sheepshead, King Spearfish & Team awards.

CHILDREN’S DIVISION

Eligible species are those listed in Inside Division, except no category for Bull Reds.

Outstanding Fisherman and Fisherette trophies.