Off the coast of Rockefeller Refuge. A vertical long line sample is conducted in under 30 feet of water.
16 foot Trawl
LDWF biologists pull up trammel net for red drum sampling.
Oyster Dredge Sample

The Spring-Summer Flood of 2019 That Flowed Through Louisiana Rivers Had Devastating Consequences To The State’s Fisheries

story by Trey Iles, LDWF Public Information


This disaster didn’t have the allure of a hurricane or what you would normally envision from a flood. When you see people displaced by water entering into their homes and brought to rescue in boats, it elicits sympathy.


When Hurricane Katrina made its devastating strike in southeast Louisiana in 2005, the nation was captivated and got behind the rebuilding effort. Billions were spent in repairing the damage and, for the most part, the collective understood.


The flood that happened in Louisiana in the spring and summer of 2019 wasn’t as tangible as most water events simply because the public couldn’t see the damage. But make no mistake, the waters that rolled down the Mississippi River, past the open Bonnet Carré Spillway and into bays and sounds from Mobile Bay to the Louisiana/Texas border were devastating for Louisiana.


These excessive waters caused more than $343 million of damage to one of Louisiana’s biggest economic engines, it’s abundant and bountiful fisheries; shrimp, crab, oysters and other finfish species were heavily impacted.


The headline was, of course, the second unprecedented opening of the Bonnet Carré Spillway, which diverts water from the Mississippi River into Lake Pontchartrain. In two separate openings, the spillway was unplugged for 123 days, a record for the 82-year-old flood control structure. Flooding from the Mississippi River would have unimaginable effects on New Orleans if not controlled by the Bonnet Carré, hence its need. The genesis of the Bonnet Carré was the 1927 flood that submerged New Orleans and much of the surrounding metro area.


“But this was not just a Mississippi River flood event,” said Harry Blanchet, Fisheries Management Administrator. “The Pearl River was flooding. The Pascagoula River was flooding. Keep going. The Alabama rivers were flooding. The Sabine and Calcasieu Rivers were flooding. So we had high water across a good portion of the Gulf Coast.”


Heavy rain that lasted well into the summer and snowmelt across the Midwest that flowed into the Mississippi River Basin and beyond was one of the culprits. It came south and pushed out brackish water in Louisiana’s coastal estuaries. Many of the species – certainly shrimp, oysters and blue crabs – that thrive in that balanced salinity were deeply impacted. But another problem was the unusually wet spring and summer that added to the Mississippi River flows and also to more local drainages.


“The last time we had a similar flood on the Mississippi River was 2011 but that year was dry across the southeast U.S. so the damages that time were not as extensive as they were this time,” Blanchet said.


Hardest hit was Louisiana’s oyster fisheries. Louisiana Department of Wildlife and Fisheries monitoring on public oyster reefs showed mortality as high as 100 percent in several areas across the state. Of that $343 million estimated damage to Louisiana fisheries, $110 million alone was for oysters, said LDWF’s Jason Froeba, Fisheries Research and Development Administrator.


Blanchet, a longtime veteran at LDWF, said he was astounded at the carnage caused by the flood.


“What really shocked me was the scale of impact on our fisheries,” Blanchet said. “Because it was so high and so spread out. And the bad news is it isn’t over. The impacts of this flood are going to last for a few years, especially for oysters. It’ll be some time before they’re back to the size where they can be harvested.”


And be assured it, too, will have economic consequences to the state’s commercial fishing industry that will be felt for some time.


LDWF’s estimate of a $343 million economic loss is more money than the federal government has in the pot to address 2019 fisheries disasters. The National Oceanic and Atmospheric Administration, or NOAA, oversees events like this one. The bad news is only $165 million is available for 2019. And Louisiana wasn’t the only state to have an event labeled a fisheries disaster last year.


“NOAA has to decide how much each state gets out of that $165 million,” Froeba said. “Our estimated document to NOAA was an attempt on our part to say, ‘Here’s everything we lost.’ We didn’t request a specific amount of money but we put a dollar value on everything we lost.


“We also provided that information to Congress and to our representatives in Congress. It shows our dilemma and that consideration may be needed to add more money than is available.”


LDWF’s Monitoring, Documentation Work

As you can imagine, gathering the data to put together Louisiana’s losses in this disaster was a painstaking process that required considerable monitoring. That was the job of LDWF personnel and they did so – and continue to do so – with distinction, LDWF Secretary Jack Montoucet said.


“My heart breaks when I consider the damage done to not only the fisheries resource that has been impacted but also our commercial fishermen,” LDWF Secretary Jack Montoucet said. “Those are some of the hardest working people in our nation and they have such love and passion for what they do. But what encouraged me during this entire process was how hard our LDWF personnel worked in documenting this event then working to assess the damage. We’re talking months and months of work put in above and beyond what was expected. This was in addition to their normal duties.


“I’m certainly not naïve enough to think this will all go away magically when money is made available to rehabilitate the fishing industries of our state. But they can, without equivocation, know that LDWF will be by their side every step of the way and will work with them from here on out.”


As Montoucet said, LDWF biologists and technicians put in long hours, days and months to record the effects of this disaster.


It all began when the spillway opened on Feb. 27 when waters roaring down the Mississippi River became perilously close to topping the levees designed to hold them. It remained opened until April 11. But continued rains in the nation’s midsection forced the spillway to be reopened again on May 10, something that had never happened before. The spillway was shuttered on July 27. But damage caused by the inundation of the freshwater to the coastal estuaries was done. And was continuing.


LDWF personnel were there throughout and well into August measuring and documenting the effects.


Even in normal times, the LDWF Marine Fisheries crews in the Lake Pontchartrain Basin are busy. This year, however, was extraordinary. They normally take a large number of fishery-independent samples, monitoring the fishery stocks of that basin. But during the disaster they took an incredible 1,961 samples.


These samples monitored impacts associated with the Bonnet Carré Spillway opening and also other flood inputs into the system. It included 472 oyster dredge tows, 371 oyster square meter samples, 363 16-foot trawl samples, 30 crab trap sets, 10 investigations of marine mammal and fish kill reports and 130 hydrology readings around the Lake Pontchartrain Basin, from the Mississippi state line to the bird’s foot delta of the Mississippi River. Even though the spillway was closed on July 27, monitoring continued through Aug. 30.


“We had a lot of people busting their tails,” Blanchet said. “Normal work got pushed to the back burner. Certainly our Area 1 folks out of our Lacombe and New Orleans office  deserve a lot of credit for all the work that they have done. They’re collecting the data to make recommendations on setting shrimp seasons, oyster seasons, monitoring abundances of saltwater finfish, all their regular duties. Then this is piled on top of that. It wasn’t easy on any of them. But they did a great job.”


Blanchet said it was important to constantly monitor salinity levels and what the impact they were having on the fishery. He cited oysters as an example.


“Our regular samples characterize what is going on in the (Lake Pontchartrain Basin),” Blanchet said. “But for instance, if you have oysters dying, you don’t want to only monitor that just once a month because you might miss the mortality event. So one time you sample and you’ve got oysters. The next time you pick it up, you have shells. That’s when you miss some valuable data. What you need to find is a freshly dead oyster to be able to document that mortality. Hence the need for increased sampling frequency.”


The data gathered showed the devastating consequences from the flood not only in the Lake Pontchartrain Basin but throughout the state.


As mentioned before, oyster crops were devastated. The reason is simple. Most estuarine species will move to water with higher salinity levels when fresh water pours in. Oysters, of course, cannot.


Blanchet said the late spring and summer flood waters caused most of the damage to the oyster crop. Oysters can handle some influx of fresh water and can make do when the water is cool.


“We did see some early mortality but it’s that June-July-August high water that is terribly impactful,” Blanchet said. “It’s hotter. Oysters can survive for a while when it’s cool and they get a little freshwater. The temperature is low so they’re not metabolizing fast. There is lower dissolved oxygen in hot water than in cold. And because oysters are a cold blooded animal, their metabolism elevates when the water is warm. So they require more oxygen.


“Those late spring floods are what gets us. The winter floods don’t have the same level of impact.”


Even though shrimp, crab and finfish can move, those species were affected by the flood water, too. That was seen in harvest.


Statewide volume and value of brown shrimp landings were down 34 percent and 44 percent, respectively, when compared to the five-year average.


Commercial blue crab landings decreased across the state in all basins, with declines ranging from 14 to 84 percent in individual basins.


Commercial black drum landings were down by 51 percent in the Vermilion/Atchafalaya Basin. Department sampling also indicated the catch per unit effort of spotted seatrout was 66 percent below average in the Vermilion/Atchafalaya Basin and 50 percent below average in the Pontchartrain Basin.


The white shrimp season closed in December and, anecdotally, it doesn’t appear that it will have been a good one, Blanchet said. The final harvest numbers were unavailable as of this writing.


“August was actually a pretty good month if you looked at the landings for white shrimp,” Blanchet said. “But that was because the season opened a week and a half before it normally would. So for the month of August harvesters had more time to fish. But if you look at it on a per day basis, it was poor.”


Blanchet said he was surprised that the impact on white shrimp was as high as it was. That’s because river flood impacts generally don’t affect white shrimp recruitment and the species can tolerate lower salinities.


Totaling The Loss

The monitoring and recorded losses by LDWF staff in the field was then taken by LDWF fisheries staff in Baton Rouge and an economic impact was calculated. Froeba’s staff would take trip ticket landings from a certain month and put together an estimated accounting of reduction in landings and the accompanying reduction in value.


“We did that for quite a while until the Secretary of Commerce declared a fisheries disaster (which occurred in September),” Froeba said. “Up to the point of the declaration, we were doing those monthly reports to prove to NOAA that there was a fisheries disaster. After the disaster was declared we needed to document what the actual loss was and document how we came up with that calculation. That started in September.”


The process lasted about six weeks, going back and forth with NOAA and looking at different ways to calculate loss. Of course, each fishery’s loss had to be viewed differently from another.


“What’s appropriate for the oyster fishery might not have been appropriate for the shrimp fishery in terms of the time frame and the data sampled,” Froeba said. “There are different seasons and different biology for each animal. We had a lot of people involved in the mix, data management staff, our socioeconomic section, just to name a couple.”


The group worked six weeks in preparing the document and the estimated $343 million loss. The back-and-forth with NOAA took another two weeks before the final product was finished the Wednesday before Thanksgiving of last year.


“All in all, it was probably two and a half months worth of work,” Froeba said. “It was a lot of hard work. A lot of us had to put things aside to focus on that.”


Going forward

How much money will flow from the federal government and wind up in commercial fishermen’s hands is anyone’s guess. Froeba said money is coming but the devil is in the details on how it will be divvied out.


Once those details and parameters are set, LDWF will collaborate with the federal government and the state’s commercial fishermen to determine the plans to be used for distributing the funds. Up until now, Froeba said, the focus has been on the big picture, the entire economic loss incurred. Going forth, it will be determined how much each fishery will receive and what types of programs will be approved.


More troubling, however, is the future of the fishery. Time and again, it has proven to be resilient and able to overcome these types of disasters. The problem is the disasters seem to be more common. As an example, look at the history of the Bonnet Carre Spillway.


First opened in 1937, it was utilized only eight times in 71 years through 2008. Since then, it has been opened six times. Even worse, its gates have been released four times in the last four years, including twice in 2019.


“Each fishery will need time to heal, especially the oyster fishery,” Blanchet said. “But that doesn’t take into account any future floods that might hit us. So it’s concerning.”


Montoucet said that’s why it is important for LDWF to continue to adapt to changes and be prepared to adjust.


“But I am confident we can do that,” Montoucet said. “Our staff at LDWF is nimble and able to confront the challenges that face us. I’ve seen that time and again since I’ve been here. I have so much confidence in them just by watching their performances during events like this.”

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