Freshwater diversion could hurt Barataria dolphin population

Population of dolphins in Barataria Bay could drop by 34%

Freshwater diverson project could impact La.'s dolphin population

NEW ORLEANS (WVUE) - As plans continue for a freshwater diversion project, considered a major building block for the coast, a government study shows the state’s dolphin population could take a hit. The freshwater may hurt the dolphin population in the short term, but one expert points out that’s not the whole story.

Large amounts of freshwater after repeated openings of the Bonnet Carre Spillway led to unusually active dolphins in 2019. Dr. Mobi Solangi with the Institute for Marine Mammals Studies in Mississippi explained it was a coping mechanism. He said, “That’s how they scratch. You know they don’t have fingers like you and I when they have a parasite or something they go up and hit the water.”

We saw many reports of dolphins with skin lesions and a number of dead dolphins during and shortly after that event. George Rick is a charter captain and president of the Save Louisiana Coalition. He said, “Here in St. Bernard parish, I personally documented 38 dead.”

Dr. John Lopez has studied coastal Louisiana for decades. He said, “NOAA has concluded that freshwater did impact some of those dolphins from the 2019 unusual mortality event.”

A new National Oceanic and Atmospheric Administration or NOAA study released in December shows dolphins in Barataria Bay could see a similar fate with the planned Mid-Barataria Sediment Diversion. The National Marine Fisheries Service is a department under NOAA. Their study identified groups of bottle-nosed dolphins in the bay and modeled changes in the water’s salinity. The results show the population could decline by 34 percent. The estimated population of dolphins currently in Barataria Bay is about 2300.

Ricks said, “Close to 700 dolphins being killed by this freshwater.” The Save Louisiana Coalition is vocal against diversion projects to build the coast. “My concern is not only because of the dolphins. That’s bad enough, but what it’s going to do to our seafood industry,” said Ricks. They see dredging as a more viable option.

Lopez said, “There is not a tool in our toolbox for coastal restoration that there is not some negative aspect to it.” He said rock jetty’s interrupt the shoreline habitat and dredging disturbs the ecosystem in the bottom of the water column.

“So there’s always some trade-off. Don’t read this into saying that dolphin is necessarily a tradeoff kind of dynamic reigniting the system may in the long run actually benefit the dolphin, said Lopez.

Lopez said dolphins live along the coast because of the food provided by the wetlands. While current populations may suffer from freshwater, preserving the overall habitat is crucial.

Ricks said with limited time, money, and resources he worries. He said, “Our heritage, our fishing heritage in the state is at stake here and we only got one shot to get it right.”

The Mid-Barataria Sediment Diversion is a cornerstone of the state’s Master Plan for coastal restoration. As studies and permitting continue construction is expected to begin in spring 2022 with funding from the money meant to be used to restore coastal resources damaged by the 2010 Deep Water Horizon BP oil spill.

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