Climate change affecting black gill in Georgia shrimp, researchers say

Our Changing Climate

SAVANNAH, Ga. (WSAV) – Researchers believe the recent rise of black gill in Georgia shrimp in recent decades may be linked warmer winters caused by climate change.

Scientists at the University of Georgia Skidaway Institute of Oceanography have utilized the research vessel Savannah to gather information about the condition.

Initially, six years ago, very little was known about black gill. But eventually, it was identified as a parasite responsible for a $20 million hit in the Georgia shrimping industry back in 2014.

Today, evidence is pointing to climate change as a driver for the condition.

According to the UGA Skidaway, black gill was first officially recorded in the mid-1990s. When present in shrimp, it’s believed to feed on shrimp gill tissue which elicits the shrimp’s immune system resulting in darkened gills.

UGA Skidaway Institute professor Marc Frischer and his collaborators have been working with the UGA Marine Extension and Georgia Sea Grant, Georgia Department of Natural Resources, the Georgia Shrimp Association, South Carolina Department of Natural Resources and others to try to learn more about the condition and to help the shrimp industry.

The team scoured records dating back decades ago to look at temperature and water quality alongside harvest performance and shrimp population data.

They found that shrimp with darkened gills usual begin to appear in mid-summer and its prevalence peaks in September and October. The prevalence of black gill declines until January when it virtually disappears, only to reappear the following summer.

Frischer and his team believe the cycle is due to water temperature. This is where climate change enters the picture.

“Understanding of what’s driving it has to do with climate and there’s a number of lines of evidence that its climate change that’s affecting this,” said Frischer.

“Temperature is key,” he added.

One of the most prominent effects of ongoing climate change in the southeastern U.S., including Georgia, has been warmer winters.

Frischer and his team noted that since black gill has been present in Georgia waters, shrimp landings have been correlated with winter water temperatures with smaller harvests occurring when winters are warmer.

“Now that we have this correlation with climate conditions, we can make predictions that say, ‘This is gonna be a good year,’ or ‘This is gonna be a bad year.’ That might really help shrimpers adjust to the nature,” Frischer told News 3.

He and his team have also noted that the prevalence of shrimp black gill correlates with climate indices including the El Niño Southern Oscillation and the Pacific Decadal Oscillation indices. These indices describe the broad characteristics of Earth’s climate.

Frischer says there are still a lot more questions than answers right now, but he’s hopeful the information his team gathers will help shrimpers in Georgia and beyond.

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