Shrimpers battle against a reemerging parasite

By Jill Gambill, Georgia Sea Grant

As shrimpers battle against a reemerging parasite, Georgia Sea Grant is providing research and outreach to battle this threat to Georgia’s largest commercial fishery.

In Georgia, shrimp is king. A cornerstone of coastal Georgia’s culture and economy, shrimping has generated a dockside value of over 8.6 million dollars annually for the state over the past decade. The economic impact to local communities is generally estimated to be three times that amount.

The fishery has long struggled against challenges such as rising costs of fuel, competition with imports and a lack of young people entering the industry. However, something else seemed to be at play in 2013, when fall commercial landings of white shrimp fell by 74 percent compared to the five-year average.

Georgia shrimp fisherman suspect that this decline is at least due in part to outbreaks of black gill, a condition caused by a ciliate, or type of parasite. Although present in Georgia wild shrimp since the early 1990s, studies by the Georgia Department of Natural Resources indicated that approximately 43 percent of sampled shrimp were affected by black gill in October 2013, over 10 percent higher than the long-term average for this month. 

A record amount of rainfall also occurred in 2013, marking the wettest summer and third wettest year ever recorded in Georgia. Questions remain about how the rain, run-off and associated river flow influenced black gill infection rates and the recruitment of juvenile white shrimp in Georgia’s estuaries.

While not harmful to humans and still delicious to eat, shrimp with black gill appear to be struggling. In response, Georgia Sea Grant and University of Georgia Marine Extension have amassed a regional team of scientists, fishermen, resource managers and fisheries experts to explore how the parasite is spreading, what is causing its upsurge and how this is impacting shrimp.

Georgia Sea Grant is funding research by UGA’s Skidaway Institute of Oceanography to investigate the cause, transmission and environmental triggers of black gill. Scientists are inventing parasite genetic testing to better identify the parasite and compare it with ciliates affecting shrimp in North Carolina, South Carolina and Florida. UGA Marine Extension will be hosting regional workshops to educate shrimpers about the parasite and teach safe practices to reduce its spread. In 2014, the project team is also partnering with commercial shrimpers to study black gill in real-time during the shrimping season.

Drawing from over 40 years of collaboration with Georgia shrimpers, Georgia Sea Grant and UGA Marine Extension additionally hosted a workshop to discuss concerns within the fishery. The Georgia Department of Natural Resources subsequently submitted a request to declare 2013 a disaster year for the white shrimp fishery in Georgia. Signed by Governor Nathan Deal and currently under review by the National Marine Fisheries Service, Georgia may be able to pursue disaster assistance funds for shrimpers if the request is approved, potentially leading to low-interest loans, federal assistance to compensate for lost income and additional  research funds.