Assessing the socioeconomic effect of black gill on commercial shrimp trawlers in Georgia by assessing infection rates and analyzing shrimper observations using survey data

Black gill is a disease that occurs in commercial shrimps along the Atlantic Coast of the United States. Caused by a parasitic ciliate that lives under the gills of shrimp, it has been observed in South Carolina between August and October, a period which overlaps with the state offshore shrimping season in Georgia (potentially May 15-December 31; possibly extended into January or February). The infection does not cause shrimp mortality directly; however, it impairs respiration and reduces the energy output of shrimp. This makes shrimp more vulnerable to predation and environmental conditions such as extreme temperature fluctuations. Still, shrimpers have reported catching dead shrimp. Consuming a parasitized shrimp has not been proven to affect humans, but the black discoloration caused by the parasite may make the shrimp product less marketable if consumers are not accustomed to seeing discolored shrimp. Shrimp fishers may choose to take the heads off of the shrimp in a process known as "heading" before selling to markets or sell the shrimp as is. Heading represents more effort on the part of shrimp fishers, whereas selling shrimp as is leaves the task to retailers. This extra effort may affect overall cost for the shrimper or the final market pathway to sell their catch. The objective of this study was to determine the prevalence of black gill in Georgia shrimp over the course of the state offshore commercial shrimping season, and to assess whether the presence of the disease was a factor that impacted the marketability of shrimp and had socioeconomic consequences for shrimpers. The socioeconomic effect of black gill on commercial food shrimp trawlers in Georgia was explored using two chapters. In the first chapter, the infection rate of black gill in Georgia shrimp trawling areas were observed using the Georgia Department of Natural Resources (GADNR) data and observations of surveyed Georgia commercial shrimp trawlers. In the second chapter, Georgia commercial shrimp trawlers were surveyed for their perceptions and behavior related to their experiences with black gill. The outcomes of this study evaluate the socioeconomic impacts that black gill disease has on shrimpers.