Semester of Graduation
Master of Science (MS)
Renewable Natural Resources
Fisheries produce important impacts around the world through the exploitation of a wide range of species. In Louisiana, crayfish is the most emblematic crustacean and supports a multi-million industry based on pond culture and harvest from natural habitats. Although the economic value (USD) of wild-harvested crayfish has decreased from 10% to 3% of total crayfish value from 2013 to 2015, wild harvested crayfish are highly desired by many consumers and have a strong socio-cultural importance in Louisiana and other Gulf of Mexico coastal regions. This project evaluated harvesting practices by: 1) field observation and mapping of harvest sites in southwestern Atchafalaya River Basin; and 2) directed interviews with individual harvesters. Field observations included trap locations, water quality, habitat components, and fishery independent sampling. Weekly field observations were conducted along four transects across a gradient of water quality over two harvesting seasons (2015 and 2016). I also assessed floodplain connectivity with river water sources by conservative tracers sampled at each water quality site biweekly during 2016. Directed interviews of 23 harvesters provided data on fishing strategies, factors used to decide when to start fishing, and selection of harvesting locations. Trap density was first assessed for spatial autocorrelation by Pearson Chi-Square Quadrat Test and Nearest Neighbor Tests and then by generalized linear models including water quality, habitat, harvester answers and conservative tracers. Analyses demonstrated that trap locations were not random, i.e., traps were set in relatively clear water (NTU < 69.4) in in depths from 1-3 m or 3-3.6 m. Very few traps were set high turbidity water regardless of depth. Trap density was positively associated with river water inputs, based on conservative tracer results. Harvester interviews corroborated the importance of tradition (35% - 47%) and depth (88%) when starting harvesting and setting traps. Additionally, harvesters (> 40%) considered water color (likely a surrogate for turbidity) important for trap locations. Although harvesters may not be using water vii quality and chemistry data, their harvesting practices do follow water movements, likely based on accumulated experience with depth, flow velocity and turbidity.
Vargas-Lopez, Ivan A., "Crayfish Harvesting Practices in the Southern Atchafalaya River Basin: Quantitative and Qualitative Assessment of Harvester Techniques and Hydrologic Connectivity Influence on Harvesting Strategies" (2018). LSU Master's Theses. 4378.
Available for download on Thursday, January 24, 2019