Characterizing Louisiana\u27s Freshwater Commercial Fisheries

As an important contributor to Louisiana’s economy, the commercial freshwater fisheries have been the subject of growing attention in recent years by resource managers. Compared to the marine sector, little is known about these fisheries. Anecdotally, the fisheries appear to be on the brink of collapse. Fewer young fishermen are entering the field, fish buyers and processors are closing, and market prices remain stagnant. Because of this, the fisheries lack the resources needed to perpetuate the success and sustainability for future generations. To better understand this industry, I conducted a two-part study to characterize the commercial freshwater fisheries in Louisiana. First, I used spatial analysis to understand trends of historical landings data and fishing effort from the years 2000-2016. I mapped freshwater commercial fish landings and locations of fish houses and processors across the 12 river basins in Louisiana. Secondly, I completed in-person surveys to collect data about the fishermen, including target species, gear type, and number of trips. I also assessed their opinions and attitudes about the effect of ecological factors, commercial regulations, and human interference on their fishing success, as well as their interest in learning new techniques to improve the quality of their product. Results showed that the Atchafalaya River Basin is the preferred river basin for freshwater commercial fishermen. For 17 consecutive years, the largest number of pounds of both finfish and wild crawfish were landed within the Atchafalaya River Basin. Additionally, the majority of freshwater fish dealer license holders were located in central and southeastern Louisiana, close to the Atchafalaya River Basin region. Survey results suggested that the closing of fish houses has created a bottleneck effect for fishermen who are looking for places to sell their catch. This increases competition between fishermen, floods the market, and costs the fishermen time and money. Additionally, results showed there is an overpopulation of Asian carp (Hypophthalmichthys spp.) and alligators (Alligator mississippiensis), which can hinder the number of landings brought in. Catfish (Ictaluridae spp.) and buffalo (Ictobius spp.) appear to be the most sought-after finfish; however, this slightly differs by region. Overall, this thesis provides in-depth insight into the current trends, problems, and successes of Louisiana’s freshwater commercial fisheries. The results herein may inform future workshops, educational material, and policy actions aimed to improve the livelihood of the fishermen and success of the fisheries

“Examining How the MAFB Transcription Factor Affects Islet β Cell Function Postnatally”

The sustained expression of the MAFB transcription factor in human islet β-cells represents a distinct difference in mice. Moreover, mRNA expression of closely related and islet β-cell-enriched MAFA does not peak in humans until after 9 years of age. We show that the MAFA protein also is weakly produced within the juvenile human islet β-cell population and that MafB expression is postnatally restricted in mouse β-cells by de novo DNA methylation. To gain insight into how MAFB affects human β-cells, we developed a mouse model to ectopically express MafB in adult mouse β-cells using MafA transcriptional control sequences. Coexpression of MafB with MafA had no overt impact on mouse β-cells, suggesting that the human adult β-cell MAFA/MAFB heterodimer is functionally equivalent to the mouse MafA homodimer. However, MafB alone was unable to rescue the islet β-cell defects in a mouse mutant lacking MafA in β-cells. Of note, transgenic production of MafB in β-cells elevated tryptophan hydroxylase 1 mRNA production during pregnancy, which drives the serotonin biosynthesis critical for adaptive maternal β-cell responses. Together, these studies provide novel insight into the role of MAFB in human islet β-cells