Parasites can be very influential in various aspects of aquatic health, conservation, industry, and environmental management. They can affect the size and marketability of fish, compromise wildlife conservation, and pose risks to public health. However, despite their ubiquity and significance, how human impacts on the environment affect their distribution is largely unknown. This study investigates this by creating a historical timeline for the abundance of Philometra spp. blood worms in Puget Sound, WA. In this study, I used preserved specimens of English sole from the Burke Museum Ichthyology Collection to document the presence of the parasite and make comparisons of fish caught in different regions and oceanographic regimes within the Sound. I used this data to investigate how Philometra spp. abundance tracks with implementation of restrictions on English sole exploitation. I also obtained live samples of English sole to compare the historical timeline with contemporary data. This timeline ultimately provides insight into the mechanisms of how fishing, and fishing cessation affected the distribution and abundance of Philometra in English sole.
Results/Conclusions
Results have shown that there has been an increase in parasite abundance in English sole after the cessation of fishing in the 1980s. The average abundance of Philometra from 1936-1954 was 0.33, whereas the average abundance from 1975-2016 was 1.2, a significant increase over time. Furthermore, applying the Poisson’s model to the Philometra burden, there is a predicted yearly increase of 0.04433. The results of the spatial data concluded that there is no significant spatial autocorrelation of parasite prevalence throughout Puget Sound, indicating that although there were more hosts available due to the cessation of fishing, the parasite burden was not higher in known locations of higher host density. This ultimately indicates that the mechanism of Philometra infection is not based on host availability due to fishing, but rather other anthropogenic effects, such as altered shorelines and oceanography, excess nutrient deposits, and climate change. This change in parasite abundance and its mechanisms is crucial to understand, as it can provide insight into the anthropogenic impacts imposed on the ecosystem. This knowledge will aid in the conservation of fish species, as well as determining fishing regulations and policies that in turn affect the economy and public health, making this area of study one of great value and worthy of further pursuit.