Population Structure of White Perch (Morone americana) in the Delaware Bay

Shaffer, Megan
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University of Delaware
White perch (Morone americana) are one of the most common fish found in the waters of the eastern United States. In Delaware Bay, they are used to monitor contamination levels and set seafood safety consumption advisories and are therefore of ecologic and economic importance. This study sought to determine the genetic population structure of white perch in Delaware Bay. Fish were collected in the summer of 2013 from three separate locations. Five mitochondrial loci (cox2/ATP8/AT6/cox3, cyt-b, ND2, ND3/4L/4, ND5) and two nuclear loci (cx35, GH) were examined. Using PCR-RFLP analyses, polymorphisms were found in ND2, ND3/4L/4, ND5 and GH. An exact test performed on mitochondrial loci revealed no significant differentiation between the three locations, while a Fst value for GH suggested slightly significant genetic differences between the three locations (P = 0.044). A two-way ANOVA with replication for size data, genotype and location revealed that the three locations sampled contained fish of significantly different sizes (P = 0.0112) but that genotype had no significant effect on fish size nor did location and genotype interact. Mitochondrial data was combined with previous data from Gaffney lab to allow for haplotype frequencies of fish to be compared between nine locations in Delaware Bay, which were significantly different (exact test, P < 0.0001). The results suggest at least three different populations of white perch exist in Delaware Bay. White perch have been found to have an upper salinity limit and salinity gradients in Delaware Bay may prevent white perch from migrating between populations. The results of this study, in conjunction with future analyses, can allow fishery management practices to better coincide with the biology of white perch.