Using sex ratios of Brook Trout to identify population resilience and spawning adult size

Bethany Wager*, Ross Andrew, Christopher Schwinghamer and Kyle Hartman, Division of Forestry and Natural Resources, West Virginia University, Morgantown, WV 26506

Field (Broad Category): Natural Resources/Wood Science/Plant Science (Oral-Science & Technology) 

Student’s Major: Wildlife and Fisheries Resources 

Brook Trout are the only native species of trout in West Virginia. Some Brook Trout populations may be more or less resilient to fluctuations over time and identifying drivers of their resiliency is important for conservation of these populations. Through research on 25 streams in West Virginia, we investigated sex ratios as a metric which may influence population variation and resilience over time. Defining the size of both male and female fish during the spawning period may also help determine reproductive potential within a given stream. We analyzed data from 2016-2017 and found females (153mm & 34g) to be slightly smaller than males (165mm & 41g) across sites on average. When comparing sex ratios, the expected result is that streams with a low population of females will also have higher levels of variation in population. Across sites, as the sex ratios descend from female-dominant and approach 1:1 the population numbers decrease. Furthermore, a negative trend was identified between the average female proportion of the population sample and the long-term coefficient of variation for overall Brook Trout abundance. We illustrate females as drivers of reproductive magnitude and their critical role to ensure stable population numbers and genetic variation into the future. 

Funding: West Virginia Division of Natural Resources 

Program/mechanism supporting research/creative efforts: WVU's Research Apprenticeship Program (RAP) & accompanying HONR 297-level course