John Mullican, Fisheries Biologist
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Posted on July 30, 2012 | Permalink
Potomac and Monocacy River Juvenile Fish Surveys
Location: Potomac and Monocacy River
Fisheries staff recently completed the annual Potomac River and Monocacy River juvenile surveys. A 30 foot seine is used to collect juvenile fish at 10 sites on the mainstem from PawPaw, WV downstream to Seneca. Although the survey focuses on documenting the annual abundance of young of year smallmouth bass, the abundance of other game and non-game species is recorded as well. This data can be important when looking at long-term population trends. Typically, 9 hauls are taken at each site to account for differences in habitat and the mean number of young smallmouth per haul is determined. The 2012 Potomac survey documented an “average” yearclass of smallmouth (1.8 smallmouth per haul), nearly identical the 2011 survey. Smallmouth reproduction on the Monocacy River was higher at 3.0 smallmouth per haul, the third highest index since 1997. The biggest influences on spawning success and fry survival are river flow and turbidity. The abundance of young bass has been highest during springs with moderate, relatively stable flows and lowest in springs with above average flows and flooding.
Young fish must constantly be on the lookout for predators. While conducting the juvenile survey on the Potomac we observed a large northern watersnake struggling with a yearling channel catfish. The catfish was approximately 6 inches in length.