Angler Perception and Population Dynamics of the Northern Snakehead (Channa argus) in the Potomac River & Tributaries
Angler Perception and Population Dynamics of the Northern Snakehead (Channa argus) in the Potomac River & Tributaries
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Date
2016-05
Authors
Agarwal, Isha
Amrhein, Lauren
Fitzgerald, Bobby
Golt, Skyler
Gonzalez, Zeke
Hentati, Yasmine
Kang, Brian
Mann, Yvette
Matthews, Gregory
Mills, Trevor
Advisor
Miller, Tom
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DRUM DOI
Abstract
Our research sought to address the extent to which the northern snakehead (Channa
argus), an invasive fish species, represents a threat to the Potomac River ecosystem. The
first goal of our research was to survey the perceptions and opinions of recreational
anglers on the effects of the snakehead population in the Potomac River ecosystem. To
determine angler perceptions, we created and administered 113 surveys from June –
September 2014 at recreational boat ramps along the Potomac River. Our surveys were
designed to expand information collected during previous surveys conducted by the U.S.
Fish and Wildlife Service. Our results indicated recreational anglers perceive that
abundances and catch rates of target species, specifically largemouth bass, have declined
since snakehead became established in the river.
The second goal of our research was to determine the genetic diversity and
potential of the snakehead population to expand in the Potomac River. We hypothesized
that the effective genetic population size would be much less than the census size of the
snakehead population in the Potomac River. We collected tissue samples (fin clippings)
from 79 snakehead collected in a recreational tournament held between Fort Washington
and Wilson’s Landing, MD on the Potomac River and from electrofishing sampling
conducted by the Maryland Department of Natural Resources in Pomonkey Creek, a
tributary of the Potomac River. DNA was extracted from the tissue samples and scored
for 12 microsatellite markers, which had previously been identified for Potomac River
snakehead. Microsatellite allele frequency data were recorded and analyzed in the
software programs GenAlEx and NeEstimator to estimate heterozygosity and effective
genetic population size. Resampling simulations indicated that the number of
microsatellites and the number of fish analyzed provided sufficient precision. Simulations
indicated that the effective population size estimate would expect to stabilize for samples
> 70 individual snakehead. Based on a sample of 79 fish scored for 12 microsatellites, we
calculated an Ne of 15.3 individuals. This is substantially smaller than both the sample
size and estimated population size. We conclude that genetic diversity in the snakehead
population in the Potomac River is low because the population has yet to recover from a
genetic bottleneck associated with a founder effect due to their recent introduction into
the system.