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Wednesday, February 4, 2015

Congrats to Derek Bahr

At the recent Southern Division AFS, our very own Derek Bahr was runner-up for the Best Student Presentation Award. Congrats Derek! The abstract of the talk he presented is below.

Atlantic Sturgeon recruitment in the Savannah River, Georgia

Derek L. Bahr
Warnell School of Forestry and Natural Resources–University of Georgia
180 E Green Street, Athens, GA 30602
Phone: (715) 869-0513

Douglas L. Peterson
Warnell School of Forestry and Natural Resources–University of Georgia
180 E Green Street, Athens, GA 30602
Phone: (706) 542-2944

Atlantic sturgeon were once abundant along the Atlantic Coast of North America from the Saint John River, Canada to the St. Johns River, Florida. Severe overfishing, coupled with habitat losses during the 1900s, resulted in major population declines that eventually led to the species’ listing under the US Endangered Species Act in 2012. Although Atlantic sturgeon are now considered endangered, quantified recruitment data are largely lacking for most systems, particularly among populations within the South Atlantic Distinct Population Segment (DPS). The objective of this study was to quantify annual recruitment of Atlantic sturgeon in the Savannah River, Georgia by estimating annual abundance of age-1 river-resident juveniles. During the summers of 2013–2014, we used anchored gill nets and trammel nets to sample juvenile Atlantic sturgeon throughout the Savannah River estuary. Ages of captured juveniles were determined using length-frequency histograms that were verified with fin ray cross sections from a subsample of the captured fish. Abundance of each juvenile age class was then estimated with Huggins closed-capture models in RMark. Our results showed that the Savannah River contained 528 (95% CI, 402–726) age-1 juveniles in 2013 and 616 (95% CI, 500–775) age-1 juveniles in 2014. These findings suggest that the Savannah River population is likely the 2nd largest within the South Atlantic DPS.  Future estimates of juvenile abundance should help provide quantified information regarding population trends as well as identify key environmental variables affecting recruitment in the Savannah River system.

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