Tuesday, December 29, 2015

Fluvial Fishes Laboratory Review of 2015, by Don Orth

Follow the wisdom of Calvin.
As New Year’s Eve approaches, I know it’s that time to consider New Year resolutions, but resolution making is no fun.   As soon as I write a resolution, I set myself up for failure!

Instead of making resolutions, here I review highlights of the research activities of the Fluvial Fishes Laboratory for 2015. 

It is a diverse collection of papers, including  a synthesis on the Smallmouth Bass, DNA barcoding of PDUF, first record of the pughead anomaly,  human dimension of trotlining, and the Clinch Dace in the coalfields of Virginia.

For the symposium on Black Bass Diversity, Brewer and Orth (2015) wrote a summary of the Smallmouth Bass.  The Smallmouth Bass has been widely introduced in North America and is the preferred target of millions of recreational anglers.  With future projections of climate change, the range of Smallmouth Bass will show expansions and contractions.   Competitive angling, catch and release, and emerging contaminants are prevailing challenges throughout much of its range.  A person could make a career of studying the Smallmouth Bass  -- I did!

Smallmouth Bass from New River.  Photo by Paul Bugas.
You can purchase the symposium from the American Fisheries Society  click here.  

In 2013, we started a pilot study to determine if we could identify what we had been labeling as partially digested unidentified fish (PDUF) in the diets of catfish.  Zach Moran did the first test series as an undergraduate research project and we have been using the protocol from Moran et al. (2015)  every since.    The DNA barcoding approach has allowed us to identify 27 species from PDUF, including small plain-looking minnows (Hybognathus regius) and migratory species of management concern  (Alosa sapidissima, Alosa pseudoharengus, and Alosa aestivalis).

Zach Moran, currently MS student at Arkansas Tech University.

Traditional morphological approaches to identification could never provide species level identifications once the key characteristics were digested.  The success of this investigation hinged on the prior efforts of Rob Aguilar of the Smithsonian Institution to collect and archive DNA sequences for fauna of the Chesapeake Bay.  

Since 2012, Jason Emmel and Joey Schmitt have been sampling Blue Catfish from James, Pamunkey, Mattaponi, and Rappahannock Rivers of Virginia in order to describe the spatiotemporal variation in diets.  
Jason Emmel (left) and Joey Schmitt (right) have sampled over 10,000 catfishes since 2012.

Among many unanticipated findings, we began to encounter pugheaded or bulldog specimens of Blue Catfish.    Pugheadedness  (which my autocorrect wants to call pigheadedness) is a deformation of the maxilla, premaxilla, or infraorbital bones that creates a pugheaded snout and a significant underbite.  All pugheaded specimens were captured within the tidal fresh zone (0–0.5 ppt) of the Rappahannock River; no pugheaded specimens were captured in oligohaline or mesohaline waters.  Prolonged summer hypoxia may be producing these deformities in the Rapphannock River, though more research is necessary to confirm this hypothesis.
Pugheaded specimen of the Blue Catfish
Trotlining for catfish is an old tradition, and was difficult to study because trotline fishers proved very difficult to track down.  Dickinson et al. (2015) indicate that trotline fishers fish often and harvest and eat large numbers of catfish (Channel Catfish and Flathead Catfish) from the New River.  This activity that was often driven by sustenance needs earlier in their lifetimes.  Trotlining is a declining activity at a time when other pursuits, such as kayak fishing, are increasing on the New River.  This hidden fishery and the participants are among the few river users aware of the occurrence of large catfish in the New River (photo).   
Ben Dickinson with Flathead Catfish captured with trotline on New River.
In “Isolating causal pathways between flow and fish in the regulated river hierarchy,” McManamay et al. (2015) examined how river regulation affects stream fishes through reach scale changes, not always through hydrology.    The type of dam and operation has a direct influence on sediment and temperature and was most important determinant of fish assemblage characteristics. This paper was only possible by leveraging collaborative sampling efforts conducted by the Tennessee Valley Authority. 
Ryan McManamay with buffalofish.
In a symposium paper, “Legacy of dams on the New River,” we described the localized effects of the dams of the New River drainage.  One of these dams, Fries Dam, is the oldest dam on the New River and is currently undergoing the FERC relicensing process.  
Map of New River near Fries.
Historic postcard photo of Fries and New River.
You may review photos describing the Fries Hydroelectric project by clicking here.   
Fries Hydroelectric project can produce 5,213 kW of energy with hydraulic capacity of 2,100 cfs.   Structures include a 41 foot high x 610 foot long rock masonry dam.  Water is diverted into a canal to the powerhouse; after flows exceed the 2,100 cfs capacity, flows are spilled over the 500 foot spillway crest.  Storage capacity is very limited due to sediment deposits above the dam.   I wrote a long, detailed letter to the FERC regarding the environmental consequences of continued operation of the Fries Hydroelectric project.
Google Earth photo of New River above Fries Dam. Note the mid-channel island built from the trapped river sediments.  Not present in the historic postcard photo.
Clinch Dace Chrosomus sp. cf. saylori.  Photo by Isaac Szabo

 This yet-to-be-named yellow-finned minnow maintains small, fragmented populations in this rugged landscape of the coalfields of Virginia.  In November of 2015, we flew over many of these sites with Southwings and gained a better understanding of the nature of the modifications of this landscape.   Runoff over the unweathered exposed rock elevates the ionic content of the stream water, usually far beyond the tolerance of macroinvertebrates and fish.   Here are a few photos from this flight.

So I resolve in 2016 to keep doing what I did last year.  Do research and move things along.  It seems to be working just fine. 


Brewer, S. K., and D. J. Orth.  2015.   Smallmouth bass Micropterus dolomieu, Lacep├Ęde, 1802.  Pages 9-26 in Tringali et al. Black Bass Diversity: Multidisciplinary Science for Conservation. Proceedings of the Symposium Black Bass Diversity: Multidisciplinary Science for Conservation, American Fisheries Society, Bethesda, Maryland.

Dickinson, B.D., D.J. Orth, and S.L. McMullin.  2015.  Characterizing the human dimensions of a hidden fishery: riverine trotline fishers.  Fisheries 40(8):386-394.

McManamay, R.A., B.K. Peoples, D.J. Orth, C.A. Dolloff, and D.C. Matthews.  2015.  
Isolating causal pathways between flow and fish in the regulated river hierarchy.  Canadian Journal of Fisheries and Aquatic Sciences 72(11):1731-1748.   DOI: 10.1139/cjfas-2015-0227

Moran, Z., D.J. Orth, J.D. Schmitt, E.M. Hallerman, and R. Aguilar.  2015.  Effectiveness of DNA barcoding for identifying piscine prey items in stomach contents of piscivorous catfishes.  Environmental Biology of Fishes  99:171-176.   DOI 10.1007/s10641-015-0448-7

Schmitt, J.D., and D. J. Orth.  2015. First record of pughead deformity in Blue Catfish.  Transactions of the American Fisheries Society 144:1111-1116.

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