Shenandoah River- A Smallmouth River Always in Meandering Condition

Fish Kills Continue to Plague the Shenandoah

Virginia boasts some of the best Smallmouth river systems in the entire country. While many of the river systems in the region demonstrate very similar characteristics one river clearly has faced more challenges than most.

“today’s watersheds are under stress from a variety of human uses and influences, from water supply demands, waste disposal and irrigation, to hydropower, transportation and recreation. Rivers are also receptacles for materials that run off the land, including agricultural, household and industrial waste.” (Paul Bugas, Virginia Game and Inland Fisheries Department 2010)

The Shenandoah River is the largest tributary of the Potomac River and probably one of the most known for Virginians in large part because of of its geographic location and the fact that there are well known destinations in close proximity to the river system through the Shenandoah Valley that attract hundreds of thousands of visitors every year.

The Shenandoah proper is roughly 55 miles long but the river system has two forks that extend the river from the Blue Ridge and Alleghenies before meeting at Front Royal, Virginia where the river then moves in northeasterly through Virginia’s lower valley into West Virginia and ultimately meeting the Potomac River at Harpers Ferry, WV. These forks or arms are called the North Fork and South Fork.

The river has a long history and its ecosystem is such that it has played a vital role in the creation of one of the best agricultural areas in the region but this has not come without a cost. The rich soil and substrate created by the meandering river system has also attracted more and more industry in its own right stemming from the by product of a river that pushes down sediment and mass through the valley below.

Like most river systems, the Shenandoah River has many industrial plants along the its path and these have often contributed to major issues over the last hundred years for the river. Whether the 1940 pollution of the river stemming from the Rayon plant at Front Royal or historic mercury waste that impacted the entire watershed or the repeated agricultural run off from farm land spread out most of the valley floor or even the acid rain issues some fifty years ago.

The Shenandoah’s history has demonstrated that it suffers from far more potential catastrophic concerns than say the James River or the Potomac River. While those rivers typically must withstand the natural high water events or extreme flooding periodically that impact the fisheries, the Shenandoah routinely must deal with “fish kills” that are certainly at a higher rate than other regional river systems.

While the 1940 incident was reportedly severe it was not until 1977 when the Shenandoah River experienced an 80% loss of fish specie density that took the river almost a decade to recover from in terms of fish populations and caused great concern for the vitality of the river going forward. Up until that point in time there were virtually no organizations or movements of any consequence to address concerns for the river and the water quality as there are today.

Even with attention finally being given to the river system, once again the Shenandoah experienced another fish kill in 2003 which began on the North Fork and lasted about two years in which ultimately stretched into the South Fork and the Main Stem of the watershed. This kill impacted some 70% of fish specie population in the watershed and about ten years later another event happened in 2014 that hit the river though only half as much in terms of kill rates on Smallmouth and other fish species.

According to VaDWR “the most recent mortality event occurred in the spring of 2014 when a few anglers and concerned citizens reported small numbers of dead and diseased smallmouth bass in the Shenandoah River. DWR verified that there were a relatively high percentage (30%) of smallmouth bass and redbreast sunfish with lesions and other abnormalities on the South Fork Shenandoah River from Port Republic to Front Royal. DWR also sampled throughout the North Fork Shenandoah River and observed fish with the same abnormalities, but the percentage was slightly lower”

What have learned in all honesty over the last fifty years is not really enough. Many of these events that have not been tied directly to a spill or industrial waste or by byproduct have been under study for decades. We still do not really know the cause of many of the events though recent tissue samples and pathology of Smallmouth kills have pointed to an immune bacteria known as Aeromonas Salmonicida.

The bacteria is a fish killer. It thrives in cold water which is why it can be so detrimental to a river system in the early spring as the cold water comes down through the valley from the mountains. Seemingly the lower the water levels as well have a direct impact on this bacteria spreading and impacting large densities of fish throughout the river. (VaDWR photo credit):

Just last week as fish kill was reported on the Shenandoah River in the Grove Hill section of the South Fork. This section stretches between the town of Shenandoah and Newport on the river. The area has some of the deeper pools in the South Fork but is also above a dam and many have questioned whether there is a dam influence in these kills in how the dam shapes the water flow, current and levels of the section. the kill was reportedly witnessed in and around the Rt 650 bridge in Grove Hill where there is also a VGDIF public boat ramp as well.

Is the geography of the Shenandoah contributing to this events? How has the James River seemingly recovered from the industrial impacts in the Middle James that plagued its water water quality for so long but the Shenandoah still repeatedly suffers from many of the same events?

The National Park Service has recognized the impact of erosion and deposition on the watershed historically which may lend some insight potentially as to why the river may experience far more issues than others:

“Over millions of years, the Shenandoah River and its many tributaries carved out the Shenandoah Valley, picking up rock particles and other earth materials, then dropping them along the way to create wide, fertile floodplains. Because streams constantly change, the Shenandoah also developed snake-like, U-shaped, looping bends called meanders. Many of the meanders are in areas with underlying shale, a relatively soft sedimentary rock consisting primarily of hardened clay, silt, and mud.

While the processes of weathering and erosion have continually broken the hills and ridges down into particles of sediment, the Shenandoah River drainage system carried the particles downstream and deposited them throughout the Valley to create rich, fertile soils. Soils are complex mixtures of rock particles, mineral particles, water, air, and decaying organic matter, called humus, from plants and animals. The particle content of the soils in the Valley is primarily derived from sedimentary rocks like limestone, shale, siltstone, and sandstone. However, the reason the soil is so productive is because most of it is born from the fertilizer-like limestone and mixed with organic humus. These soils are deep, fertile, and well-drained, great for growing grains, hay, timber, apples, peaches, and grass for livestock. Because of the productive soil and more-than-adequate rainfall, agriculture is still the top industry in the Shenandoah Valley.”

In truth many anglers may not concern themselves with much of these things. At times events can be isolated but it only takes the stars aligning for a major disaster to beset the Shenandoah River once again. Anglers can do their part with the reporting of any observations out on the river and especially during the spawn. (VaDWR photo credit)

The Aeromonas Salmonicida bacteria creates lesions and tissue deterioration which can remove scales and thus remove a defensive barrier for the Smallmouth from other issues in the water quality. These lesions are like skin ulcers. There is no real easy means to treat a fishery succumbing to the bacteria even though Pimafix often combined with Melafix works as a skin care means there is certainly no way to treat all fish in a river system impacted by the bacteria and the costs of doing so are well lets just say insurmountable.

“Determining the cause of these mortality/disease events has proven to be extremely difficult. Scientists have and continue to conduct in-depth studies on fish health, pathogens, water quality, contaminant exposure and toxins released by bacteria (blue-green algae). Current studies are focusing on endocrine disrupters, bacterial toxins (blue-green algae), and water quality impacts. The fact that these events have occurred in multiple watersheds that differ in many ways has added to the complexity of understanding the primary cause. (VaDWR photo credit)

Fish health investigations to date have included: histopathology (Figure 2), parasitology, bacteriology, virology, and blood and liver analysis (Figure 3). This information has been collected from the affected rivers, and also from a few “reference” rivers where these mortality/disease events have not been occurring. Fish health samples have been analyzed by several Universities, the United States Fish and Wildlife Service’s Northeast Fish Health Lab, and the United States Geological Society’s Eastern Fish Health Lab. While researchers have collected a plethora of fish health data, linking the disease and mortality episodes to a single cause has been elusive. Detailed research findings are described in the Virginia Tech University final report “Investigation Into Smallmouth Bass Mortality in Virginia’s Rivers” (Orth et al. 2009) (PDF).” (VaDWR)

The result of these kills especially this time of year is a direct impact on recruitment and thus future populations in the Shenandoah River system. The bacteria can not only impact younger fish but also the older fish within the system that are already approaching 18-20 inches in length and if those classes of fish get wiped out by a major watershed event the river will be left once again with a decade long recovery starring it in the face.

The Main Stem has sustained an increase in quality Smallmouth population density over the last decade and the hope is what ever the recent fish kill situation becomes it does not spread from the South Fork throughout the entire watershed as has happened in the past. Fishing on the Shenandoah has been outstanding this season heading into May. Quite a few five and six pounders have been caught already not only from guide trips but also by individual anglers.

There is no argument that the South Fork Shenandoah gets the most fishing pressure in the Shenandoah River watershed but while the fish kill situation of 2024 unravels many guides and others may look to other areas in the river system that are every bit as productive as the South Fork.

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