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Ask DGIF: Shenandoah River Fisheries

Shenandoah RiverWe would like to thank all of our anglers and concerned citizens for their questions regarding multiple controversial issues surrounding the Shenandoah River watershed. We received many respectable and well-thought-out questions. To organize a response to these questions, we’ve split this response into three sections: Law Enforcement, Fish Health, and Fishing Opportunities and Regulations. We hope our response addresses each of the individual questions presented.

Law Enforcement

Question: Anglers and canoeist concerned with illegal harvest, littering, picnicking at access sites, unethical boat driving, and other illegal activities.

Answer: Multiple reports of illegal activities on the river and along the river banks, including at multiple access sites maintained by VDGIF, were reported. Our VDGIF Law Enforcement Officers welcome these responses as it gives them locations to focus their patrols to reduce criminal actions. If you witness any illegal activity on the river, or pertaining to other wildlife activities, it serves our Conservation Police Officers best to contact the VDGIF Wildlife Crime Line at 1-800-237-5712 or email as soon as safely possible. Although our Officers may not always respond immediately, the faster they are notified the more efficient they are at stopping illegal activities.

IF YOU ENCOUNTER AN EMERGENCY SITUATION, contact the local sheriff’s office or police department immediately and call the VDGIF Wildlife Crime Line at 1-800-237-5712. Local police departments can assist in emergency situations and also occasionally patrol river access sites.

Fish Health

Question: Why doesn’t VDGIF know what is causing the fish kills yet? Why is it taking so long?

Answer: The VDGIF has been coordinating with other state and federal agencies, universities, local volunteer groups and many other organizations to determine the causes of these fish mortality events over the last decade. The questions regarding the funds and time invested certainly warrant a proper response. Since 2004, VDGIF and partners have strived to focus on a single variable, chemical, pathogen, or parasite resulting in these mortality events. Many natural and manmade variables could be acting individually or collectively to cause these events. A study by JMU indicated possible natural variables including a change in flow or temperature patterns over time may have slightly altered the spawning periods of smallmouth bass and redbreast sunfish. This could make them more vulnerable to contaminants that may be in the river during this slightly earlier spawning time. Natural variables include but are not limited to: cyanobacteria (blue green algae) presence, water temperature pattern, flow pattern (winter/spring flows particularly), amount of direct sunlight, pathogens, bacteria and population density and size structure. Additionally some natural variables, such as temperature or sunlight, can influence the abundance of pathogens or bacteria.

Question: Why doesn’t VDGIF think agriculture is contributing to the problem?

Answer: The VDGIF recognizes agricultural practices in the Shenandoah Valley are having an adverse impact on water quality in our rivers. To date the majority of agriculture impact seems to be nutrient input in the forms of nitrogen and phosphorus, which increase the rate of eutrophication (the result of an oversupply of nutrients in a river). Eutrophication can eventually result in lower dissolved oxygen (DO) levels, increased bacteria levels and ultimately be detrimental to aquatic species. The severe version of this is more often found in small ponds and reservoirs, but certainly has an impact on river systems as well. Runoff from crop and heavily grazed fields has been found to introduce sediments that may be bound to compounds detrimental to aquatic life. A heavy load of sediments can negatively impact the ability for fish to successfully spawn. VDGIF strives to work with local Soil and Water Conservation Districts, Department of Environmental Quality, Friends of the River organizations and other conservation groups to inform the agricultural industry of these detrimental impacts to others that utilize the river downstream. We also work with these organizations and local municipalities to manage storm water runoff from urbanized areas and strongly support soil test in agricultural and residential areas before applying fertilizers. A major aid in cleaning our river systems would be the development of healthy riparian buffers.

Question: What is causing the crossing of sexes (intersex)?

Answer: Additional concerns from agricultural activities include the input of estrogenic materials from runoff that may be causing intersex (crossing of sexes). However, intersex is found in many species and this condition has yet to be linked directly to agricultural or human impacts. Wastewater treatment plants have also been noted as a contributor for estrogenic material. A good summary by the U.S. Fish and Wildlife Service of past and ongoing research on fish intersex can be found on the USFWS website (PDF). A major concern with a high concentration of estrogenic material is a possibly influence on the endocrine system of aquatic species during their development. However, there is yet to be definite proof that they are impacting development.

Question: What is the origin of Aeromonas salmonicide? Has it been monitored? Could it have come from trout that may have come from an infected water?

Answer: A pathogenic bacterium known as Aeromonas salmonicida has been considered to be a culprit of fish mortality in the Shenandoah River in recent years. This bacterium is present globally and since this bacterium has not been monitored overtime it may have been in the Shenandoah watershed historically. There were concerns that the bacterium originated from one of the state trout hatcheries, yet trout from this hatchery have been stocked in various waters statewide and have not caused A. salmonicida outbreaks on smallmouth bass and redbreast sunfish. This pathogenic bacterium is very potent and typically only impacts salmonid (trout) species, but has been documented to cause disease and mortality in multiple warmwater species even in marine environments. This leads us to believe that something else may be impacting the fish population, or the fish immune system, at the same time that A. salmonicida is thriving, which is during the springtime when these fish kills have taken place. Although A. salmonicida is a very virulent bacterium there are various other pathogenic bacteria present in the river throughout the year that do not influence fish health to a measurable level. This past research is now allowing us to look at additional variables that may be impacting the immune system while A. salmonicida is infecting the fish. This is much like humans. When we are tired and put in an environment that stresses our system we are more likely to catch a cold.

To understand the complexity of possible variables surrounding this issue you may want to refer to a report published by the Friends of the North Fork Shenandoah River (FNFSR). This report outlines the presence of manmade organic chemicals present in our rivers. In summary of the chemicals that were tested for they found 59 manmade organic chemicals originating from both agricultural and urbanized land uses. The chemicals included pesticides, polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), pharmaceuticals, hormones, and caffeine to name a few. If resources were not limited we could have a scientist investigating the spatial distribution of these chemicals, seasonal concentration of each of these, how they interact with natural variables and determine the lethal toxicity to smallmouth bass and redbreast sunfish. Unfortunately, we do not have the personnel resources or funding to complete such a task. The Friends of the North Fork Shenandoah River report can be found here (PDF).

Question: Has VDGIF looked at chemicals used to treat GMO corn?

Answer: One of the organic chemicals present in the FNFSR study that may raise concern is atrazine. This chemical is typically used on GMO corn. Although most studies indicate that there is no impact on fish and aquatic life there has been one study that illustrated a reduction in egg development in fathead minnows at or slightly below regulated levels. However, two of the four fish kill years in the last ten years yielded the highest reproduction success in the last eighteen years. Therefore it is difficult to make the same claim for smallmouth bass. This stressor has not been eliminated from the possible causes at this point.

As mentioned earlier, eutrophication has the tendency to increase the concentration of bacteria present in the water column. This may lead to an increase in bacteria or an increase in cyanobacteria (blue green algae). Cyanobacteria blooms are typically thought of in nonmoving systems such as lakes and ponds. These bacteria are also capable of forming mats on the bottoms of the rivers. When disturbed or dying the cell wall of these bacteria may burst and release toxins into the water column. If there are enough of these toxins being released at the same time it could degrade the immune system of fish rendering them vulnerable to other stressors and bacteria. Recent research has indicated an increase in cyanobacteria in waterways around the US. Investigating the presence blue green algae in the rivers and seasonal abundance may lead to further knowledge on these mortality events.

With multiple environment, agricultural and urban variables it has taken time to try to determine the exact cause or causes of these mortality events. If resources were unlimited we could have one scientist focusing on each variable that may be lethal to smallmouth bass and redbreast sunfish in the Shenandoah River and its tributaries. Unfortunately, resources are limited. To maximize our resources VDGIF and partners analyze each research project that has been completed then meticulously design the next to get the “biggest bang for our buck” so to speak. This is the fastest and most efficient approach we can take to solving this chronic issue. With a few possible causes already examined we are trying to move toward investigating how one variable may be working with other variables to cause the perfect mix that result in these spring time mortality events. Given these events are not annual, but sporadic, it complicates the process even further.

Fishing Opportunities and Regulations

Question: The past three or four years, bass have been very healthy. What happened last year?

Answer: The South Fork, North Fork and Mainstem were all impacted by the 2014 fish mortality event. It seems the North Fork may not have gotten hit as hard, but reports on the North Fork do suggest that fish greater than 11 inches declined last spring. Many of the comments received suggested that fishing success the three to four years before 2014 was significantly better than previous years and much better than 2014. Based on VDGIF sampling data this is true. Our samples indicated that 2011, 2012 and particularly 2013 were the best fishing years in the last 18 years. So from an anglers view when the fish mortality event occurred in the spring of 2014 it may have seemed somewhat intensified over the mid 2000 fish kills.

Question: Is the sand or brine from treating the roads having an impact on the river?

Answer: The recent winters have been fairly snow heavy and the question of how salt runoff from roads impacts aquatic life is often raised. According to a few studies the application of salts for snow melt does temporarily raise the salinity in local stream and possibly lakes. Depending on the road density in your area this may or may not be detrimental to aquatic life. The salinity levels from road salts in the Shenandoah Valley are generally not high enough to cause fish mortality, but may be impacting other aquatic life. Read more in this Smithsonian Magazine article.

Question: I’d like to know about musky fishing in the Shenandoah.

Answer: Musky fishing in the Shenandoah River is gaining popularity. The VDGIF annually stocks fingerling-size musky at 10+ sites on the South Fork Shenandoah. We have recently been surveying musky in the winter to determine growth rates, mortality rates and movement. Biologists have been targeting musky using electrofishing and have revealed a larger population than VDGIF once realized. Current monitoring of the musky population is ongoing to determine what size limits and harvest limits should be established. These regulations will most likely be updated in the coming years.

Question: Are the slot limits going to change on the river?

Answer: Other regulations of concern included the slot limit on smallmouth bass at specific locations and throughout the river. We sample our smallmouth bass population annually ever fall to determine population size structure and catchrate (number of fish collected/hour of sampling) which allow us to determine what regulations to set. The data we don’t get annually is creel data which allows us to determine total harvest and what size fish are being harvested. Creel surveys are conducted on average about every 5 to 6 years on the Shenandoah River system. Once we determine the harvest we are better able to set size limit and harvest limits. The last creel survey conducted documented 90+ percent of the anglers catch and release when smallmouth bass fishing. Therefore, the slot limits in place don’t really influence the size structure of the smallmouth bass population. They do however offer a conservative approach to protect the population if harvest were to dramatically increase between our creel surveys. Adjusting the slot limits is never off the table. We just like to have the scientific data to back our decisions.

Question: Are there any areas that are not impacted by the pollution/chemicals where the fish may still be safe to eat?

Answer: Anglers concerned about fish consumption issues in the rivers and surrounding reservoirs they can review the fish consumption advisory released by the Virginia Department of Health.

Question: Are largemouth bass impacted by the fish kills?

Answer: Largemouth bass are impacted by the mortality events as well. They typically aren’t impacted as heavily. Other species also exhibit lesions during the mortality events, but smallmouth bass and redbreast sunfish are the most heavily impacted. These populations fluctuate naturally as well depending on spawning success four to six years earlier.

Question: The grass seems to be impacted as well?

Answer: The VDGIF is not currently monitoring vegetation in the river. We have historically focused on the fish community as an indicator to river health. There has been concerns regarding vegetation and algae in the river and there are groups starting to monitor each. The VDGIF doesn’t currently spray vegetation on the river.

Question: Will VDGIF consider stocking another gamefish in the North Fork Shenandoah River?

Answer: Currently the North Fork Shenandoah River has largemouth and smallmouth bass. The VDGIF annually stocks 10 – 12 inch musky in the river to increase fishing opportunities. All aquatic systems, rivers and lakes, only produce a certain level of productivity and therefore limited forage fish (minnow/sunfish for big fish to eat). Stocking additional predators in the river may potentially deplete the forage fish populations, which would then lead to less food for all predators reducing angler catchrates. Currently we are not planning to add additional predators to the North Fork Shenandoah River.

  • March 2, 2015