Executive Review: 2019 Mid-Atlantic Smallmouth Bass Health Assessment


Thursday, 8 August 2019
Mather Training Facility, Harpers Ferry, WV

Executive Summary

Anglers, fishing guides and fisheries biologists all have noticed a precipitous decline in the number of smallmouth bass inhabiting our Mid-Atlantic rivers over the past few years. Where have these fish gone and is this just a naturally occurring cycle or an indication that something is amiss in the water itself? These were just some of the questions that were on the mind of the Shenandoah Riverkeeper Mark Frondorf and state and federal fisheries biologists as Frondorf pulled together the Mid-Atlantic Smallmouth Bass Health Assessment to investigate this matter further. This is not an idle academic exercise either as the smallmouth bass fishery and river guide industry generates close to 700 million dollars per year in the Mid-Atlantic, representing a significant economic driver in the region.

The event took place at the National Park Service Mather Training Facility in Harpers Ferry, WV on 8 August 2019. In addition to the fisheries biologists working their respective rivers, Dr. Vicki Blazer, USGS Fish Health Branch, shared her valuable insights as she has conducted research on all of the rivers in question and collaborates with many of the state fisheries biologists. Fishing guides from each of the watersheds also attended and shared their valuable insights and perspectives as they have witnessed the unfolding of this story on an almost daily basis.

Concern centered on water quality and quantity and the need for more data to better understand the issues. We produced this executive summary from notes taken during the Assessment but the reader needs to keep in mind that while the author has a STEM degree, it’s in political science, not fishery science, so for a more complete picture of the data conveyed, we suggest you peruse the slides presented at the Assessment by the biologists.

The Shenandoah, Potomac (including the Upper Potomac) and Susquehanna have witnessed the decline of the overall smallmouth bass population, with the disappearance of one to two-year-old smallmouth bass being most pronounced. Smallmouth bass are very sensitive to water quality. Are they the “canary in the coal mine” indicating a widespread water quality problem?

The fishery is delicate and directly affected by river flow levels – especially during the spawn. Six of the highest top flows over the last 100 years have occurred in the last 10 years. High water levels in May and June destroy fish nesting sites, wash away small fry and increase turbidity that negatively affects fish health. Brandon Keplinger, WV District II Fisheries Biologist, noted that fish populations could recover as long as there is not an extended period of time (four to six years) of low spawning numbers. However, with the uncertainty of climate change, the watershed could see more storms and increased flash high flows as has occurred recently. The extremely wet 2018 season affected the Upper Potomac fishery and was definitely an unusual year but some are wondering if abnormal conditions are now the new normal.

Some noted that smallmouth bass recruitment also occurs in years of extremely low river flows, particularly in May, when fish are spawning, indicating that there is a river level “sweet spot” needed for a robust spawn to occur resulting in large numbers of young-of-the-year smallmouth bass.

The prevalence of more affordable small watercraft allows increased human activity on the water. Fish react with a flight response, putting them under additional environmental stress. The
high usage from small watercraft (primarily kayaks) by anglers makes it likely that fish throughout the watershed stand a good chance of being caught in season.

Smallmouth bass populations seem to be in a recover-then-crash pattern, according to Brad Fink, VA Department of Game and Inland Fisheries. Significant fish kills began in 2000 and continued to varying degrees until 2010. No one certain cause has been determined but a connection exists when lesions occur on the fish: when 30% or more of their body has lesions, it indicates a fish kill is occurring or is on the way. The cause of fish with melanistic colorization or “blotchy bass syndrome” is unknown at this time.

Fink alerted participants that on the South Fork of the Shenandoah River over the past ten years, the South Fork has experienced five years of below-average spawns, four years of roughly average spawns and just one truly exceptional spawning class which took place in 2014. The last three years have witnessed average to below-average spawn classes. Fink said the river is capable of accommodating a few years of poor recruitment, allowing other year classes to fill in those niches, but over time, the overall population numbers will begin to fall, which is what we are seeing on the South Fork of the Shenandoah River. Fink noted that it is more difficult to get good data on the North Fork of the Shenandoah due to the smaller size of the river and the ability of VDGIF to conduct electroshocking on that reach of water.

Michael Kashiwagi, Western II Regional Fisheries Manager, shared that a spring 2019 supplemental smallmouth bass stocking effort using smallmouth bass collected by spring tournament anglers was not successful. Nonetheless, they learned quite a bit in their attempt and will consider undertaking the project in spring 2020. They undertook this unusual project because they recognized the extremely low numbers of smallmouth bass through the Potomac fishery due to almost ten years of poor spawn classes.

One piece of good news is that the population of adult smallmouth bass (defined as fish three years of age and older) still in the river, seem to be holding steady and monitoring results show that the adults are increasing in size. These fish seem to be healthy this year with no lesions or other visible signs of distress. They are also paying close attention to the fact that fish composition in the river seems to be changing in that they are seeing far fewer minnows or bait fish than normal.

Fishing guides also noted this decrease in bait fish and expressed their concerns regarding the Maryland spraying of Bacillus thuringiensis serotype israelensis (Bti) to help control black flies which some believe negatively impact smallmouth bass populations by reducing a potential food source on an already stressed juvenile smallmouth bass population. A direct link has not been determined at this time, but Dr. Vicky Blazer, USGS, agreed that we need a better understanding of the food web, as well as the pathogen/parasite relationship.

The population of invasive flathead catfish, which eats juvenile smallmouth bass, is increasing in the Potomac River. Once established, it is difficult to control the populations of this non-native species. Due to catfish tournaments, some anglers desire them in the river so are actually trying to establish them, resulting in tension between anglers and conservationists. Concern remains regarding the snakehead fish as well, another aggressive, invasive species.

Algae continues to be of concern for both the overall health of the fish, benthic populations and for recreational use of the river. Officials are making note of algae but no formal study is underway. It is difficult to assess algae as it blooms and disappears quickly and water flows and turbidity complicate the assessments. Drones captured images in order to distinguish between the types of algae but this approach has not proven to be very successful.

Geoffrey Smith, Pennsylvania Division of Fisheries Management, Susquehanna River Biologist, noted that the Susquehanna is seeing more mortality in juveniles as opposed to adults in the other rivers. Pennsylvania is attempting to standardize their testing throughout the watershed to get a better understanding of its overall health. Smith said that during the mid-2000s they saw a lot of mortality due to disease and that from 2005-2012 the Susquehanna experience high mortality of adult fish along with 7-8 years of low recruitment.

Since 2012 recruitment has improved with more 1-2-year-old fish. However, they have also had the past 3 years of variable flow. He stated the worst time to have a high flow event on the Susquehanna is in June. He asked if climate change is manifesting itself in the Mid-Atlantic with more late spring flash high flows due to warmer weather and stronger storm events. If so, this is very worrisome to the health of the smallmouth bass population. He noted that Pennsylvania has been proactive in trying to stay ahead of the situation by strengthening/relaxing fishing regulations based on monitoring data.
This year, Pennsylvania removed “closed season” during spring of 2019 season.

Smith noted that lesions are being seen on adult bass. In October 2018, biologists determined that Middle Susquehanna smallmouth bass were exhibiting lesions on about two percent of the fish while Lower Susquehanna River bass had lesions on about 23 percent of the smallmouth bass examined during their research.

Dr. Vicki Blazer, USGS Fisheries Lab, explained that one of the most complicated issues facing water quality and fish health are the myriad chemicals in the water including endocrine disruptors. These chemicals, linked to intersex abnormalities in adult fish, enter the river, since wastewater treatment plants currently do not filter them out. Dr. Blazer noted that fish respond differently to stressors and multiple chemicals can have similar effects. However, the complex mixture of chemicals in addition to environmental stressors such as nutrients, water temperature, turbidity, etc. can adversely affect fish health.

Blazer said that she has been studying smallmouth bass since 2003 and noted that there is no one cause for the fish kills seen to date but rather a perfect storm of multiple bacteria and other agents at work that collectively weaken their immunosuppression system, making them succumb. She pointed out that with young of the year smallmouth bass mortality in the Susquehanna watershed, many coinfections have been identified.

Her groundbreaking research identified that smallmouth bass’s exposure to estrogenic chemicals results in the creation of intersex fish.

Some of her Lessons Learned have included:

  • All fish are not created equal. They respond differently.
  • Aquatic organisms are exposed to complex mixtures of chemicals in addition to other environmental stressors (nutrients, temperature, etc.)
  • Multiple chemicals can have similar effects
  • Many effects such as intersex may occur early in life and not be seen until maturity.

She is now focusing much of her research on the long-term impact of these endocrine disruptors on fish health. She identified that the herbicides encountered most often include atrazine, simazine, metolochlor, fipronil, and metalyxyl. Blazer also pointed out that you have to study fish tissue since what is in the water may not provide the whole picture. Also, need to study the yolk of the egg for more data.

Her research also found that genes are being suppressed – and believes a new virus is causing the dark splotches on the fish, creating melanistic adult bass – termed “blotchy bass” syndrome. It is just odd dark tissue on the body, fins, mouth and does not appear to be precursors to the creation of lesions.

Her molecular studies work, along with the efforts of her USGS researchers, Heather Walsh, Adam Sperry, and Luke Iwanowicz, indicate they may not be looking at the right things. She noted that Metformin is one of the most commonly prescribed drugs for diabetes and was the only pharmaceutical found at all of their research sites. What role, if any, does Metformin play in impacting the smallmouth bass population.

Blazer lamented that the Chesapeake Bay Endocrine Disruption project is ending while there are still many questions that need to be answered and others that haven’t not even been asked as of yet. She believes that much more work needs to be done on how land and climate change affect fish issues and the importance of analyzing trends over time. She also believes it is critically important to assess agricultural best management practices in relation to our chemical and biological data and then to utilize this data to choose “focal sites” for more in-depth study. She closed by saying we need a better understanding of the food and parasite/pathogen web.

The Mid-Atlantic Smallmouth Bass Health Assessment seemed to raise more questions than it answered. What is the role of landscape runoff and inputs of nutrients, pesticides and wastewater? What role will climate change play in water flows and temperatures? What are the effects of streamside habitat degradation, increased impervious surface and algae to watershed health? What role do invasive species, pesticide application and increased human activity have on the watershed?

What the Assessment did answer was that the region’s rivers need more monitoring and research, more funding for additional data, more communication between local, state, and federal stakeholders and more public awareness of the issues confronting our Mid-Atlantic rivers. Finally, several of the biologists noted that it would be beneficial to set up a small working group where participants could share approaches, insights and preliminary findings and keep communication open between the state and federal biologists and researchers.