2023 Potomac River Report Card

#PotomacReportCard
Potomac Concervancy

Fish


Healthy and diverse fish populations are often indicators of a healthier watershed. A river that can support thriving populations of fish will typically have cleaner and clearer water as well as robust habitat to support them. Thanks to regional restoration efforts, the Potomac River has experienced significant improvements in the quality of its water over the past decades, which has in turn revived fish populations from historic lows.

Despite these improvements in baseline water quality across the region, some formerly well-established fish populations are facing threats that risk slowing their recovery. Striped bass populations continue to decrease across the Potomac and Chesapeake regions, requiring decision-makers to increase conservation measures across the area. Smallmouth bass have also experienced recent flux in population as high amounts of precipitation and deforestation have negatively affected local habitat and water quality. For example, when areas with few or no trees experience heavy rainfall, the land’s ability to naturally absorb rainwater is significantly weakened. A rush of stormwater and polluted runoff erodes streambanks and creates muddy waterways. Turbid and toxic water conditions degrade the underwater habitat that fish and other species depend on to survive.

Excessive pollution across the region causes an array of issues including degraded habitat, lower levels of dissolved oxygen, and an increased presence of environmental toxins like PCBs or heavy metals. Additionally, recent studies have raised red flags on emerging pollutants such as microplastics, endocrine disruptors, and many more that threaten our indigenous fish population and how people interact with them in the future.

Shad

2023 A

The American shad was once one of the most sought-after fish along the Atlantic coast, especially throughout the Chesapeake Bay watershed. However, this once great fishery experienced rapid decline through a combination of development, poor fisheries management, and degraded water quality.

Recently, concerted restoration efforts have dramatically improved shad populations throughout some parts of the Bay, especially populations in the Potomac River. Average young-of-year (YOY) shad populations from 2016 to 2020 have exceeded the 30-year historic mean by almost 300%, continuing a stretch of year-over-year improvements. Restoration efforts have included educational programs and the seeding of shad in Potomac tributaries, in addition to a commercial harvest ban that was initiated in the 1980s by both Virginia and Maryland. The District of Columbia established the American shad as its state fish in 2016, fully committing the District to the improvement of one of the most historically significant fisheries in the city.

Unfortunately, due to habitat loss and continued pollution, shad fisheries across the rest of the Chesapeake Bay and Atlantic coast have yet to improve. In order for shad populations to prosper, more work needs to be done to reduce polluted runoff into our tributaries as well as focused restoration of habitat for juvenile fish like submerged aquatic vegetation (SAV) and wetlands.

Shad - Relative Abundance

5-Year Averages (catch per haul)
Historic Mean 1985 to 2014 = 2.32
Source: Maryland Department of Natural Resources

Striped Bass

2023 C+

Striped bass continue to struggle in the Potomac River, and the Chesapeake Bay as a whole. In 2020, the juvenile young-of-year (YOY) catch per haul decreased by almost 20 percent since our last report in 2018; juvenile bass were found to be 55 percent of the 30-year average for the Potomac.

In the spring of 2020, the Atlantic States Marine Fisheries Commission (ASMFC) enacted new conservation measures in an effort to reduce harvesting and stabilize the population. Despite these measures, striped bass still make for popular recreational fishing targets across the watershed and are widely sought after throughout the Potomac and the Bay. But legacy toxins found in certain locations have made the fish unsafe to eat in some areas of the watershed, like the District of Columbia. Fortunately, according to the Maryland Department of Natural Resources, striped bass populations across the bay are primed to recover if suitable environmental conditions are met, highlighting the urgency in meeting 2025 watershed goals.

Striped Bass - Relative Abundance

5-Year Averages (catch per haul)
Historic Mean 1985 to 2014 = 4.2
Source: Maryland Department of Natural Resources

White Perch

2023 B+

White perch are an essential species to the Chesapeake Bay and the Potomac River, with almost every primary Chesapeake tributary having its own population of resident white perch. Unfortunately, white perch abundance was down 34% in the Potomac in 2020 compared to the historic 30-year average. The good news is that the five-year average abundance is still 75% of historic averages due to a strong resurgence in the Potomac white perch numbers during 2018.

Yearly fluctuations in abundances have been seen for years, but a close eye should be kept on these numbers as increased precipitation, polluted runoff, and competition from invasive species can pose hazards to future white perch populations.

White Perch - Relative Abundance

5-Year Averages (catch per haul)
Historic Mean 1985 to 2014 = 6.41
Souorce: Maryland Department of Natural Resources

Smallmouth Bass

2023 D

Smallmouth bass are an excellent indicator of stream and river health as they require cool, clear, oxygen-rich waters in order to flourish. Five years ago, smallmouth bass populations in the Potomac watershed were recorded as under 50 percent of historic averages. These populations have slowly increased over the past few years with the 2020 young-of-year (YOY) abundances reaching a five-year high of 56 percent of the 30-year historical average.

Threats to smallmouth are only increasing as sprawl encroaches into sensitive smallmouth habitat in the headwaters. Healthy forests are critical for stream health. Trees filter pollution, stabilize streambanks, provide shade for cool waters, absorb excess rainwater, and provide an important food source for stream critters through their fallen leaves. Additionally, the continued presence of invasive species and heavy spring precipitation totals are major threats.

Smallmouth populations haven’t met or exceeded the 30-year historical average in the Potomac region since 2007, proving that more work is needed to improve fish habitat and water quality throughout the area. Continuing to meet sediment reduction goals established by the EPA Chesapeake Bay Program and increasing the acreage and restoration of underwater grasses and wetlands should be a priority moving into the future.

Smallmouth Bass - Relative Abundance

5-Year Averages (catch per haul)
Historic Mean 1985 to 2014 = 1.75
Source: Maryland Department of Natural Resources

Blue Catfish

2023 n/a

Introduced into select Virginia tributaries to the Chesapeake Bay in the 1970s, blue catfish have posed a consistent invasive threat to Potomac River fisheries for decades. A popular target of local anglers, blue catfish populations have thrived throughout the Chesapeake region, preferring fresh to slightly salty water, making a large portion of the mainstem Potomac ideal habitat for these fish. With voracious appetites and few to no native predators blue catfish have become such an issue that the Chesapeake Bay program started implementing a management strategy for the invasive species in 2012.

Commercial harvest numbers have continued to grow year after year, except in the year 2020 that marked an anomalously low year due to impacts from the COVID-19 pandemic. The good news is that markets for these fish have increased in Maryland and Virginia over the past few years with commercial anglers informally stating that blue catfish have been trickier to find over the past few years. These factors have contributed to a noticeable slowdown in annual commercial harvest numbers, with the Potomac River Fisheries Commission noting a plateau of around 2.5 million pounds over the past few years. This plateau could tentatively indicate that mitigation measures in the mainstem Potomac are having some effect on population numbers, slowing their growth throughout the region.

Commercial Landings from the Mainstem Potomac (thousands of pounds)

Blue Catfish
Source: Potomac River Fisheries Commission

Snakehead

2023 n/a

Northern snakehead have been spreading throughout the region since 2002, with populations growing due to their invasive nature and lack of predators. They’ve even spread into headwater areas of Virginia and Maryland past Great Falls, which was thought to be a natural barrier to their expansion. Both Virginia and Maryland conduct annual surveys each year to assess snakehead populations and gauge their expansion and abundance throughout the watershed. To date, some studies and recent data indicate that populations may be stabilizing despite an apparent expansion of their territory.

Snakeheads should be continually monitored throughout the Potomac River region as they often pose a threat to native fish species like smallmouth bass and shad. Recent strategies implemented to reduce populations include targeted snakehead fishing tournaments as well as demand from local chefs for their sought-after meat driving the targeting of the species by anglers. It will be a few years before a true assessment on population fluctuations can be determined since their introduction to the region can be conducted but generally it seems that areas with a high abundance of public access points have seen small declines in populations while harder to reach areas have not.

Northern Snakehead: Relative Abundance in the Potomac,
Mean catch rate (fish per hour)

Northern Snakehead
Source: Maryland Department of Natural Resources and Virginia Department of Game and Inland Fisheries

Resources and Methodology

The assessment of key Potomac River fish species is an excellent way to discern overall water quality trends as most native species need clean and clear water in order to have thriving populations. To assess overall fish health we include historic and year-after-year data on common game fish including American shad, striped bass, smallmouth bass, and white perch.

Young-of-year (YOY) juvenile fish were used to assess population change among striped bass, white perch, smallmouth bass, and American shad while relative abundance and total commercial landings (lbs.) were used for invasive species northern snakehead and blue catfish, respectively. Many factors such as annual precipitation, weather fluctuations, and other environmental conditions can affect year-over-year changes in populations which is why this report looks at year-over-year changes and how they compare to long-term trends.

Specific restoration goals for these fish species don’t currently exist for the Potomac River, so grades were calculated by comparing the most recent five-year average YOY survey to a 30-year historic mean. Data was provided by Maryland Department of Natural Resources (MDNR), Virginia Department of Wildlife Resources (VADWR), and the Potomac River Fisheries Commission (PRFC).