Brook trout (Salvelinus fontinalis) belong to the salmonid family with salmon, trout, and charr. Despite their common name, brook trout are a charr and are closely related to lake trout and bull trout. Brook trout are known for their striking color pattern that includes long, worm-like vermiculation patterns on a darker background on the dorsal side of the fish, and both light, cream-colored spots and red spots with a slight blue halo along the sides of the fish. Ventral color patterns vary, but males develop bright shades of red, orange, and yellow in advance of spawning activities. The pectoral, pelvic, and anal fins have a unique color pattern that includes a white leading margin followed by a black streak, before turning a reddish orange.           

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Brook trout have strict habitat requirements that include:          

• Cold water consistently below 68°F
• Well-oxygenated streams
• Relatively stable stream bed with little sediment transport.

They become stressed when stream water temperatures exceed 68°F and may become locally extinct (extirpated) if temperatures are consistently above that threshold. Streams with considerable sedimentation may limit the reproductive success of brook trout. Silts and other fine particulates settle in the spaces between the small rocks and gravel that​ are used for trout redds (nests). This prevents the water exchange that is needed to keep eggs and fry alive by replenishing oxygen and removing waste.          

These habitat requirements generally limit brook trout to well-forested watersheds with little human development. Streams with complex habitat features such as boulders, undercut banks, and downed trees tend to provide optimal habitat. These features provide cover from predators, shade for cooler stream temperatures, and slower water flows that require less energy for swimming.          

          

Brook Trout Historically
Brook trout are unique due to their status as Maryland’s only native trout and as a key indicator and charismatic representative of coldwater habitat. Brook trout have inhabited Maryland’s freshwater streams since the glacial recession that occurred at the close of the last ice age. They have been both targeted and revered by indigenous peoples, colonists, and modern anglers.           

Brook Trout Today
Today, many residents in central and western Maryland share a watershed with brook trout, even if they aren’t present in their neighborhood stream. In many cases, residents in more urban and suburban parts of the state can find brook trout in the headwaters of their watershed, such as Gunpowder Falls and Potomac River. This fish connects us both to the past and to other communities throughout our watershed.           

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Brook trout populations throughout the state are experiencing habitat loss due to changing land use practices, climate change, and other challenges. A survey of all known brook trout populations conducted from 2014 to 2018 documented a 27 percent decline in stream occupancy statewide when compared to survey data collected as far back as the 1980s. These declines were more severe in the Piedmont geographic region of the state (Carroll, Baltimore, and Harford counties), where 50 percent of once occupied streams no longer supported brook trout populations.          

Brook trout occupied stream catchments in Maryland. Historical survey data since the 1980s have documented brook trout in the shaded catchments. Recent surveys have observed brook trout in the currently occupied catchments (black), but populations in the un-occupied catchments (red) are believed to be locally extinct.

These declines have led to renewed efforts to conserve the species. Brook trout conservation is a priority for the department to ensure that current and future anglers can continue to enjoy this resource.          

To guide brook trout conservation, Maryland DNR:          

• Has a fisheries management plan
• Lists brook trout as a species of greatest conservation need in the Maryland State Wildlife Action Plan.
• Commits to brook trout outcomes that are included in the Chesapeake Bay Watershed Agreement..
• Tasks Maryland’s fisheries managers with protecting existing populations while pursuing projects to expand occupancy in available coldwater habitat.

          

Brook trout populations face many challenges that threaten their continued occupancy throughout Maryland. Human land development can impact the waters where brook trout live and cause them to become inhospitable to these sensitive fish. It is estimated that brook trout populations will not survive when human land use in a watershed exceeds 18 percent.      

Rising Water Temperature
Loss of forest land and riparian buff​ers and increases in impervious surfaces in watersheds that support brook trout can lead to elevated stream temperatures and degraded water quality. When rain falls directly onto warm paved surfaces, heats up, and flows directly into streams without the natural buffer of trees and plants to slow and cool it down, it can create stressful conditions for trout.      

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The removal of the riparian buffer of this stream will lead to elevated water temperatures that will be stressful for the resident brook trout population.

Sedimentation
Sediment and silt mobilized from developed land and poorly stabilized soils may settle out in trout redds (nests), which can smother eggs and fry.          

Channelized brook trout stream that has been stripped of aquatic habitat. The banks are not stabilized and will contribute sediment to the stream through erosion.

Fragmentation and Barriers
Brook trout populations can become fragmented through physical, biological, and water quality barriers. Many brook trout populations are isolated in streams and are disconnected from other brook trout populations by downstream barriers. This reduces available habitat and prevents the exchange of genetic material between populations, leading to a loss of genetic diversity. Isolated populations are much more vulnerable to catastrophic events such as drought conditions, high summer temperatures, or the introduction of contaminants. Examples of barriers include dams and perched culverts (physical), stream segments with elevated temperatures or acidic pH (water quality), or competition with other trout species (biological).      

Perched culvert that limits passage in Folly Run for brook trout and other fish species.


Remnant dam in Wolf Den Run that acts as a barrier for fish passage.

Acidification
In some areas of the state, acidification caused by acid mine drainage or atmospheric deposition may limit brook trout occupancy. The pH of streams affected by acidification may reach levels that are not suitable for supporting aquatic life. These conditions frequently occur near abandoned coal mine sites that continue to discharge contaminated mine water.      

Acid mine drainage seep in a watershed that is pH impaired.​       

Maryland takes several approaches to protect and expand brook trout resources throughout the state.​      

Protecting Habitat Through Collaboration

Many of the challenges to brook trout conservation fall outside of the department’s regulatory authority, such as land use planning and the establishment and application of water quality criteria. To address this, the department collaborates with other state and local government agencies to reduce threats to brook trout occupancy. The department communicates the location of brook trout populations through resources like the Coldwater Resources Mapping Tool​ and makes recommendations for projects that are planned in brook trout watersheds to minimize potential impacts to the resource.​
            

Before and after pictures of a culvert removal project in Wolf Den Run. The Garrett County government, Trout Unlimited, U.S. Fish and Wildlife Service, and Maryland DNR collaborated to remove the culverts and replace them with a bridge that improved both the local road infrastructure and fish passage.

Identifying Projects That Benefit People and Brook Trout

The department continues to work with partners to identify projects that have co-benefits that include habitat improvement and protection for brook trout. For example, perched culverts where roads cross streams provide opportunities for the department to work with local governments towards mutually beneficial outcomes. The replacement of these culverts with bridges both improves fish passage and reconnects fish populations while also increasing the resilience of local road infrastructure to floods and other environmental hazards.            

Establishing New Brook Trout Populations

The department has several projects in progress that seek to establish new populations of brook trout in streams that have suitable coldwater habitat but do not have any existing trout populations. These projects translocate a small number of brook trout by removing them from a stable population and releasing them to the receiving stream.The hope is that these relocated fish will occupy and utilize the habitat in the receiving stream and eventually develop into a self-sustaining population. Additionally, the department is collecting wild brook trout eggs and is attempting to raise wild brook trout in an isolation hatchery for release to unoccupied streams.             

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There are many ways to get involved with brook trout conservation, ranging from simple changes in angling practices to more active roles in watershed protection efforts.      

Anglers

Brook trout conservation starts with some simple changes to a​​​ngling practices:
      

Check Water Temperature before Fishing

• Consider water temperatures and the department’s recommendations for fishing in warmer temperatures. 
• As temperatures get warmer, conditions become stressful for brook trout.
• ​Avoid fishing for brook trout when water temperatures exceed 68°F. Catching trout at these temperatures can be lethal for fish.
• Minimize handling and keep the fish in the water as much as possible when water temperatures are between 65 and 67°F.
• Water temperatures below 65°​F are optimal for trout fishing. Handle with care and return them to the water as soon as possible.
  

Handle With Care

• Use rubberized landing nets
• Handle fish only with wet hands.
• Avoid using cloth.
• Fish have a mucus layer that provides an important layer of protection. Handling with dry hands or cloth can remove that layer.
  

Use Hooks Carefully

• Remove hooks as quickly as possible and minimize injuries to the fish.
• If possible, use forceps or pliers to improve efficiency.
• Keep fish in the water while removing the hook.
• Use barbless hooks to make hook removal easier and minimize the risk of injury to the fish.
  

Tread Lightly on Land

• Be respectful of both public and private property. Treat fishing areas as you would treat your own property and leave no trace.
  

Land owners

Degraded habitat caused by land use practices is one of the most important influences on trout resources. Removing vegetation beside streams and disturbing soil without stabilization practices can lead to elevated stream temperatures and increased stream bank erosion and sedimentation in the stream.      

Landowners in trout watersheds can help protect trout populations and other aquatic life by:      

• Maintaining or planting trees and other tall vegetation within 100 feet of streams.
• Tall vegetation near streams can provide shade to keep water temperatures cool and stabilize soil to reduce erosion. In areas where tall vegetation has been cleared, planting trees within 100 feet of streams can improve in-stream habitat and water quality. Clearing vegetation on stream banks should be avoided.
• Keep livestock out of streams.
• Minimizing warm pond discharges.
  
• ​Discharges from ponds can be a major source of warmer water in coldwater streams. Avoiding this can help maintain the cold stream temperatures that trout prefer.

Get Involved

There are many other ways to get involved with managing and protecting brook trout populations. Interested individuals can reach out to members of the Coldwater Fisheries Advisory Committee and Sport Fisheries Advisory Commission to discuss ways to improve trout fishing resources and opportunities in Maryland.​
      

The Chesapeake Bay Program guides bay watershed restoration and conservation goals for brook trout. These goals are established in the Chesapeake Bay Watershed Agreement and are coordinated by the Brook Trout Action Team.
      

Eastern Brook Trout Joint Venture offers a range wide approach towards brook trout conservation in the Eastern United States.
      

Getting involved with your local Trout Unlimited chapter or watershed association may also lead to organized projects that enhance or protect brook trout habitat.