Elusive Potomac River Muskie, Dubbed Fish 691, Caught for First Time After Years of DNR Study

Angler Garrett Davis of Clear Spring landed a 16-year-old tagged muskie in January 2026 that has been studied by Maryland Department of Natural Resources (DNR) biologists for more than a decade. Photo courtesy Garrett Davis, used with permission by Maryland DNR.

Earlier this month, Maryland angler Garrett Davis made an incredible catch on the non-tidal Potomac River. 

Davis, of Clear Spring, landed a 16-year-old tagged muskie that has been studied by Maryland Department of Natural Resources (DNR) biologists for more than a decade. This particular fish has been recaptured in surveys several times, but had never been caught and reported to DNR by an angler. 

This is the story of Fish 691, a female muskie that has been closely tracked by DNR since 2013. It’s a tale that highlights the elusiveness of prized muskellunge, or muskies, which are voracious apex predators that exist in low densities across their range in the United States and Canada. Muskies are known as “the fish of 10,000 casts” due to their hard-to-catch reputation.

The species attracts many of the most dedicated and driven anglers. Maryland manages one “true” muskie population in the non-tidal Potomac River, which supports a naturally reproducing, self-sustaining, and popular recreational fishery.  

Due to this popular sport fishery, DNR Biologists have been tracking muskies in the Potomac since the late 1990s. They do so by inserting individually numbered external dart tags into captured fish to monitor growth, movement, and estimate exploitation–or if fish are being removed at a faster rate than they can reproduce. To protect this sensitive population, DNR recommends avoiding fishing for muskies when water temperatures meet or exceed 80 degrees.

An individually numbered external dart tag on a Potomac River muskie. Maryland DNR photo

To date, DNR has tagged 1,011 muskies in the Potomac, and 466 have been reported recaptured for a 46% recapture rate. From 2017 to 2021, biologists also conducted a radio-telemetry study to better understand seasonal movements and habitat preferences.

Over the years, anglers have provided recapture data on tagged fish that paint a picture of that individual fish’s life, with some telling a more interesting story than others. When Davis reported his recent catch, it highlighted the evasiveness, longevity, and resilience of a riverine muskie in the southern part of their range.

The first capture and first recapture

DNR Freshwater Fisheries biologists annually monitor the Potomac River’s muskie fishery from Seneca in Montgomery County to Cumberland in Allegany County. During a routine electrofishing survey in March 2013, biologists collected and inserted tag 2414 into a female muskie measuring 30.25 inches. This was DNR’s first encounter with the muskie that would later be dubbed Fish 691. Exactly two years later, in March 2015, this muskie was recaptured for the first time during another routine electrofishing survey in the same general area, where she measured 36.5 inches.

Second recapture

Biologists anesthetize a muskellunge using electronarcosis and surgically implanted a radio transmitter that allowed them to monitor her movements throughout the summer and fall of 2017.

In March of 2017, biologists began implanting radio transmitters into muskies. Tag 2414 was collected during this effort, marking her second recapture by scientists. She measured 39.75 inches, weighed 15.5 pounds, and was aged at 7 years using a cross-section of her anal fin ray. 

Biologists anesthetized her using electronarcosis and surgically implanted a radio transmitter that allowed them to monitor her movements throughout the summer and fall of 2017. At the time, they dubbed her fish 950. 

Tracking data throughout 2017 revealed this particular muskie was rather sedentary. She had a distinct home range and rarely moved out of the “pool” habitat where she resided. When transmitter batteries expired in winter 2017-18, the fish went undetected again. 

Third recapture

In 2018 and 2021, grant money through Muskies Inc. was awarded to DNR to continue investigating summer habitat occupancy of muskies in waters that exceed their temperature tolerance. Staff purchased larger radio transmitters with an increased range of detection and longer battery life. 

On March 9, 2021, biologists recaptured fish 950 for the third time. Now 11 years old, she measured 43.75 inches and weighed 20.75 pounds. Biologists replaced the existing transmitter with another unique radio frequency – she now became Fish 691.  

Fish 691 was tracked weekly throughout 2021 and provided valuable data, exhibiting similar behavior with a relatively small home range and minimal movements through the duration of the telemetry project.    

In addition to annual electrofishing surveys, biologists conducted a muskie population estimate in spring 2022 in the section of the river where this fish had been documented to have spent most of her life. Extensive work was done to collect and recollect as many muskies as possible to gain an accurate estimate of the current population,  but despite biologists’ growing fondness for her, Fish 691 was not recaptured in this effort. The survey indicated that there are approximately 7 to 11 adult muskies greater than 30 inches long per river mile on this stretch of the Potomac.

The area where Fish 691 was known to reside experiences some of the highest angling pressure for muskies in Maryland. Despite having a defined preferred area, Fish 691 had still not been reported by an angler since DNR started tracking her presence in the area in 2013.

Davis lands the muskie

On January 4, that changed–Fish 691 took the end of Davis’s line and he reeled her in, marking her fourth recapture. For the first time in her 16-year life, she was caught on hook and line by an angler. Davis noted her tag number and snapped a few photos before releasing this true trophy Maryland muskie.

“I was very fortunate to catch her,” said Davis. “And, it was awesome to hear the story behind her.”

For nearly 30 years, DNR’s Freshwater Fisheries Program has been tagging muskies in the Potomac River. Many dedicated muskie anglers participate by calling in tags and recording fishing trips through the voluntary creel diary program. Occasionally, fish are recaptured by an angler a second time, rarely a third, and less than a handful of the 1,011 tagged muskies have been recaptured for a fourth time and reported by anglers. 

Fish 691 illustrates the sheer elusiveness and resilience of this prized sportfish over a 16-year span in a harsh riverine environment where there are significant angling pressures, biological surveys, floods, ice jams, droughts, and summer water temperatures that can extend beyond a muskie’s ability to survive.

DNR thanks Maryland anglers who continue to protect muskies and conserve this sensitive resource by practicing catch and release, proper handling techniques, and avoiding targeting muskies when water temperatures rise above 80 degrees. Anglers interested in learning more about muskie can visit the Maryland Muskie Program webpage on the DNR website. 

Fishing licenses as well as tackle, boat, and marine fuel purchases fund DNR’s fish conservation work. Fishing licenses can be purchased online through MD Outdoors or in person at license agent locations.