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Youghiogheny River Lake

Fayette & Somerset Counties
April-May, 2007
Survey Gear: Trap Nets & Night Boat Electrofishing


Youghiogheny River Lake is a 2,840-acre (at normal summer pool) impoundment with the dam located near Confluence, Pennsylvania. This waterbody serves as the boundary between southern Fayette and Somerset Counties, and part of its waters lie in northern Garrett County, Maryland. Although 590 acres (about 21%) of the lake’s surface area resides within Maryland, Pennsylvania Fish and Boat Commission Fisheries Management Area 8 biologists are responsible for developing the lake’s aquatic resource management plans through cooperative agreement with Maryland DNR. All fish harvest is guided by Statewide Regulations for Commonwealth Inland Waters.

The dam is owned and operated by the U.S. Army Corps of Engineers, and was constructed primarily for flood control purposes on the Youghiogheny River, but also for downstream water quality enhancement, flow augmentation, power generation (since 1989), and recreation. Pleasure boaters, water-skiers, jet-skiers, and anglers take advantage of the lake’s unlimited horsepower regulations, as well as five public launch ramps (Jockey Hollow, Tub Run, Somerfield North, and the Spillway Recreation Area in Pennsylvania and Mill Run in Maryland) and one private launch ramp/marina (Somerfield South in Pennsylvania).

Youghiogheny River Lake is clear and deep (maximum depth approximately 120 feet), but it is also “oligotrophic,” meaning it contains minimum nutrients. Upstream of the lake in Maryland, the Youghiogheny River watershed suffers from low buffering capacity, and as a result, the lake is easily influenced by upstream inputs of acid mine drainage and acid precipitation. Although overall lake water quality has gradually improved since construction of the dam was completed in 1943, infertility continues to limit the growth of phytoplankton and aquatic vegetation, which ultimately affects the growth rates of many of the lake’s fish species. Over the last 30 years or so, the lake’s alkalinity concentration (a measure of its buffering capacity and ability to grow fish) has remained consistently low (less than 20 parts per million).

The main purpose of our 2007 surveys was to determine the size and quality of the lake’s resident gamefish and panfish populations, including smallmouth bass, northern pike, walleye, black crappie, and others. A unique objective of this year’s investigation was also to determine the extent of survival from recent walleye stockings, as well as what percentage of the existing walleye population is a result of natural reproduction occurring within the lake. The final outcome of this year’s work will be an updated fisheries management strategy for Youghiogheny River Lake.

Walleye, as both fry and fingerlings, have been stocked in Youghiogheny River Lake annually since 2003. Walleye that were stocked during this time were marked with Oxytetracycline (OTC). This marking occurs at Commonwealth hatcheries by immersing walleye fry and/or fingerlings in an OTC solution. Oxytetracycline is normally used as a broad-spectrum antibiotic for various bacterial infections in humans. However, OTC was found to possess a unique characteristic of binding to calcium and magnesium present in calcified structures of fish. When a calcified structure of a marked fish is placed under an ultraviolet light and viewed with a fluorescent microscope, OTC markings appear as bright yellow- or chartreuse-colored rings.

The calcified structure typically examined for OTC markings is the otolith, or “earstone.” In bony fish such as walleye, three pairs of otoliths can be found directly behind the fish’s brain. Otoliths are involved in the detection of sound, gravity, and/or converting sound waves into electrical signals. Fisheries biologists frequently use thin cross-sections of otoliths to determine the age and growth of fish.

Otolith
Here is a thin cross-section of a walleye otolith marked with OTC and viewed under ultraviolet light using a fluorescent microscope. The age of this fish is estimated by counting the “annuli”, or chartreuse-colored rings, as one would count rings on a tree to determine its age. Photograph courtesy of Michael Hendricks, Research Fisheries Biologist, Pennsylvania Fish and Boat Commission.

Walleye provided the highest single species catch from our trap nets. Most of the walleye collected during our trap net surveys were legal-sized (greater than 15 inches). Since walleye otolith samples will not be processed until about December 2007, at this time we do not know the origin of collected fish; those derived from our hatcheries and marked, or those derived from natural reproduction and un-marked. We look forward to reporting those results as soon as we are able.

In addition, several nice smallmouth bass were collected from trap nets, some in the 20-inch range, as well as many sizeable channel catfish, black crappie, and a few legal northern pike. Table 1 below summarizes the catch data from our 2007 trap net surveys.

Table 1.  2007 Survey Gear: 16 Trap Net Sets.
Fish Species Number Collected Size Range (Inches) Additional Comments
Walleye 81 14 – 25 96% legal fish.
Yellow perch 1 8 – 9  
Black crappie 43 8 – 14 95% greater than 9 inches.
White crappie 3 10 – 11  
Rock bass 20 4 – 10  
Bluegill 45 2 – 10  
Pumpkinseed 5 3 – 10  
Sunfish hybrid 1 4 – 5  
Smallmouth bass 27 9 – 20 48% greater than 12 inches;
22% greater than 15 inches.
Northern pike 2 26 – 31 All legal fish.
Channel catfish 17 13 – 27  
Brown bullhead 2 14 – 15  
White sucker 5 17 – 22  
Common carp 1 31  

Catfish
Area 8 Fisheries Manager Rick Lorson with a 13-pound, 27-inch channel catfish collected from a trap net set at Youghiogheny River Lake

During our night boat electrofishing surveys, we were pleasantly surprised at the number of quality (greater than 15 inches) largemouth and smallmouth bass collected. We found the black bass population consisted of 85% smallmouths and 15% largemouths. Table 2 below summarizes the catch data from our 2007 night boat electrofishing surveys.

Table 2.  2007 Survey Gear: 9 Night Boat Electrofishing Runs.
Fish Species Number Collected Size Range (Inches) Additional Comments
Walleye 8 16 – 21 All legal fish.
Smallmouth bass 97 3 – 20 58% greater than 12 inches;
31% greater than 15 inches.
Largemouth bass 17 5 – 21 59% greater than 12 inches;
29% greater than 15 inches.
Northern pike 4 17 – 29 75% legal fish.
Chain pickerel 2 10 – 20  

Smallmouth bass
Area 8 Fisheries Biologist Bob Ventorini with two 19-inch smallmouth bass collected during night boat electrofishing surveys at Youghiogheny River Lake

Largemouth bass
Area 8 Fisheries Biologist Aid Jon Trilli with a 21-inch largemouth bass collected during night boat electrofishing surveys at Youghiogheny River Lake

Total walleye and legal length (greater than 15 inches) walleye abundance data from trap net surveys showed a generally increasing trend from 1982 through 1998 (Figure 1). However, it appears that the population has recently declined to a certain degree following annual stockings since 2002. One must bear in mind that walleye populations fluctuate in abundance from year to year in most waters in Pennsylvania, whether stocked or maintained through natural reproduction.

Figure 1

Total smallmouth bass and legal (greater than 12 inches) smallmouth bass abundance data from electrofishing surveys showed a generally increasing trend from 1982 through 1998 (Figure 2). The abundance data for total and legal length smallmouth bass declined slightly in 2007, however the abundance of quality-sized fish (greater than 15 inches) was the greatest this survey year.

Figure 2

Total largemouth bass and legal (greater than 12 inches) largemouth bass abundance data from electrofishing surveys was variable from 1982 through 2007 (Figure 3). Similar to the smallmouth bass data, the abundance of quality-sized largemouth bass (greater than 15 inches) was the greatest this survey year.

Figure 3

Our sampling in 2007 also provided the highest numbers to date for quality size channel catfish and crappies, with good numbers of bluegills and rock bass. In summary, despite historical and contemporary water quality issues related to infertility and acidification, the fishery of Youghiogheny River Lake has improved dramatically since 1943 and remains very good. Throughout the last 30 years or so, the lake has continued to provide anglers with quality fishing opportunities for gamefish species such as walleye, northern pike and channel catfish, as well as panfish species including black crappie, bluegill, perch, and rock bass. Finally, our most recent data is suggesting that Youghiogheny River Lake now provides anglers with an excellent opportunity for quality-sized largemouth and smallmouth bass.

 
-- Bob Ventorini, Area 8 Fisheries Biologist

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