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Keystone Lake
Westmoreland County
May 2009
Survey Gear: Night Electrofishing and Pennsylvania Style Trap Nets

Keystone Lake is a 78 acre impoundment located within Keystone State Park in Westmoreland County, just north of the town of Latrobe. The lake is an Stocked Trout Water. The lake is stocked with catchable rainbow trout Preseason, Inseason, Fall, and Late Winter, creating coldwater fishing opportunities in all seasons except summer. Trophy golden rainbows are also part of the stocking.

Golden rainbow
A trophy golden rainbow that was cruising the shallows around the boat launch prior to our survey

Keystone Lake contains not only stocked trout, but also warmwater and coolwater fish populations which are available to anglers year-round. A previous survey conducted in 1992 and 1993 indicated quality populations of bluegill, crappie, yellow perch, and brown bullhead. Largemouth bass were also present, with some individuals achieving trophy size.

Fisheries Management personnel surveyed Keystone Lake in April 2009 using Night Flatbottom Boat Electrofishing and Pennsylvania Style Trap Nets. The purpose of the survey was to assess the lake’s warmwater and coolwater fish populations as well as to update management strategies for the lake.

Night electrofishing for 1.55 hours yielded a total of 277 largemouth bass ranging in length from 2 to 17 inches. The majority of the fish were in the 8 to 10 inch range; however 6% of the fish were larger than 12 inches. We collected more bass over 12 inches in 2009 than in surveys conducted in 1980 and 1993. A few bass were also captured in trap nets including some trophy sized fish. Similar results were seen after the 1980 and 1993 surveys in which there was an abundance of small fish and a lack of fish over 12 inches in length.

This was the first time gizzard shad were documented at Keystone Lake. Gizzard shad can sometimes serve as an important component of the diet of largemouth bass where they both occur, however they also have potential to have negative ecological consequences on other species (see below). Bluegill, golden shiners and other species can also be very important diet components.

Figure 1

Largemouth bass
Fisheries Biologist Aide Joe Cocco with a 22 inch, 7.5 lb largemouth captured in a trap net

Crappies were abundant at Keystone Lake and good numbers of quality size fish (> 9 in.) were available to anglers. A total of 173 crappie were captured in trap nets with 56% of those fish longer than 9 inches. Statewide Panfish Guidelines suggest that capture of crappie over nine inches at a rate of 0.25 per trapnet hour indicates an acceptable crappie population. The 2009 survey at Keystone Lake yielded a catch rate of crappie over 9 inches at 0.38 per hour.

Figure 2

Area 8 Fisheries Biologist Mike Depew with two nice white crappies

Good numbers of bluegill were captured during our survey; however the size structure of the bluegill population has declined since the previous survey. More fish were captured but most had not attained quality size. This may be due to the recent introduction of gizzard shad into Keystone Lake. Gizzard shad compete with bluegills for food resources which often lead to reduced growth in the bluegill population.

Figure 3

Yellow perch showed a similar trend as bluegill at Keystone Lake in 2009. Overall numbers were similar to 1993, but fewer quality size fish were captured. Competition with gizzard shad is likely reducing the growth of yellow perch.

Figure 4

Other species captured during the survey included pumpkinseed, brown bullhead, yellow bullhead, white sucker, rainbow trout, gizzard shad, green sunfish, common carp, golden shiner, bluntnose minnow, and tiger muskellunge. Stocking of tiger muskellunge was discontinued in 2004, although a few remain.

Area 8 Fisheries Manager Rick Lorson with a 38” tiger musky

Overall, Keystone Lake provides a good fishery for stocked rainbow trout and both black and white crappie. Bluegill are abundant although sizes are generally small. Largemouth bass are plentiful with the occasional fish reaching trophy size.

Table 1. Fish species captured from night electrofishing and trap netting at
Keystone Lake, Westmoreland County during April 2009.
Fish Species Number Collected Size Range (inches) Additional Comments
Largemouth bass 182 2-22 in. 6% over 12 inches
White crappie 144 6-12 in. 68% over 9 inches
Black crappie 34 3-9 in. 11% over 9 inches
Bluegill 611 2-7 in.  < 1% over 7 inches
Yellow perch 77 2-10 in. 3% over 9 inches
Pumpkinseed 20 3-6 in. 0% over 7 inches
Brown bullhead 19 12-14 in.  
Yellow bullhead 2 9-10 in.  
Tiger muskellunge 3 37-39 in.  
Rainbow trout 45 Not measured  
Common carp 2 Not measured  
Gizzard shad 474 Not measured  
Golden shiner 8 Not measured  
White sucker 26 Not measured  
Bluntnose minnow 1 Not measured  
Green sunfish 2 Not measured  
-- Prepared by Area 8 Fisheries Biologist Mike Depew

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