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Pymatuning Lake

Spring Trap Net Fish Indexing

Crawford County
Spring 2006

Fisheries Management personnel sampled Pymatuning Lake from March 27 to April 7, 2006. Trapnets were set at 34 sites for a total of 785.25 hours of trapnet effort. A total of over 8,800 fish were sampled representing 25 species of fish.

Walleye ranged in size from 8.1 to 28.1 inches with a total of 917 walleye caught. Legal length fish made up over 98% of the catch with 71% of the fish over 18 inches and 32% of the walleye over 20 inches. Male walleye made up 82% of the walleye catch with the average size male about 18 inches long. Females averaged about 22 inches in length. Ten years ago the average walleye in Pymatuning Lake was 15 inches in length. It is not uncommon for walleye stocked in a particular water to exhibit very high survival such that walleye from one or two year classes predominate in the population. Those year classes currently predominating in the population were largely derived from the 2000 and earlier year classes. Since survival of more recently stocked year classes have exhibited below average survival, the number of smaller fish, below legal size, in the population is comparatively lower.

The Pennsylvania Fish and Boat Commission annually monitors survival of spring stocked fry in fall at Pymatuning Lake. Through that monitoring the Pennsylvania Fish and Boat Commission recognized the recent series of low survival years and took unprecedented steps this year (in 2006) to stock marked advanced fry into Pymatuning Lake. During fall assessments biologists will be able to assess the contribution of advanced fry versus traditional 3 day old fry to the fall survival index. The goal associated with advanced fry stocking was to determine if a survival advantage existed. Survival of fry in production ponds at Linesville during summer harvest provides insight into survival of fry stocked into Pymatuning Lake. With very high survival of fry in production ponds, management personnel are optimistic that similar conditions prevailed in Pymatuning Lake, fall assessments will be necessary to confirm or refute this prediction. Fry survival is largely dependent upon two lake or pond characteristics, adequate food (zooplankton) and few predators. Plankton production is largely dependent upon weather conditions and spring warming, predator density include density of piscivorous fishes such as black crappie and alewife. These features are not as controllable in Pymatuning Lake as in production ponds.

Species Number Caught Size Range (inches)
Walleye 917 8.1-28.1
Muskellunge 14 26.3-45.5
Black Crappie 855 2-13.5
White Crappie 50 2-13.5
Yellow Perch 192 4-13.5
Channel Catfish 92 3-27

The muskellunge trapnet catch was much lower this year with only 14 muskellunge sampled compared to 71 in 2005. Water temperatures were just starting to reach the range when musky would start to move in the spring in association with spawning when a cold front moved through the area dumping 3 inches of snow on the ground. Water temperatures dropped and spawning size fish appear to stop moving. We feel temperature changes affected assessment catches considerably.

A total of 822 black crappie were caught ranging is size from 2 inches to over 13 inches. Most of the crappies were in the 10 to 12 inch size range. Anglers should enjoy another good year fishing for crappie.

Quality size channel catfish were also caught with fish up to 27 inches long and many over 20 inches.

Fisheries personnel measure a large walleye
Fisheries personnel measure a large walleye. Large walleye predominated in Pymatuning Lake assessment catches in 2006. After measurement and scale sampling to determine age, all fish enumerated are returned to the lake.

Typical walleye
Fisheries personnel F. Johns and C. Hobbs illustrate “typical” size walleye collected in assessment catches in 2006 on a welcome sunny morning in March

Heavy walleye
In early morning during week 2 of trap net assessment, it was apparent that numerous large heavy walleye comprised the population at Pymatuning Lake, a treat for the trophy walleye hunter

-- F. Johns, Area 1 Fisheries Technician

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