BIOLOGIST REPORT

Lake Magnolia

2002 Channel Catfish Survey


In an attempt to provide enhanced recreational fishing opportunities at Lake Magnolia, a 26 acre Bucks County Parks lake, a total of 13,550 fingerling channel catfish have been stocked by the Pennsylvania Fish and Boat Commission since 1983. Trap netting was conducted at Lake Magnolia from June 12 through June 14, 2000 for the purpose of evaluating these stockings. Results from the 2000 survey were inconclusive requiring that the lake be resurveyed in 2002.

Lake Magnolia
View of Lake Magnolia from South Shore Looking West

From June 10 through June 12, 2002, six Pennsylvania style trap nets were fished to reevaluate the fingerling channel catfish stocking program at Lake Magnolia. Two of the net sets had extremely poor catches of fish as a result of being set below the thermocline (The thermocline divides warmer oxygen rich water from cooler oxygen poor water). The pot depths of these two sets were 8 feet and 10 feet. These nets were excluded from the evaluation.

Not including the capture of 5 fingerling channel catfish resulting from a stocking which took place six days prior to the survey, a total of 4 channel catfish ranging from 16 inches – 22 inches total length (TL) were captured for a catch per unit of effort (CPUE) of 0.04 fish/hr. The average CPUE of channel catfish collected at other impoundments surveyed in southeast Pennsylvania was 0.20 fish/hr. The CPUE of channel catfish collected from Lake Magnolia was significantly less than the southeast Pennsylvania average.

It was hypothesized that either heavy angling pressure or poor fingerling channel catfish survival accounted for the poor returns in 2000. Following the 2002 survey it was apparent that predation by both a dense brown bullhead population and a dense mixed black and white crappie population had the potential to limit the success of the channel catfish stocking program. Additionally, likely escapement of channel catfish out of Lake Magnolia into nearby Silver Lake via a connecting channel that permits free passage of fish between the lakes may have contributed to the poor catch of channel catfish during the trap netting survey.

Crappie collected from trap net at Magnolia Lake
Crappie Collected from Trap Net at Magnolia Lake

During the 2002 survey brown bullheads were captured at a rate of 2.10 fish/hr. This was considerably greater than the southeast Pennsylvania average of 0.30 fish/hr. Brown bullheads ranged in lengths from 3 inches to 14 inches TL with the majority being 8 inches to 10 inches TL. The CPUE of the mixed black and white crappie population was 7.87 fish/hr. This was greater than twice the southeast Pennsylvania average crappie CPUE of 3.35 fish/hr. Crappie at Lake Magnolia ranged from 3 inches to 12 inches TL with the majority being 5 inches to 8 inches TL.

Typical size brown bullhead collected from trap net
Typical Size Brown Bullhead Collected from Trap Net

The stocking of 13,550 fingerling channel catfish in Lake Magnolia since 1983 has failed to produce a quality recreational angling opportunity for channel catfish. As a result, future plantings of fingerling channel catfish into Lake Magnolia should be discontinued. Stocking of channel catfish into this urban lake should be reconsidered if a reliable source of larger channel catfish more capable of avoiding predation becomes available. If possible, Silver Lake should be examined for the presence of the stocked channel catfish.

 Large snapping turtle collected in trap net
 Large Snapping Turtle Collected in Trap Net

-- Area 6


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