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Exotic Fish Found in Glade Run Lake, Leads to Concerns about Lake's Fishery

Updated: Feb 4, 2023

Written by Dave Fowler, GRLC Board Member

Any healthy ecosystem is comprised of a great web of different species that interact with one another in a variety of ways. To keep this type of natural community thriving, it's important there be a balance of "actors" - from large game, fish, small minnows and plants, to insects and microscopic plants and animals. If this balance (that has developed over thousands of years) is disrupted, the entire ecosystem can be upset to the point that it's no longer able to sustain itself.

Glade Run Lake is such an ecosystem.

With the restoration of the lake completed in 2017, the reestablishment of a healthy ecologic community was begun with the goal of bringing back a prime sportfish fishery. The Glade Run Lake Conservancy is currently working closely with the Pennsylvania Fish and Boat Commission (PFBC) and other organizations to make Glade Run Lake one of the best fishing spots in the region (a goal that has already seen significant progress!). This endeavor was recently confirmed by some of the best professional fishermen in the country when they came to the lake for a visit, saying “In a few more years, this lake will provide some of the best fishing in the state.” (See: Fishing University on the Outdoor Channel).

However, the goal of advancing the lake's fishery could be threatened by the introduction of unwanted exotic or nonnative species. These species have the potential to upset the delicate ecological balance of the lake through predation, harming water quality, and the introduction of disease.

Recently, a fish identified as a Pacu, native to South America, was observed on the bank at Glade Run Lake. (See image included in this blog post.) Because this species is native to warmer climates, it cannot survive in colder waters (such as in Glade Run Lake). However, its presence at Glade Run Lake is cause for concern. This finding provides a real-world example of the introduction of an exotic species that could be very destructive to our lake.

Other fish species more common to Pennsylvania such as gizzard shad, alewives, common carp, or northern pike can also have serious detrimental effects on Glade Run Lake. These species can cause significant alterations in a food web as well as water quality.

Fish not from Glade Run Lake should never be placed in the lake. This important advice is valuable to remember in order to have a great fishery and a healthy and functioning aquatic ecosystem. Please leave fish stocking to the professionals. It is a delicate balance that is carefully monitored to make sure there are lots of big bass in the future.

In addition to outcompeting native fish for resources and the potential to introduce disease, fish released into the lake can access other areas of the Glade Run Lake watershed and beyond. In understanding this fact, it becomes clear that it's not only the lake that can be endangered!

The following video titled "Don't Dump That Fish" discusses the issues related to introducing exotic fish species into a waterbody.

There are many ways to dispose of bait fish and unwanted tropical fish. Bait fish should always be disposed of well away from the lake/waterbody where an angler is fishing. A single bait dealer harvests minnow species from a variety of ponds, wetlands, and streams, and chances are good that some of those species are not native to the lakes or rivers anglers commonly fish in.

Individuals should consider returning tropical fish to a local pet shop for resale or trade, or giving them to another hobbyist (including an aquarium) in a professional office, museum, school, nursing home, or to a public aquarium or zoological park. Additionally, organizations such as Pennsylvania Sea Grant will sometimes host periodic pet surrender events.

If these options are not available, a veterinarian or fishery biologist can euthanize unwanted fish species with anesthetic. Individuals can also do this at home by placing an unwanted fish in a container of water and putting it into the freezer. Because cold temperature is a natural anesthetic to tropical fishes, this is considered a very humane method of euthanasia. A pet shop may also be able to assist if euthanasia is the option chosen.

The following is a statement from the Pennsylvania Fish and Boat Commission (PFBC) regarding the importance of not dumping any fish (or other animal or plant species) into Glade Run Lake:

"The plan to restore the warm water fish community at Glade Run Lake was a carefully considered plan utilizing native species well suited for a small reservoir. Unauthorized fish stockings often do more harm than good and could create dramatic negative ecological consequences on the lake's food web and/or water quality. All of this could ultimately degrade the quantity of sportfish and the quality of the fishing. The PFBC will continue to monitor the development of the fish community and stock the fish necessary to create and maintain good fishing in Glade Run Lake. Please refrain from stocking any fish in Glade Run Lake without first consulting the PFBC."

Help preserve and improve Glade Run Lake by following the recommendations given by local and state organizations (such as the PFBC, PA Sea Grant, and Habitattitude) for maintaining a healthy ecosystem in our beautiful lake. The Glade Run Lake Conservancy thanks you for your understanding of and cooperation with this issue. (When Glade Run Lake is the best big bass lake in the region, you and future generations will be glad you did!)

Thank you!

Dave Fowler (pictured above) is an active board member with the Glade Run Lake Conservancy and was one of the original founders of the organization when it began in 2011. Dave's involvement with Boy Scout and Eagle Scout projects as well as time spent conducting water quality testing are just some of the projects he takes part in to show his dedication to this special place in our community. Dave enjoys spending his spare time at the lake too where he can be seen paddling with his wife (and their dog) on their kayaks, or photographing the lake's plethora of birds and other wildlife.

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