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SUSQUEHANNA RIVER BASIN REPORT Submitted by John Seitz Basin Director, PA-AWRA, Susquehanna Basin Invasive Species of the Susquehanna Basin Invasive species are plants and animals that have been introduced to an ecosystem and cause economic, environmental, and health problems. The problem of invasive species is not unique to the Susquehanna Basin, but it is important to understand that a plant or animal may be native to one Pennsylvania watershed, but be invasive in the Susquehanna Basin. One of the problems with understanding invasive species is determining the impacts resulting from their introduction. Much time and research is often required to understand the consequences of the introduced invasive species. In order to properly manage an invasive species, important environmental, economic, and social questions need to be answered. According to biologist Geoffrey Smith of the Pennsylvania Fish & Boat Commission (PFBC), many invasive species are causing multiple issues in the Susquehanna Basin, but several specific species hold a higher priority concerning a management strategy at the present time. A few invasive species of concern in the Susquehanna Basin are described below. Rusty Crayfish predation, the rusty crayfish will displace entire populations of native crayfish. According to Smith, the rusty crayfish has essentially extirpated the native crayfish from the main stem Susquehanna and many of its warm water tributaries. Very difficult to control once introduced, the most efficient management technique to control rusty crayfish populations is to prevent their introduction. Almost all invasive crayfish introductions result from actions of humans, such as emptying bait containers or pet aquariums. Educating people on identification of crayfish species, methods and ramifications of spreading non-native crayfish, and techniques to be used to prevent/reduce the spread of rusty crayfish are critical to the management plan to control this invasive species. Flathead Catfish Flathead catfish is a species that is native to some Pennsylvania river systems, but invasive in others, including the Susquehanna Basin. Named after its broad flat head, flatheads have a distinctive lower jaw that projects out past its upper jaw. It grows larger than the Susquehanna’s native catfish. Differing from most catfish species, the flathead is not a scavenger and preys primarily on live fish. According to the Susquehanna River Basin Commission (SRBC), Flathead catfish were first found to be reproducing in the lower and central Susquehanna River in Photo: Casey Swecker - Marshall University 2005. Rusty crayfish are an aggressive species that grow very rapidly, thereby greatly reducing the amount of time this species is most susceptible to fish predation. Occurring at very high densities compared to native crayfish, the rusty is an efficient omnivore. Rusty crayfish eat aquatic vegetation, benthic macroinvertebrates, detritus, and fish eggs, potentially resulting in lower fish productivity. Through direct competition and 10 | | InInthe 8 theFlow Flow- -Winter Spring/Summer 2012 - Spring 2012 2013 PFBC’s Smith notes that flatheads appear to grow much faster in the Susquehanna River Basin when compared to growth rates in those basins where the flathead is native. In the Ohio River, a fish the size it would take 20 years to attain may reach that same size in the Susquehanna within10 years. Management of this species must take into account any detrimental impacts to the natural balance of the Susquehanna, but must also weigh an important social aspect, increased angling opportunities the flathead presents. Although it appears that the flathead catfish is “here to stay” in the Susquehanna Basin, any management plan for this aquatic predator must consider its detrimental impacts to the ecosystem, as well as, the positive recreational impacts. It is unlawful to possess, introduce, transport or sell Asian carp in Pennsylvania. According to the PFBC, the only way these fish would occur is if transported and released. Asian carp are a threat due to their large size, reproductive success, habitat damage and large, year-round food consumption. They can constitute up to 90% of the biomass in infested waters, wiping out native fish and mussel populations. Also, certain species of Asian carp, when startled, jump out of the water causing safety issues for boaters and skiers. Hemlock Wooly Adelgid The hemlock wooly adelgid is an invasive insect that lacks natural enemies in the Basin. Photo: U.S. Forest Service An example of a terrestrial invasive having detrimental impacts on aquatic resources, this insect uses the eastern hemlock tree as its host, sucking sap from its branches and often causing death of the tree within a few years. Smith explains that the loss of the eastern hemlock could be concerning because most of Pennsylvania’s brook trout streams are located in heavily forested drainages, where hemlock trees protect streambanks and shade the water. Brook trout need clean cold water to survive and such conditions depend heavily on the adjacent hemlocks. As the hemlock wooly adelgid threatens the eastern hemlock, so too it threatens the brook trout. Management of Invasive Species Andar Rehm, 2010 (caught at York Haven) Once introduced, invasive species can be next to impossible to eliminate. Many times, the best management technique is to prevent introduction and/or spreading of unwanted species. Education and awareness may well be the most effective means of keeping invasive species in check. Asian Carp Selected Resources This aquatic invasive species is not yet found in Pennsylvania, but due to the devastating impact it has had in the Mississippi River and the threat it now poses to the Great Lakes, heightened efforts to prevent introduction to Pennsylvania waters are necessary. PFBC: Clean Your Gear - http://fishandboat.com/ cleanyourgear.htm. SRBC: Invasive Species TIP Sheet; How You Can Help - http://www.srbc.net/anniversary/assets/pdf/ Invasive%20Species%20Tip%20Sheet.pdf. In the Flow - Winter 2012 - Spring 2013 | 9