# Status and Distribution of the Chesapeake Logperch
## 4 Discussion
During surveys in wadable waters, _P. bimaculata_ was captured adjacent to larger, coarse substrates like boulders, rubble, and large woody debris. In the spring and early summer, individuals, pairs, or schools of _P. bimaculata_ were often observed and/or captured over clean sand and gravel, unassociated with large, coarse substrates. In Conowingo Pond, Susquehanna River, similar habitats were generally present when _P. bimaculata_ was collected at tributary mouths, islands, and shorelines, but observing the position of fish in relation to substrates was not possible, especially when using benthic trawls. We have also observed young-of-year fish and juveniles occupying the same locations as adults. We found _P. bimaculata_ to occupy three reservoirs in Pennsylvania, including Conowingo Pond, Octoraro Reservoir, and Muddy Run Recreation Lake. Populations of _P. bimaculata_ occurring in reservoirs mimic the natural use of lacustrine systems by _P. caprodes_ and its adaptability to impoundments [60; 84; 85; 86]. It is likely the Muddy Run Pumped Storage Impoundment is also occupied at times, given the presence of _P. bimaculata_ near its intake structures in the Susquehanna River and the populations present above it in Muddy Run Recreation Lake. The Pumped Storage Impoundment is a novel environment given the radical swings created by the operation of the facility for electric power generation. Conservation and Threats: The demonstrated tolerance of impoundments by _P. bimaculata_ suggests that reintroduction efforts above Holtwood and Safe Harbor dams have the potential to reestablish populations mimicking those of Conowingo Pond, Muddy Run Recreation Lake, and Octoraro Reservoir. Dam removals on tributaries to the Susquehanna River above Holtwood have reunited the river with additional kilometers of suitable habitats composed of sand, gravel, rubble, and boulder substrates. For example, multiple impassable dams on Chiques Creek were recently removed, including one near its mouth (Heistand Sawmill Dam) in 2015. Pequea Creek was once dammed for an early hydroelectric operation near its mouth and is now open to the Susquehanna River again. Recovery within the zone of extirpation (York Haven to Holtwood) appears to be plausible, but challenges still exist there and to extant populations in Conowingo Pond, its tributaries, and Octoraro Creek. Impingement of the logperch has been reported [71] at the Peach Bottom Atomic Power Station and still occurs [87]. Entrainment almost certainly occurs at the Muddy Run Pumped Storage Facility. If _P. bimaculata_ was to recolonize the Susquehanna River above Holtwood, impingement at cooling water intakes associated with Brunner Island Steam Electric Station would also be expected. Depauperate native fish assemblages such as that of the Susquehanna River Basin have been characterized as vulnerable to non-native invasions [88]. Introduced fish species richness has been generally related to large-scale environmental disturbances [89]. [PERSON] et al. [13] and [PERSON] [90] reported a rather large portion of the Susquehanna River's total fish diversity to be composed of introduced species, 28% and 31%, respectively, which rank among the highest within the central Appalachians and central Atlantic Coastal Plaindrainages [13]. We found approximately 46% of the species (11 of 24) collected during the 2010 survey of the lower Susquehanna River to be introduced. Competition for space and resources with introduced species of similar habitat preferences and feeding builds may be a significant interspecific threat to _P. bimaculata_. Of particular concern are the introductions of the Banded Darter (_Etheostoma zonale_) [49; 62] and Greenside Darter (_E. lebunioides_) [49] to the Susquehanna basin, presumably in the 1960s. The Susquehanna River Basin has a depauperate native darter fauna consisting of five species, one of which is rare (_P. bimaculata_), and another is exitrputed (_E.