Regular issues
Special Issues



Urban Naturalist
    URNA Home
    Board of Editors
    Staff
    Editorial Workflow
    Publication Charges
    Subscriptions

Other Eagle Hill Science Journals
    Northeastern Naturalist
    Southeastern Naturalist
    Caribbean Naturalist
    Neotropical Naturalist
    Prairie Naturalist
    Eastern Paleontologist
    Journal of the North Atlantic
    eBio

Eagle Hill Institute Home

Occurrence of Shortnose Sturgeon in the Tidal Schuylkill River, an Urbanized and Industrialized Tributary of the Delaware River

Harold M. Brundage III1

1Environmental Research and Consulting, Inc., Lewes, DE, USA 19958. Corresponding author.

Urban Naturalist, No. 47 (2021)

Abstract
Monitoring for acoustically-tagged sturgeon was conducted in the tidal Schuylkill River (Philadelphia, PA, USA), a highly urbanized and industrialized tributary of the Delaware River, during July 2018 through July 2019. Three adult Shortnose sturgeon were detected, initially during the summer and/or fall of 2018. The same fish were detected again in the spring and/or summer of 2019. Periods of continuous occupancy in the Schuylkill River ranged from 12–67 days and averaged 38.3 days. The Shortnose Sturgeon were absent from the Schuylkill River during the winter months but utilized known overwintering areas in the tidal Delaware River. This study suggests that a small percentage (~3% based on the proportion of acoustically-tagged Shortnose Sturgeon detected vs. at large) of adult Delaware River Shortnose Sturgeon seasonally utilize the tidal Schuylkill River, probably as a foraging area. The study also suggests that water quality in the Schuylkill River, particularly dissolved oxygen concentration, is generally suitable for adult Shortnose Sturgeon and provides further evidence that tributaries and smaller river systems may serve a more important role in the life history of Shortnose Sturgeon than previously thought.

pdf iconDownload Full-text pdf

 

 

Site by Bennett Web & Design Co.
No. 47 Urban Naturalist 2021 Occurrence of Shortnose Sturgeon in the Tidal Schuylkill River, an Urbanized and Industrialized Tributary of the Delaware River Harold M. Brundage III Urban Naturalist The Urban Naturalist (ISSN # 2328-8965) is published by the Eagle Hill Institute, PO Box 9, 59 Eagle Hill Road, Steuben, ME 04680- 0009. Phone 207-546-2821 Ext. 4, FAX 207-546-3042. E-mail: office@eaglehill.us. Webpage: http://www.eaglehill.us/urna. Copyright © 2021, all rights reserved. Published on an article by article basis. Special issue proposals are welcome. The Urban Naturalist is an open access journal. Authors: Submission guidelines are available at http://www.eaglehill.us/urna. Co-published journals: The Northeastern Naturalist, Southeastern Naturalist, Caribbean Naturalist, and Eastern Paleontologist, each with a separate Board of Editors. The Eagle Hill Institute is a tax exempt 501(c)(3) nonprofit corporation of the State of Maine (Federal ID # 010379899). Board of Editors Myla Aronson, Rutgers University, New Brunswick, NJ, USA Joscha Beninde, University of California at Los Angeles, CA, USA. Sabina Caula, Universidad de Carabobo, Naguanagua, Venezuela Sylvio Codella, Kean University, Union New Jersey, USA Julie Craves, University of Michigan-Dearborn, Dearborn, MI, USA Ana Faggi, Universidad de Flores/CONICET, Buenos Aires, Argentina Leonie Fischer, Technical University of Berlin, Berlin, Germany Chad Johnson, Arizona State University, Glendale, AZ, USA Kirsten Jung, University of Ulm, Ulm, Germany Erik Kiviat, Hudsonia, Bard College, Annandale-on- Hudson, NY, USA Sonja Knapp, Helmholtz Centre for Environmental Research–UFZ, Halle (Saale), Germany David Krauss, City University of New York, New York, NY, USA Mark Laska, Great Ecology, consulting, La Jolla, CA, USA Joerg-Henner Lotze, Eagle Hill Institute, Steuben, ME. Publisher Kristi MacDonald, Hudsonia, Bard College, Annandale-on- Hudson, NY, USA Ian MacGregor-Fors, University of Helsinki, Finland. Editor Tibor Magura, University of Debrecen, Debrecen, Hungary Brooke Maslo, Rutgers University, New Brunswick, NJ, USA Mark McDonnell, Royal Botanic Gardens Victoria and University of Melbourne, Melbourne, Australia Mike McKinney, University of Tennessee, Knoxville, TN, USA Desirée Narango, University of Massachusetts, Amherst, MA, USA Mitchell Pavao-Zuckerman, University of Arizona, Tucson, Arizona, USA Joseph Rachlin, Lehman College, City University of New York, New York, NY, USA Travis Ryan, Center for Urban Ecology, Butler University, Indianapolis, IN, USA Michael Strohbach, Technische Universität Braunschweig, Institute of Geoecology, Braunschweig, Germany Katalin Szlavecz, Johns Hopkins University, Baltimore, MD, USA Alan Yeakley, Portland State University, Portland, OR, USA Iriana Zuria, Universidad Autónoma del Estado de Hidalgo, Hidalgo, Mexico ♦ The Urban Naturalist is a peer-reviewed and edited interdisciplinary natural history journal with a global focus on urban areas (ISSN 2328- 8965 [online]). ♦ The journal features research articles, notes, and research summaries on terrestrial, freshwater, and marine organisms and their habitats. ♦ It offers article-by-article online publication for prompt distribution to a global audience. ♦ It offers authors the option of publishing large files such as data tables, and audio and video clips as online supplemental files. ♦ Special issues - The Urban Naturalist welcomes proposals for special issues that are based on conference proceedings or on a series of invitational articles. Special issue editors can rely on the publisher’s years of experiences in efficiently handling most details relating to the publication of special issues. ♦ Indexing - The Urban Naturalist is a young journal whose indexing at this time is by way of author entries in Google Scholar and Researchgate. Its indexing coverage is expected to become comparable to that of the Institute's first 3 journals (Northeastern Naturalist, Southeastern Naturalist, and Journal of the North Atlantic). These 3 journals are included in full-text in BioOne.org and JSTOR.org and are indexed in Web of Science (clarivate.com) and EBSCO.com. ♦ The journal's staff is pleased to discuss ideas for manuscripts and to assist during all stages of manuscript preparation. The journal has a page charge to help defray a portion of the costs of publishing manuscripts. Instructions for Authors are available online on the journal’s website (http://www.eaglehill.us/urna). ♦ It is co-published with the Northeastern Naturalist, Southeastern Naturalist, Caribbean Naturalist, Eastern Paleontologist, Eastern Biologist, and Journal of the North Atlantic. ♦ It is available online in full-text version on the journal's website (http://www.eaglehill.us/urna). Arrangements for inclusion in other databases are being pursued. Cover Phograph: Adult Shortnose Sturgeon captured in the upper tidal Delaware River. Photograph © Harold M. Brundage III. Urban Naturalist H.M. Brundage III 2021 No. 47 1 2021 Urban Naturalist 47:1–11 Occurrence of Shortnose Sturgeon in the Tidal Schuylkill River, an Urbanized and Industrialized Tributary of the Delaware River Harold M. Brundage III1 Abstract - Monitoring for acoustically-tagged sturgeon was conducted in the tidal Schuylkill River (Philadelphia, PA, USA), a highly urbanized and industrialized tributary of the Delaware River, during July 2018 through July 2019. Three adult Shortnose sturgeon were detected, initially during the summer and/or fall of 2018. The same fish were detected again in the spring and/or summer of 2019. Periods of continuous occupancy in the Schuylkill River ranged from 12–67 days and averaged 38.3 days. The Shortnose Sturgeon were absent from the Schuylkill River during the winter months but utilized known overwintering areas in the tidal Delaware River. This study suggests that a small percentage (~3% based on the proportion of acoustically-tagged Shortnose Sturgeon detected vs. at large) of adult Delaware River Shortnose Sturgeon seasonally utilize the tidal Schuylkill River, probably as a foraging area. The study also suggests that water quality in the Schuylkill River, particularly dissolved oxygen concentration, is generally suitable for adult Shortnose Sturgeon and provides further evidence that tributaries and smaller river systems may serve a more important role in the life history of Shortnose Sturgeon than previously thought. Introduction Acipenser brevirostrum LeSueur (Shortnose Sturgeon) is a relatively small (<1.2 m total length (TL)) sturgeon that inhabits large Atlantic coastal rivers and estuaries from the St. John River, New Brunswick, Canada, to the St. Johns River, FL, USA (Vladykov and Greeley 1963). The Shortnose Sturgeon was placed on the Endangered Species List in 1967 and is currently listed as endangered under the federal Endangered Species Act (ESA) of 1973, as amended. The International Union for the Conservation of Nature (IUCN) Red List of Threatened Species lists Shortnose Sturgeon as Vulnerable (VU) (A2ce; B1ab(iii)) (IUCN 2020). Shortnose Sturgeon occur throughout the Delaware River estuary (Brundage and Meadows 1982). Adults are abundant in the upper tidal Delaware River from Trenton, NJ to Philadelphia, PA year-round (ERC 2006a, Hastings et al. 1987), and relatively common in the lower tidal river from approximately Chester, PA to Wilmington, DE (ERC 2006a, 2010, 2020). The Delaware River estuary supports the third largest population of Shortnose Sturgeon range wide; the Hudson River (NY) and the St. John River having larger estimated populations (Kynard et al. 2016). Environmental Research and Consulting, Inc. (ERC) (2006b) estimated the population of adult Shortnose Sturgeon in the Delaware River to be 12,047 (95% CI 10,757–13,589) using the Schnabel population estimator with markrecapture data collected during 1999–2003. This estimate, which is the most recent available, was very similar to an earlier Schnabel estimate of the Delaware River adult Shortnose Sturgeon population of 12,796 (95% CI 10,228–16,367) based on mark-recapture data from 1981–1984 (Hastings et al. 1987). The similarity of the estimates suggests that the population of adult Shortnose Sturgeon in the Delaware River was stable during the approximately 20 year period between the estimates. 1Environmental Research and Consulting, Inc., Lewes, DE, USA 19958. Corresponding author: hbrund1124@aol.com. Associate Editor: Sonja Knapp, Helmholtz Centre for Environmental Research–UFZ. Urban Naturalist H.M. Brundage III 2021 No. 47 2 Delaware River Shortnose Sturgeon overwinter in dense aggregations in the upper tidal river between Roebling and Bordentown, NJ, and also in the lower tidal river in the vicinity of Marcus Hook and Chester (ERC 2006a, Hastings et al. 1987). Spawning occurs primarily in the lower non-tidal Delaware River from Trenton to Lambertville, NJ from late March or early April into early May (Brundage 1986; ERC 2008, 2015, 2018). After spawning, adult Shortnose Sturgeon move back to the tidal river, where they spend the summer and fall foraging, with fish occasionally moving into Delaware Bay (O’Herron et al. 1993, ERC 2006a). Delaware River Shortnose Sturgeon generally remain in the estuary throughout their lives, although there are a few records of their occurrence in the ocean near the mouth of Delaware Bay (Brundage and Meadows 1982). Juvenile Shortnose Sturgeon in the Delaware River co-occur with adults but, being sensitive to salinity (Jarvis et al. 2001), generally remain upriver of the freshwater/saltwater interface (Brundage and O’Herron 2009, O’Herron et al. 1993). Juvenile Shortnose Sturgeon appear to overwinter in a dispersed fashion rather than in the aggregations typical of adults (Brundage and O’Herron 2009). Effects of Urbanization on Shortnose Sturgeon Urbanization and associated industrialization have impacted Shortnose Sturgeon in a number of ways. Construction of dams has blocked upstream spawning migrations and denied Shortnose Sturgeon access to historic spawning sites in a number of rivers, including the Connecticut (CT) (Kynard 1997), Hudson (NY) (Bain 1997), and Cooper (SC) rivers (Cooke and Leach 2003), resulting in spawning and early life stage rearing in suboptimal environments (Kynard 1997, Kynard et al. 2016). The Delaware River, however, has remained undammed, so Shortnose Sturgeon have unimpeded access to spawning areas in the non-tidal river. Deterioration of water quality associated with urbanization and industrialization, especially reduction in dissolved oxygen concentration, has had a significant impact on Shortnose Sturgeon in some rivers. Laboratory studies have shown that juvenile Shortnose Sturgeon and other sturgeons are very sensitive to hypoxia (Campbell and Goodman 2004, Secor and Gunderson 1998, Secor and Niklitschek 2001), with younger juveniles being more susceptible than older juveniles (Jenkins et al. 1993). Although laboratory studies are lacking, adult Shortnose Sturgeon are also presumed to be sensitive to low dissolved oxygen, but perhaps less so than juveniles, since resting oxygen consumption has been shown to decrease with body mass for other sturgeon species (Peake 2005). Low dissolved oxygen concentrations caused by pulp mill effluent are thought to have made portions of the Satilla and St. Marys rivers in Georgia, and the Penobscot River in Maine unusable by Shortnose Sturgeon (Kynard et al. 2016). Low dissolved oxygen is also believed to have historically impacted Shortnose Sturgeon in the upper tidal Hudson River, and the large (400%) increase in the estimated Shortnose Sturgeon population in the Hudson between the 1970s and the late 1990s has been attributed, in part, to the return of normoxic conditions (Bain et al. 2007, Secor and Niklitschek 2001). Low dissolved oxygen has affected the distribution and movements of Shortnose Sturgeon in the urbanized/industrialized central portion of the tidal Delaware River, both historically and more recently. Brundage and Meadows (1982), reviewing incidental capture records during 1954 through 1979, concluded that the Delaware River between Philadelphia and Wilmington would be unavailable to Shortnose Sturgeon during summer as a result of near zero dissolved oxygen concentrations. Although water quality in the Delaware River has improved significantly since the 1980s, dissolved oxygen concentrations near Philadelphia may still drop to stressful levels (~3–5 mg/l) during hot, dry summers (Moberg and DeLucia Urban Naturalist H.M. Brundage III 2021 No. 47 3 2016). Acoustic tracking studies conducted during 2003–2004 (ERC 2006a) and 2009 (ERC 2010) indicated that adult Shortnose Sturgeon utilized the Philadelphia reach of the river as a travel corridor when moving between overwintering, spawning, and foraging areas but did not remain in that part of the river for long periods of time. Brundage and O’Herron (2009) concluded that acoustically-tagged juvenile Shortnose Sturgeon were unlikely to use the Philadelphia area in summer because of low dissolved oxygen concentrations. Chemical contaminants released from urban areas and industrial sites may also impact Shortnose Sturgeon. Shortnose Sturgeon early life stages appear to be particularly vulnerable to contaminants, with effects ranging from sublethal deformities to mortality (Chambers et al. 2012, Kocan et al. 1996, McConnell and Chambers 2018). Shortnose Sturgeon are known to bioaccumulate various inorganic and organic chemicals, but studies linking contaminant body burdens to effects in sturgeon are lacking. ERC (2002) reported that adult Shortnose Sturgeon collected from the Delaware River had concentrations of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), polychlorinated biphenyls (PCBs), dichlorodiphenyldichloroethylene (DDE), aluminum, cadmium, and copper in gonad and liver tissue above adverse effect concentrations reported for other fish species. PCDDs, PCDFs, PCBs, DDE, and cadmium have been ide ntified as endocrine disrupting compounds (EDCs), and there is evidence that the adverse effects of these chemicals may be exacerbated when they occur in combination (Monosson 1997). Matsche et al. (2012) identified a relatively high incidence of intersex (11.6%), as well as altered hormone levels, in adult Shortnose Sturgeon collected in the upper tidal Delaware River, which could have been caused by exposure to EDCs, perhaps in combination with hypoxia, but cautioned that additional study would be needed to determine if reproduction was being affected. While Shortnose Sturgeon have been relatively well studied in the mainstem Delaware River, information on their use of tributaries is lacking. In this paper, I discuss the occurrence of Shortnose Sturgeon in the Schuylkill River, a highly urbanized and industrialized tributary of the Delaware River. Field-Site Description The Schuylkill River flows approximately 198 km from its headwaters in Schuylkill County, PA to its confluence with the tidal Delaware River at Philadelphia (the confluence of the Schuylkill River with the Delaware River is located at Delaware River kilometer (rkm) 148.8 based on DRBC (1969)). Tidal influence in the Schuylkill River is limited by Fairmount Dam, located 13.6 km from the confluence. The tidal Schuylkill River is fresh water year round. The tidal segment of the Schuylkill River is located entirely within the City of Philadelphia, and adjacent land areas are heavily industrialized and densely populated. Much of the shoreline of the tidal Schuylkill River has been bulkheaded, and there is little shallow water habitat. The lower 10 km of the Schuylkill River has been dredged for navigation. The river bottom consists of course sand and gravel overlain by mud and contains a large percentage of anthracite coal from historical coal mining upriver (Ettinger 1982). Water quality in the tidal Schuylkill River has historically been degraded by sewage, industrial effluents, and urban runoff (Kaufman et al. 2011). Methods Capture, Handling, and Acoustic Tagging of Sturgeon Shortnose Sturgeon and Acipenser oxyrinchus oxyrinchus Mitchell (Atlantic Sturgeon) were captured for acoustic tagging by bottom-set gill net (5.1–15.2 cm stretched mesh) Urban Naturalist H.M. Brundage III 2021 No. 47 4 or semi-balloon trawls (4.9 or 16.2 m mouth widths) in the upper tidal (~ rkm 210) or lower tidal Delaware River (between approximately rkm 123–140) during November 2011 through February 2019 in studies funded by the National Marine Fisheries Service (NMFS) and the US Army Corps of Engineers (USACE). Sturgeons were carefully removed from the nets and placed in an out-board live car or an on-board tank containing river water at ambient temperature and dissolved oxygen levels. Sturgeon were identified to species, measured for fork length (FL) and total length (TL), weighed, and tagged with a numbered T-bar tag (Floy Tag and Manufacturing, Inc., Seattle, WA), and/or a passive integrated transponder (PIT) (Biomark, Inc., Boise, ID). Selected sturgeon were internally tagged with Vemco (now Innovasea Systems, Inc., Shad Bay, Nova Scotia, Canada) 69 kHz coded acoustic transmitters (model V8, V9, V13, or V16) matched to the weight of the fish. Sturgeon for acoustic tag implantation were anesthetized using tricaine methanesulfonate (MS-222) at a dose of 50–100 mg/l and then held upside down in a cradle while the gills were perfused with aerated flowing water. The transmitter was inserted into the body through a longitudinal incision in the abdomen. The incision was closed with interrupted sutures of 3-0 polydioxanone (PDS), and treated with povidone iodine (10% solution) and petrolatum to prevent infection. Post surgery, fish were held in an aerated holding tank and released upon recovery from anesthesia. Shortnose and Atlantic sturgeons are tolerant of handling and tag implantation surgery, and, based on subsequent acoustic tag detections, it is unlikely that any mortality resulted from the procedures. All sampling and handling of sturgeon followed established protocols (Kahn and Mohead 2010) and was performed in accordance with NMFS Permits to Take Endangered Species for Scientific Purposes Nos. 14604, 16438, or 19331 or requirements of NMFS Biological Opinions issued for the USACE Delaware River Main Channel D eepening Project. Monitoring for Acoustically-tagged Sturgeon in the Tidal Schuylkill River Monitoring for acoustically-tagged sturgeon in the tidal Schuylkill River was conducted during July 17, 2018 through July 17, 2019 using Vemco VR2W omnidirectional receivers deployed at two locations, 1.2 and 5.9 km upriver of the confluence with the Delaware River (Fig. 1). Based on calculated tag life, 89 Shortnose Sturgeon (6 juveniles and 83 adults) and 81 juvenile Atlantic Sturgeon were at large in the Delaware River with active acoustic tags when the Schuylkill River receivers were deployed in July 2018, and an additional 23 Shortnose Sturgeon (6 juveniles and 17 adults) and 107 juvenile Atlantic Sturgeon were tagged in January–February 2019 and, thus, available for detection during approximately the second half of the receiver deployment period. Results Three adult Shortnose Sturgeon (tag codes 16490, 20767, and 55377), but no juvenile Shortnose Sturgeon or juvenile Atlantic Sturgeon, were detected by the Schuylkill River receivers (Table 1). The Shortnose Sturgeon occurred during two periods, initially in the summer and/or fall of 2018 and again in the spring and/or summer of 2019 (Fig. 2). Collectively, the Shortnose Sturgeon were present in the Schuylkill River during mid-April through mid-November but were absent during the winter months. The Shortnose Sturgeon moved back and forth between receivers and were sometimes detected by both receivers on the same day. Periods of continuous occupancy in the Schuylkill River ranged from 12–67 days (Table 1) and averaged 38.3 days. The mean lengths and weight of the Shortnose Sturgeon detected in the Schuylkill River (865 mm TL, 766 mm Urban Naturalist H.M. Brundage III 2021 No. 47 5 FL, and 4.36 kg) (Table 1) were considerably greater than the mean lengths and weight of acoustically-tagged adults at large in the Delaware River (781 mm TL, 675 mm FL, and 2.93 kg). The three Shortnose Sturgeon were detected at receivers throughout the tidal Delaware River during the periods they were not in the Schuylkill River. Shortnose Sturgeon tag code 16490 overwintered in the lower tidal Delaware River between Wilmington (rkm 112) and Marcus Hook (rkm 129), and tag codes 20767 and 55377 overwintered in the upper tidal Delaware River between Roebling (rkm 199) and Bordentown (rkm 207). Tag code 55377 Figure 1. Locations of acoustic receivers on the tidal Schuylkill River, City of Philadlephia, PA. Table 1. Detections of acoustically-tagged Shortnose Sturgeon in the tidal Schuylkill River during July 17, 2018 through July 17, 2019. Measurements at Tagging Acoustic Tag Code Date Tagged Total Length (mm) Fork Length (mm) Weight (kg) Periods of Detection No. Days Detected No. Detections 16490 11/16/16 928 812 4.62 9/30-10/26/18 14 283 5/3-6/14/19 36 1556 Total 50 1839 20767 12/27/15 863 777 5.04 7/23-11/10/18 60 2780 4/12-7/17/19 41 5802 Total 101 8582 55377 11/15/11 803 708 3.42 7/20-28/18 12 61 4/30-7/17/19 67 668 Mean 865 766 4.36 Total 79 729 Urban Naturalist H.M. Brundage III 2021 No. 47 6 was detected on the spawning grounds in the non-tidal Delaware River near Yardley, PA (rkm 221) during March 26–April 26, 2019, just before it moved back to the Schuylkill River, swimming over 73 km in five days. Discussion There is only one previously published record of a sturgeon in the Schuylkill River. This record, which appeared in the Philadelphia Inquirer (Bauers 2014), was of an adult Shortnose Sturgeon caught by a fisherman near the base of Fairmount Dam in summer 2014. Results of the present study suggest that a small percentage (~3% based on the proportion of acoustically-tagged Shortnose Sturgeon detected vs. at large) of adult Delaware River Shortnose Sturgeon may seasonally utilize the Schuylkill River. The return of the same three fish detected in summer/fall 2018 to the Schuylkill River in spring/summer 2019 suggests a regularity to their occurrence, at least for those individuals. The results of this study, combined with the incidental capture at Fairmount Dam, suggest that the entire tidal Schuylkill River may be utilized by Shortnose Sturgeon. Although there appears to be ample invertebrate food resources in the Delaware River (Kreeger et al. 2010), it is likely that Shortnose Sturgeon use the tidal Schuylkill River as Figure 2. Occurrence of Shortnose Sturgeon tag codes 16490 (top), 20767 (middle), and 55377 (bottom) in the tidal Schuylkill River during July 17, 2018 through July 17, 2019. Urban Naturalist H.M. Brundage III 2021 No. 47 7 foraging habitat considering the times of year and long durations they spent there. Shortnose Sturgeon are benthic feeders with a broad diet, feeding opportunistically on insect larvae, crustaceans, mollusks, and polychaetes (Dadswell et al. 1984, Kynard et al. 2016). Ettinger (1982) reported 22 genera of benthic invertebrates in the tidal Schuylkill River, many of which are known prey items of Shortnose Sturgeon. The occurrence of the three Shortnose Sturgeon in the Schuylkill River may be related to an innate tendency of some individuals to roam. Acoustically-tagged adult Shortnose Sturgeon in the Delaware River typically evidence one of two generalized movement patterns, either making long excursions throughout the tidal river or remaining locally in the upper tidal river (ERC 2006a, 2010). Such dichotomy in movement behavior has been documented in other fish species (Secor 2015), and fish making more wide-ranging movements can be referred to as “roamers” or “explorers”. Secor (2015) proffers that the tendency to roam is a personality trait that is part of an individual fish’s “behavioral syndrome”, and Sih and Bell (2008) suggest that this trait may be heritable. Roamers have a tendency to explore novel situations regardless of risk (Secor 2015). Exploratory behavior allows fish to discover and utilize new areas and, thereby, extend their range if environmental conditions allow. The occurrence of the three Shortnose Sturgeon in the tidal Schuylkill River over multiple seasons indicates that environmental conditions in the system were suitable for those individuals. The Schuylkill River has a long history of pollution by municipal and industrial discharges, and urban runoff, and in the early 1900’s, it was described as “grossly polluted” and “almost exhausted of dissolved oxygen” (Stevenson 1914). Water quality in the Schuylkill River has improved through implementation of pollution control programs pursuant to the 1961 Delaware River Basin Compact, the 1972 Clean Water Act and subsequent amendments, and other initiatives. Based on analysis of 1980–2005 data, Kaufman et al. (2011) reported significant improvements in dissolved oxygen, total suspended sediment (TSS), and phosphorus concentrations in the Schuylkill River, although nitrogen concentrations remained high, probably because of the ongoing input of organic matter to the river. There are no dissolved oxygen data for the tidal Schuylkill River for the period of sturgeon monitoring. The most recent data was collected by the Philadelphia Water Department (PWD 2015) using continuously recording sondes located 0.8 and 7.8 km upriver of the Delaware River confluence during the summers (July–September) of 2012 and 2013. PWD’s data showed that individual dissolved oxygen concentrations at the 0.8 km station (usable data were obtained only in 2013 at this station) ranged from ~3.8–9.6 mg/l (daily average ~4.9–7.9 mg/l), with most individual readings above 5 mg/l. Dissolved oxygen concentrations at the 7.8 km station ranged from ~4.0–10.0 mg/l (daily average ~4.8–8.9 mg/l), with most readings above 5.5 mg/l in 2012; and ~5.9–9.0 mg/l (daily average ~6.9–9.0 mg/l,), with most readings above 7 mg/l, in 2013 (PWD 2015). Secor and Niklitschek (2001) concluded that young-of-year Shortnose Sturgeon will experience lost production in habitats with <60% dissolved oxygen saturation, which corresponds to 4.3–4.7 mg/l at summertime temperatures (22–27C°), and observed lethal effects at dissolved oxygen concentrations ≤ 3.3 mg/l. Assuming that the dissolved oxygen concentrations observed by PWD (2015) in 2012 and 2013 are representative of prevailing conditions, dissolved oxygen levels in the tidal Schuylkill River appear to be generally suitable for Shortnose Sturgeon, particularly adults, which likely have a greater tolerance for low dissolved oxygen conditions than juveniles, although oxygen levels may transiently drop to stressful levels during periods of high water temperature and low fresh water inflow. The three Shortnose Sturgeon detected in the Schuylkill River may have been better adapted to transient low dissolved oxygen conditions since they were large fish and, based on Peake Urban Naturalist H.M. Brundage III 2021 No. 47 8 (2005), would have lower resting oxygen consumption rates than smaller individuals. The absence of detection of juvenile Shortnose or Atlantic sturgeons suggests that the Schuylkill River is not currently utilized by this life stage, although juveniles of both species occur in the adjacent Delaware River, particularly during the non-summer months (Brundage and O’Herron 2009; Hale et al. 2016; H. Brundage, ERC, Lewes, DE, unpubl. data). This may be the result of the juvenile sturgeon’s requirement for higher dissolved oxygen conditions. Shortnose Sturgeon are generally thought to inhabit deep, mainstem reaches of large coastal rivers (Bain 1997, Dadswell et al. 1984, Kynard et al. 2016), although Kieffer and Kynard (2012a, b), reported that some Shortnose Sturgeon may forage in the lower reaches of large tributaries of the Connecticut River. More recently, Hodgdon et al. (2019) identified the Saco River estuary, a proportionally small river flowing into the Gulf of Maine, as a seasonal foraging area for Shortnose Sturgeon. The pattern of occurrence of Saco River Shortnose Sturgeon, where the same individuals returned to the same river reaches over multiple years, is similar to what I observed in the Schuylkill River. Together, these studies suggest that tributaries and smaller river systems may serve a more important role in the life history of Shortnose Sturgeon than previously thought. Water quality improvement has allowed the return of a number of formerly extirpated fish species to the tidal Schuylkill River. Perillo and Butler (2009) identified 29 fish species in the tidal Schuylkill River, including the anadromous Alosa aestivalis Mitchill (Blueback Herring), Alosa mediocris Mitchill (Hickory Shad), Alosa pseudoharengus Wilson (Alewife), Alosa sapidissima Wilson (American Shad), and Morone saxatilis Walbaum (Striped Bass), which can now pass into the non-tidal river through a fishway constructed at Fairmount Dam. Other species that are now common in the tidal river include Carpiodes cyprinus LeSueur (Quillback), Catostomus commersonii Lacepède (White Sucker), Cyprinus carpio Linnaeus (Common Carp), Dorosoma cepedianum LeSueur (Gizzard Shad), Ictalurus punctatus Rafinesque (Channel Catfish), Micropterus dolomieu Lacepède (Smallmouth Bass), Morone americana Gmelin (White Perch), and the invasive Pylodictis olivaris Rafinesque (Flathead Catfish) (Perillo and Butler 2009). This study provides further evidence of the unique capabilities of acoustic telemetry for studying the occurrence and movements of aquatic animals (see reviews by Cooke et al. 2004, Crossin et al. 2017, and Hussey et al. 2015) and is an example of how acoustic tagging for specific projects can be leveraged to study other areas and address other topics. Longer-term investigation of the use of the tidal Schuylkill River, as well as other tributaries and small rivers, by sturgeons, combined with the collection of relevant water quality data, is encouraged. Acknowledgements Sturgeon monitoring in Schuylkill River was funded by Evergreen Resources Group, LLC. I thank Tiffani Doerr, of Evergreen, and Jenny Kachel and Jennifer Menges, of Stantec Consulting Services, Inc., for their interest and support. I also thank Tim Delk of Stantec and Sean Gorby of ERC for their assistance deploying and retrieving the acoustic receivers, and Glenn Curry of Stantec for preparing the receiver location figure. Finally, I thank two anonymous reviewers for their constructive comments on the manuscript. Literature Cited Bain, M.B. 1997. Atlantic and Shortnose Sturgeon of the Hudson River: Common and divergent life history attributes. Environmental Biology of Fishes 48:347–358. Bain, M.B., N. Haley, D.L. Peterson, K.K. Arend, K.E. Mills, and P.J. Sullivan. 2007. Recovery of a US Endangered Fish. PLoS ONE 2(1): e168. Urban Naturalist H.M. Brundage III 2021 No. 47 9 Bauers, S. 2014. Protected Shortnose Sturgeon found in Schuylkill. The Philadelphia Inquirer. Available online at https://www.inquirer.com/philly/health/science/20141104_Protected_shortnose_ sturgeon_found_in_Schuylkill.html. Accessed 1 August 2020. Brundage, H.M. 1986. Movement of pre- and post-spawning Shortnose Sturgeon (Acipenser brevirostrum) in the Delaware River. MS Thesis. University of Delaware, Newark, DE. 156 pp. Brundage, H.M. and R.E. Meadows. 1982. Occurrence of the endangered Shortnose Sturgeon, Acipenser brevirostrum, in the Delaware River. Estuaries 5:203–208. Brundage, H.M., and J.C. O’Herron. 2009. Investigations of juvenile Shortnose and Atlantic sturgeons in the lower tidal Delaware River. Bulletin of the New Jersey Academy of Science 54:1–8. Campbell, J.G. and L.R. Goodman. 2004. Acute sensitivity of juvenile Shortnose Sturgeon to low dissolved oxygen concentrations. Transactions of the American Fisheries Society 133:772–776. Chambers, R.C., D.D. Davis, E.A. Habeck, N.K. Roy, and I. Wirgin. 2012. Toxic effects of PCB126 and TCDD on Shortnose and Atlantic Sturgeon. Environmental Toxicology and Chemistry 31:2324–2337. Cooke, D. W., and S. D. Leech. 2003. Movements of shortnose sturgeon in the Santee Cooper lake system: Santee Cooper FERC Studies. South Carolina Department of Natural Resources, Bonneau, SC, USA. 34 pp. Cooke, S.J., S.G. Hinch, M. Wikelski, R.D. Andrews, T.G. Wolcott, and P.J. Butler. 2004. Biotelemetry: A mechanistic approach to ecology. Trends in Ecology and Evolution 19:334–343. Crossin, G.T., M.R. Heupel, C.M. Holbrook, N.E. Hussey, S.K. Lowerre-Barbieri, V.M. Nguyen, G.D. Raby, and S.J. Cooke. 2017. Acoustic telemetry and fisheries management. Ecological Applications 27:1031–1049. Dadswell, M.J., B.D. Taubert, T.S. Squires, D. Marchette, and J. Buckley. 1984. Synopsis of biological data on Shortnose Sturgeon, Acipenser brevirostrum LeSueur 1818. NOAA Technical Report, NOAA Fisheries 14. National Marine Fisheries Service, Gloucester , MA. 45 pp. DRBC (Delaware River Basin Commission). 1969. The Delaware River basin stream mileage system. Staff Paper 105, Revision 1. Trenton, NJ. Available online at https://www.state.nj.us/drbc/basin/ river-mileage-sys.html. Accessed 26 August 2021. ERC (Environmental Research and Consulting, Inc.). 2002. Contaminant analysis of tissues from two Shortnose Sturgeon (Acipenser brevirostrum) collected in the Delaware River. Final Report to the National Marine Fisheries Service. Environmental Research and Consulting, Inc., Kennett Square, PA, USA. 18 pp. ERC (Environmental Research and Consulting, Inc.). 2006a. Acoustic telemetry study of the movements of Shortnose Sturgeon in the Delaware River and Bay. Progress Report for 2003-2004. Prepared for NOAA Fisheries. Environmental Research and Consulting, Inc., Kennett Square, PA, USA. 20 pp. ERC (Environmental Research and Consulting, Inc.). 2006b. Final report of Shortnose Sturgeon population studies in the Delaware River, January 1999 through March 2003. Prepared for NOAA Fisheries. Environmental Research and Consulting, Inc., Kennett Square, PA, USA. 9 pp. ERC (Environmental Research and Consulting, Inc.). 2008. Final report of investigations of Shortnose Sturgeon early life stages in the Delaware River, spring 2007 and 2008. Prepared for NJ Division of Fish and Wildlife. Environmental Research and Consulting, Inc., Kennett Square, PA, USA. 24 pp. ERC (Environmental Research and Consulting, Inc.). 2010. Movements of acoustically-tagged Shortnose Sturgeon in the Delaware River and Bay during 2009. Prepared for NOAA Fisheries. Environmental Research and Consulting, Inc., Kennett Square, PA, USA. 9 pp. ERC (Environmental Research and Consulting, Inc.). 2015. Sturgeons in the mid-Atlantic region: A multi-state collaboration of research and conservation. Final report of: Identification of Shortnose Sturgeon spawning sites and characterization of early life stage habitat in the non-tidal Delaware River and distribution and habitat use of juvenile Atlantic Sturgeon in New Jersey waters. Prepared for the NJ Division of Fish and Wildlife, Endangered and Non-Game Species Program. Environmental Research and Consulting, Inc., Kennett Square, PA, USA. 31 pp. Urban Naturalist H.M. Brundage III 2021 No. 47 10 ERC (Environmental Research and Consulting, Inc.). 2018. Monitoring of acoustically tagged Shortnose Sturgeon in the vicinity of the Scudder Falls Bridge Replacement Project–Spring, 2018. Prepared for ACT Engineers, Inc. SBE. Environmental Research and Consulting, Inc., Kennett Square, PA, USA. 13 pp. ERC (Environmental Research and Consulting, Inc.). 2020. Report of sturgeon monitoring and protection during rock removal, Delaware River Main Channel Deepening Project, December 2019– February 2020. Prepared for Great Lakes Dredge and Dock Co., LLC. Environmental Research and Consulting, Inc., Kennett Square, PA, USA. 39 pp. Ettinger, W.S. 1982. Macrobenthos of the freshwater tidal Schuylkill River at Philadelphia, Pennsylvania. Journal of Freshwater Ecology 1:599–606. Hale, E.A., I.A. Park, M.T. Fisher, R.A. Wong, M.J. Stangl, and J.H. Clark. 2016. Abundance estimate for and habitat use by early juvenile Atlantic Sturgeon within the Delaware River estuary. Transactions of the American Fisheries Society 145:1193–1201. Hastings, R.W., J.C. O’Herron, K. Schick, and M. Lazzari. 1987. Occurrence and distribution of Shortnose Sturgeon, Acipenser brevirostrum, in the upper tidal Delaware River. Estuaries 10:337–341. Hodgdon, C.T., C. Tennenhouse, W.Y. Koh, J. Fox, and J.A. Sulikowski. 2019. Shortnose Sturgeon (Acipenser brevirostrum) of the Saco River estuary. Journal of Applied Ichthyology 35:30–37. Hussey, N.E., S.T. Kessel, K. Aarestrup, S.J. Cooke, P.D. Cowley, A.T. Fisk, R.G. Harcourt, K.N. Holland, S.J. Iverson, J.F. Kocik, J.E. Mills Flemming, and F.G. Whorisky. 2015. Aquatic animal telemetry: A panoramic window into the underwater world. Science 348:6240. IUCN (International Union for the Conservation of Nature). 2020. The IUCN red list of threatened species. Version 2020-2. Available online at https://www.iucnredlist.org. Accessed 25 August 2021. Jarvis, P.L., J.S. Ballantyne, and W.E. Hogans. 2001. The influence of salinity on the growth of juvenile Shortnose Sturgeon. North American Journal of Aquaculture 63:272–276. Jenkins, W.W., T. Smith, L. Heyward, and D.M. Knott. 1993. Tolerance of Shortnose Sturgeon, Acipenser brevirostrum, juveniles to different salinity and dissolved oxygen concentrations. Proceedings of the Annual Conference of the Southeastern Association of Fish and Wildlife Agencies 47:476–484. Kahn, J. and M. Mohead. 2010. A protocol for use of Shortnose, Atlantic, Gulf, and Green sturgeons. U.S. Dept. of Commerce, NOAA Tech. Memo. NMFS-OPR-45. 62 pp. Kauffman, G.J., A.R. Homsey, A.C. Belden, and J.R. Sanchez. 2011. Water quality trends in the Delaware River Basin (USA) from 1980 to 2005. Environmental Monitoring and Assessment 177:193–225. Kieffer, M.C. and B. Kynard. 2012a. Wintering of Connecticut River Shortnose Sturgeon. Pp. 129– 163, In B. Kynard, P. Bronzi, and H. Rosenthal (Eds.). Life History and Behaviour of Connecticut River Shortnose and Other Sturgeons. World Sturgeon Conservation Society Special Publication No. 4. Books on Demand, Norderstedt, Germany. 320 pp. Kieffer, M.C. and B. Kynard. 2012b. Long-term evaluation of telemetry tagging on Shortnose Sturgeon. Pp. 297–320, In B. Kynard, P. Bronzi, and H. Rosenthal (Eds.). Life History and Behaviour of Connecticut River Shortnose and Other Sturgeons. World Sturgeon Conservation Society Special Publication No. 4. Books on Demand, Norderstedt, Germany. 320 pp. Kocan, R.M., M.B. Matta, and S.M. Salazar. 1996. Toxicity of weathered coal tar for Shortnose Sturgeon (Acipenser brevirostrum) embryos and eggs. Archives of Environmental Contamination and Toxicology 31:161–165. Kreeger, D., A. T. Padeletti, and D. C. Miller. 2010. Delaware estuary benthic inventory (DEBI). An exploration of what lies beneath the Delaware Bay and River. PDE Report No. 11-06. Partnership for the Delaware Estuary, Wilmington, DE, USA. 71 pp. Kynard, B. 1997. Life history, latitudinal gradients, and conservation of Shortnose Sturgeon Acipenser brevirostrum. Environmental Biology of Fishes 48:319–334. Kynard, B., S. Bolden, M. Kieffer, M. Collins, H. Brundage, E. Hilton, M. Litvak, M. Kinnison, T. King, and D. Peterson. 2016. Life history and status of Shortnose Sturgeon (Acipenser brevirostrum). Journal of Applied Ichthyology 32 (Suppl. 1): 208–248. Matsche, M.A., K.M. Rosemary, H.M. Brundage, and J.C. O’Herron. 2012. Reproductive demographics, intersex, and altered hormone levels in Shortnose Sturgeon Acipenser brevirostrum from the Delaware River, USA. Journal of Applied Ichthyology 29:299–309. Urban Naturalist H.M. Brundage III 2021 No. 47 11 McConnell, C. and R.C. Chambers. 2018. The combined effects of hypoxia and contaminants on the early life stages of Shortnose Sturgeon, Acipenser brevirostrum. Pp. VII-1 through VII-23, In D.J. Yozzo, S.H. Fernald, and H. Andreyko (Eds.). Final reports of the Tibor T. Polgar Fellowship Program 2015. Hudson River Foundation, NY, USA. 23 pp. Moberg, T. and M. DeLucia. 2016. Potential impacts of dissolved oxygen, salinity, and flow on successful recruitment of Atlantic Sturgeon in the Delaware River. The Nature Conservancy. Harrisburg, PA, USA. 26 pp. Monosson, E. 1997. Reproductive and developmental effects of contaminants in fish populations: Establishing cause and effect. Pp. 177–194, In R.M. Rolland, M. Gilbertson, and R.E. Peterson (Eds). Chemically Induced Alterations in Functional Development and Reproduction in Fishes. Proceeding of a Session at the Wingspread Conference Center, July 21–23, 1995, Racine, WI. SETAC Press, Pensacola, FL. 194 pp. O’Herron, J.C., K.W. Able, and R.W. Hastings. 1993. Movements of Shortnose Sturgeon, Acipenser brevirostrum, in the Delaware River. Estuaries 16:235–240. Peake, S.J. 2005. Swimming and respiration. Pp. 147-166, In G.T.O LeBreton, F.W.H. Beamish, and R.S. McKinley (Eds.). Sturgeons and Paddlefish of North America. Kluwer Academic Publishers, Dordrecht, Netherlands. 323 pp. Perillo, J.A. and L.H. Butler. 2009. Evaluation of the Fairmount Dam fish passage facility with application to anadromous fish restoration in the Schuylkill River, Pennsylvania. Proceedings of the Pennsylvania Academy of Science 83:24–33. PWD (Philadelphia Water Department). 2015. Tidal water quality model–bacteria and dissolved oxygen. Consent Order and Agreement Deliverable IX and X. City of Philadelphia combined sewer overflow long term control plan update. Submitted to the Commonwealth of Pennsylvania Department of Environmental Protection. Philadelphia Water Department, Philadelphia, PA. 138 pp. Secor, D.H. 2015. Migration Ecology of Marine Fishes. Johns Hopkins University Press, Baltimore, MD, USA. 292 pp. Secor, D.H. and T.E. Gunderson. 1998. Effects of hypoxia and temperature on survival, growth, and respiration of juvenile Atlantic Sturgeon, Acipenser oxyrinchus. Fishery Bulletin 96:603–613. Secor, D.H. and E.J. Niklitschek. 2001. Sensitivity of sturgeons to environmental hypoxia: A review of physiological and ecological evidence. Pp. 61–78, In R. V. Thurston (Ed.). Fish Physiology, Toxicology, and Water Quality. La Paz, Mexico, January 22–26, 2001. Available at http://aquaticcommons. org/4821. Accessed 1 August 2020. Sih, A. and A.M. Bell. 2008. Insights for behavioral ecology from behavioral syndromes. Advances in the Study of Behavior 38:227–281. Stevenson, W.L. 1914. Examination of river bottoms at Philadelphia. American Journal of Public Health. 4:1072–1078. Vladykov, V.D. and J.R. Greeley. 1963. Order Acipenseroidei. Pp. 24-60, In V.H. Olsen, (Ed.). Fishes of the Western North Atlantic. Part 3: Soft-Rayed Bony Fishes. Sears Foundation for Marine Research, Yale University, New Haven, CT, USA. 630 pp.