2007 NORTHEASTERN NATURALIST 14(4):531–544 An Evaluation of the Ichthyofauna of the Bronx River, a Resilient Urban Waterway Joseph W. Rachlin1,*, Barbara E. Warkentine1,2, and Antonios Pappantoniou1 Abstract - Fish were sampled from the entire 34.4-km Bronx River each year from 2001 to 2005 inclusive, yielding a database of 4000 fi sh com pris ing 23 freshwater species and 22 estuarine species. These data were compared to the historic data from 1936–1998 as recorded in the New York State De part ment of Environmental Conser va tion’s digital database, Albany, NY. Only 6 freshwater species reported in the his tor ic data—Rhodeus sericeus (Bitterling), Salmo trutta (Brown Trout), Semotilus corporalis (Fallfi sh), Esox americanus vermiculatus (Grass Pickerel), Etheostoma nigrum (Johnny Dart er), and Esox lucius (Northern Pike)—are no longer in the river. However, the original report of the presence of the Johnny Darter probably resulted from taxonomic con fu sion since this species has never been in the Hudson Valley, and we strongly believe that the report of the presence of grass pickerel is also the result of misidentifi cation of the specimen for the same reason as given for the johnny darter. The report of the Brown Trout should be dis count ed since this species has been only taken in the Bronx River following a stocking event. We have found a breeding population of Brown Trout in the southern end of Davis Brook, but these have not yet traversed the multi-channel marsh area to enter the Bronx River proper. Therefore, only three pre vi ous ly reported species—Bitterling, Fallfi sh, and Northern Pike— are no longer in the river. Four spe cies—Fundulus diaphanus (Band ed Kil li fi sh), Ameiurus nebulosus (Brown Bull head), Apeltes quadracus (Fourspine Stick le back), and Micropterus dolomieu (Small mouth Bass)—not re port ed in the historic database were part of our 2001–2005 freshwater collection. These discrepancies are ex plained, and on balance, it was determined that for the past 70 years, the Bronx River has been remarkably stable in terms of fi sh species and diversity. Ex am i na tion of the estuarine portion of the river shows that it func tions as an important nursery ground for many com mer cial and rec re ation al fi sh harvested from New York waters. Introduction The impact of urbanization on river systems has been well doc u ment ed (Gerhard et al. 2004, Limburg et al. 2005). As a result of increased amounts of domestic and/or industrial waste, sed i ment load, and trash, many urban rivers have shown degradation in water quality, decrease in species di ver si ty, and change in the faunal composition over time (Shepp and Cummins 1977). The loss of riparian vegetation, due to the development of roadways and industrial complexes adjacent to wa ter ways, has con trib ut ed to in creased water temperatures and loss of habitat for fi sh (Nislow 2005). In recent 1Laboratory for Marine and Estuarine Research (La MER), Department of Biological Sciences, Lehman College, 250 Bedford Park Boulevard West, Bronx, NY 10468- 1589. 2Science Department, SUNY Maritime College, 6 Pennyfi eld Avenue, Bronx, NY 10465-4198. *Corresponding author - joseph.rachlin@lehman.cuny.edu. 532 Northeastern Naturalist Vol. 14, No. 4 years, signifi cant attention has been focused on the plight of aquatic systems in the face of urban sprawl (Brown et al. 2005). As a result of this attention, many rivers and streams have been designated as primary sites for cleanup and restoration. In 1992, the New York State Department of En vi ron men tal Conservation, which is responsible for monitoring the “health” of over 900 rivers and streams throughout the State, incorporated the Bronx River into its monitoring program (Bode et al. 2004). The Bronx River, a 34.4-km urban river, fl ows from its current source at Davis Brook, Valhalla, NY, south to its mouth between Clason and Hunts Points on the East River, at the extreme western end of Long Island Sound (Fig. 1). For the fi rst 22.3 km of its course, the river passes through a suburban and lightly urbanized landscape, essentially following the Bronx River Parkway, America’s fi rst scenic parkway. In many communities along this 22.3-km reach, the river has been incorporated, by means of small im poundments, into village and town parks. During construction of the Bronx River Parkway, between 1916 and 1925, the river was re-channeled and straightened so that it would parallel the course of the parkway and reduce fl ooding, which was a signifi cant problem due to the original sinuous course of the river in Westchester County. The last section of the Parkway was begun in 1931 near East 233rd Street in the Bronx and was completed in the fall of 1960, and the section of the river paralleling the parkway in the Bronx was also modifi ed and in places re-channeled. In this last 12.1 km, the river enters New York City and fl ows through an ever more densely ur ban ized area. As it enters the city, the river fi rst traverses a section known as the shoelace, with reduced bank forest cover and poor bank stabilization, then proceeds through a restored section known as the Bronx Forest before it enters sequentially the grounds of the New York Botanical Garden (NYBG) and the Wildlife Conservation Society’s Bronx Zoo (WCS). In the section of the river within the NYBG and WCS properties, the river fl ows over three major dams built at their current sites between 1845 and the early 1850s; the 182nd Street Dam, the southern-most of the three, was built in the early colonial period by the De Lancey family (Bolton 1948, Comfort 1906). The northernmost of these, within the grounds of NYBG, is a 2.1-m dam at the Snuff Mill at rkm 7.2 (river mile 4.5), followed by a 4.3-m Twin Dam Complex at rkm 6.3 (river mile 3.9) within the grounds of WCS, and then the river cascades over a 5.5- m dam at the southern end of the WCS property at 182nd Street (rkm 4.8, river mile 3.0). Below this last intact dam, the river becomes tidally infl uenced and more estuarine as it fl ows southward, and its banks are heavily urbanized and industrialized. It was our goal to study the fishes of both the freshwater and estuarine sections of this urban river and to compare its species composition with past reports of ichthyofaunal data for the Bronx River, derived from the Historic Distribution of Inland Fishes of New York State (Carlson 2001), the com pre hen sive study of the status of fish in New York State (Carlson 2007 J.W. Rachlin, B.E. Warkentine, and A. Pappantoniou 533 and Daniels 2004), and the 1984 report of Bronx River fishes (Schmidt and Samaritan 1984). The historic database (Carlson 2001, Carlson and Daniels 2004) has records for the years 1936, 1954, 1957, 1986, and 1998, and covers the river from rkm 9.0 (river mile 5.6)–rkm 31.7 (river mile 19.7). This database lists a total of 21 species of freshwater fish Figure 1. Map of the Bronx River from its source in Davis Brook to its mouth at the East River between Hunts Point and Clason Point, New York, NY. Station locations marked with an X, followed by the station number. 534 Northeastern Naturalist Vol. 14, No. 4 (Table 1). The study by Schmidt and Samaritan (1984) listed a total of 17 species of which only two—Notropis hudsonius (Clinton) (Spottail Shiner) and Cyprinus carpio Linnaeus (Common Carp)—were not reported in the historic da ta base, bringing the total reported species number for the freshwater reach of the Bronx River to 23. The finding of Spottail Shiner in the Bronx River was first reported in 1982 (Samaritan and Schmidt 1982). Our current study of the ichthyofauna of this river began in 2001, and continued an nu al ly through 2005. Methods For our sampling protocol, we established a series of stations along the length of the river from its source in Davis Brook to its mouth at buoy markers 5 and 6 between Hunts and Clason Points (Fig. 1). The nine freshwater stations consisted of: Station 1 at Davis Brook (rkm 34.4, river mile 21.4), now the source of the Bronx River; Station 2 (rkm 33.3, river mile 20.7); Station 3 (rkm 31.2, river mile 19.4); Station 4 (rkm 21.9, river mile 13.6); Station 5 (rkm 16.9, river mile 10.5); Station 6 (rkm 12.1, river mile 7.5) at Nereid Avenue at the border between Bronx and Westchester Counties; Station 7 (rkm 6.8, river mile 4.2) within the New York Botanical Garden just south of the Snuff Mill Dam; Station 8 (rkm 6.3, river mile 3.9) within the Wildlife Conservation Society’s Bronx Zoo just south of the Twin Dam Complex; and Station 9 (rkm 4.5, river mile 2.8) in the West Farms Section of the river, where the river, being south of the 182nd Street Dam, is tidally influenced but still essentially freshwater. The four estuarine stations were: Station 10 (rkm 1.8, river mile 1.1); Station 11 (rkm 0.3, river mile 0.2), Station 12 at Clason Point (a marine, shore based station in the East River, south of the mouth of the Bronx River); and Station 13, the Federal Channel, which runs from the mouth (rkm 0, river mile 0) north to Station 10. Each of the sampling stations 1–9 was sampled over a length of 150 m at each visit. The distances, north from the mouth of the river, given for each station are at the midpoint of this 150-m run. Stations 10, 11, and 12 were sampled over a 50-m run at each visit; again the distance given is for the midpoint of each sampling run. Station 13, the Federal Channel, was sam pled by trawl over the entire 1.8-km distance between the mouth and Station 10 at each sampling event. Sampling in the freshwater reaches of the river was conducted using 1.22-m2 fi ne-mesh (0.32-cm, stretched nylon mesh) seines. On fi ve oc casions, one each in March 2005 at Station 5, in May 2005 at Station 6, and in June 2005 at Station 4, and twice in April 2005 at Stations 1 and 5, when conductivity was appropriate, a Smith-Root backpack electro-shocker was employed to supplement the seine sampling. Sampling in the Federal Channel was accomplished using a benthic shrimp trawl, 3.3 m wide with 3.8-cm 2007 J.W. Rachlin, B.E. Warkentine, and A. Pappantoniou 535 stretch mesh #9 nylon body and 3.3-cm stretch mesh #15 nylon cod end (Nylon Net Co., Memphis, TN), operated from the stern deck of a 14.02-m buoy-tender chartered from SUNY Maritime College, Bronx, NY. The net was towed for sequential 10-minute tows at a speed of one knot, traveling both north and south at each sampling visit. Tow line, between the stern deck of the vessel and the “doors” of the net, was 28 m to insure that the net fi shed at the bottom. The 2.0-m mean low water depth of the Federal Channel is maintained by the US Army Corps of Engineers. Other shore-based stations in the estuary or adjacent East River were sampled using the same seines as in the freshwater reaches of the river, and minnow traps supplemented this sampling; traps were left to soak for 2 hrs. Since each collecting day occupied the same amount of time on station, regardless of which station was being sampled or the gear used, we designated each collection date as a unit of effort and were therefore able to compute “catch per unit effort” to gain a sense of the relative abundance of each species by station (Table 1). The sampling protocol of our 13 sampling stations was designed so that each station was visited at least once per month during the sampling season. All sampling was conducted between March and September of each year (2001–2005) to be consistent with and overlap the sampling periods in the historic data base (Carlson 2001, Carlson and Daniels 2004) for the Bronx River. These periods in the historic data base were: July, for the 1936 data at rkm 10.0–31.7; July, for the 1954 data at rkm 31.1; June–July, for the 1957 data at rkm 24.8–31.1; September, for the 1986 data at rkm 22.1–31.1; and September, for the 1998 data at rkm 9.0–27.8. All of the New York State historic data (Carlson 2001, Carlson and Daniels 2004) for the Bronx River are presented as species presence in our Table 1. Results From 2001 through 2005, we documented a total of 4000 fi sh comprising 23 species from the freshwater section and 22 from the estuarine section (Table 1), for a total of 45 species; two species, Apeltes quadracus (Mitchill) (Fourspine Stickleback) and Fundulus heteroclitus (Linnaeus) (Mummichog) were found in both zones. We do, however, know that Anguilla rostrata (Lesueur) (American Eel), being catadromous, would also be in the estuary, although it was not taken by our sampling at Stations 10–13. Not included in Table 1, but for completion, we mention that one specimen each of Alosa aestivalis (Mitchell) (Blueback Herring), in December 2002, and Alosa mediocris (Mitchell) (Hickory Shad), in October 2002, were taken by hook and line at Hunts Point just south of the mouth of the Bronx River by local fi sherman and deposited in our laboratory collection. A careful examination of Table 1 shows that of the 23 species of fresh wa ter fi sh listed, only Rhodeus sericeus (Pallas) (Bitterling), Semotilus corporalis Mitchill (Fallfi sh), Etheostoma nigrum Rafi nesque (Johnny Dart er), Esox 536 Northeastern Naturalist Vol. 14, No. 4 Table 1. Catch per unit effort for fi sh species collected from 13 stations in the Bronx River, years 2001–2005, and occurrence of fi sh species, as re port ed in the New York State De part ment of Environmental Con ser va tion’s digital database, Albany, NY by year and as collected in this current study, are designated by an X. Station designations Collection years 2001– Species 1 2 3 4 5 6 7 8 9 10 11 12 13 1936 1954 1957 1986 1998 2005 Ameiurus nebulosus 0.3 1.0 1.0 X Anguilla rostrata 0.3 9.8 X X Apeltes quadracus 2.0 3.3 35.5 0.4 0.1 X Carassius auratus (L.) (Goldfi sh) 1.0 X X Catastomus commersoii 13.3 30.3 19.0 27.3 34.5 7.0 12.3 X X X X X X Cyprinus carpio 0.3 0.8 0.7 X Esox americanus americanus 0.3 X E. americanus vermiculatus X E. lucius X Etheostoma nigrum X E. olmstedi 4.7 9.0 27.0 2.0 2.5 6.0 7.5 28.0 X X X X X Fundulus diaphanus 0.5 0.5 X F. heteroclitus 0.3 7.3 6.8 7.0 12.8 0.5 65.6 X X X Gambusia affi nis 0.3 X Lepomis auritus (L.) (Redbreast Sunfi sh) 6.7 0.5 5.5 X X L. gibbosus (L.) (Pumpkinseed) 2.7 0.3 0.3 0.5 X X X L. macrochirus Rafi nesque (Bluegill 0.3 0.5 0.5 1.3 X X Sunfi sh) Luxilus cornutus (Mitchill) 0.5 X X Micropterus dolomieu 0.7 X M. salmoides (Lacépedè) (Largemouth 2.0 2.3 0.5 0.7 1.0 X X X Bass) Notemigonus crysoleucas (Mitchill) 1.0 X X X (Golden shiner) Perca fl avescens (Mitchill) 0.7 1.0 X X (Yellow Perch) Pimephales promelas Rafi nesque (Fathead 0.5 2.7 0.8 X X Minnow) 2007 J.W. Rachlin, B.E. Warkentine, and A. Pappantoniou 537 Table 1, continued. Station designations Collection years 2001– Species 1 2 3 4 5 6 7 8 9 10 11 12 13 1936 1954 1957 1986 1998 2005 Rhinichthys atratulus 23.3 0.3 25.0 4.8 5.0 2.0 0.3 2.3 X X X X X X Rhodeus sericeus X Salmo trutta 2.0 X X X X Semotilus atromaculatus (Mitchill) 0.7 X X S. corporalis X Anchoa mitchilli (Valenciennes) (Bay 7.7 1.9 0.9 X Anchovy) Archosargus probatocephalus (Walbaum) 0.1 X (Sheepshead) Brevoortia tyrannus 11.0 1.0 X Cynoscion regalis 0.1 0.7 X Dorosoma cepedianum (Lesuer) (Gizzard Shad) 0.2 X Gobiosoma bosc 0.4 X G. ginsburgi 0.1 X Menidia menidia 55.6 72.8 0.9 1.4 X Microgadus tomcod 0.1 X Morone saxatilis 0.8 3.3 X Myoxocephalus aenaeus (Mitchill) (Grubby) 0.1 0.3 X Paralichthys dentatus 0.1 X Peprilus triacanthus (Peck) (Butterfi sh) 0.3 X Pholis gunnellus 0.1 X Pomatomus saltatrix 0.1 X Prionotus carolinus (L.) (Northern Searobin) 0.1 X Pseudopleuronectes americanus 3.9 1.0 0.4 1.1 X Syngnathus fuscus Storer (Northern Piperfi sh) 0.1 X Tautogolabrus adspersus 0.1 X Urophycis regia (Walbaum) (Spotted Hake) 0.3 X 538 Northeastern Naturalist Vol. 14, No. 4 lucius Linnaeus (Northern Pike), and Esox americanus vermiculatus Lesueur (Grass Pickerel) were not part of the 2001–2005 col lec tion. But the 2001– 2005 collection included Ameiurus nebulosus (Lesueur) (Brown Bullhead), fourspine stickleback, Cyprinus carpio (Common Carp), Esox americanus americanus Gmelin (Redfi n Pickerel), Fundulus diaphanus (Lesueur) (Banded Killifi sh), Gambusia affi nis (Baird and Girard) (Western Mosquitofi sh), and Micropterus dolomieu Lacépède (Smallmouth Bass), which are absent from the historic database. The estuarine species listed in Table 1–those collected from Stations 10–13 (Fig. 1)–represent the fi rst time that a species list for the estuarine portion of the Bronx River has been compiled; it includes 22 species. Thus the current total fi sh species count, both freshwater and es tu a rine, consists of 45 species with mum mi chog, fourspine stickleback, and American eel being found in both zones of the Bronx River. Table 1 also shows the catch-per-unit-effort data for the 2001–2005 collection for both the freshwater and estuarine portions of the river. The southernmost portion of Station 9 (rkm 4.5, river mile 2.8; Fig. 1) represents the northern-most excursion of measurable salinity (0.5 ppt) during summer low-fl ow periods, although the tidal pulse is felt as far north as 180th Street (rkm 4.7, river mile 2.9) during spring tides (Larson et al. 2004, Rachlin 2005). These “catch-per-unit-effort” data provide an indication of the rel a tive abundance of fi sh species by station, and their lateral distribution throughout the system. It can be seen (Table 1) that in the freshwater reaches of the river, Etheostoma olmstedi Storer (Tessellated Darter) is the most widely distributed fi sh with a range extending from Station 1 in the north to Station 9 in the south (Fig 1). The next two most widely distributed species are Rhinichthys atratulus (Hermann) (Blacknose Dace), whose range also extends from Station 1 south to Station 9, and Mummichog, which is found from Station 4 (Fig. 1) in the north to and throughout the estuary, except in the Federal Channel (Station 13). All other species have more restricted ranges (Table 1). By summing the catch-per-unit-effort data for a species across all sta tions from which that species was collected (Table 1), one gets an estimate of its relative abundance in the river. From the point of view of overall abundance in the river as a whole, Catostomus commersoii (Lacépède) (White Sucker) is the most abundant species, followed by Menidia menidia (Linnaeus) (Atlantic Silverside), which is restricted to the estuarine portion of the river. Next in abundance is Mummichog, followed in order by Tessellated Darter, Blacknose Dace, and Fourspine Stickleback. None of the other fi sh species, in either the freshwater or estuarine sections of the river, approach the catchper- unit-effort values of these species. Discussion Examination of the data presented in Table 1 shows a remarkable consis ten cy in the majority of fi sh species in the Bronx River from the period 2007 J.W. Rachlin, B.E. Warkentine, and A. Pappantoniou 539 1936 through 2005. This would indicate that over this 70-year period, the river, from the point of view of its ichthyofaunal content and diversity, has re mained as a relatively resilient aquatic environment in spite of occasional episodes of anthropogenic pollution resulting from combined sewage outfl ows (CSOs) and industrial spills from the various communities through which the river fl ows. There are, however, a few species that were present in the historic database, but are no longer found in the river. The fi rst missing species is Semotilus corporalis Mitchill (Fallfi sh), re port ed in the 1936 collection between rkm 9.98–31.7 (river mile 6.2–19.7), and then disappearing from all subsequent collections. It had been speculated that poor water quality in the Bronx River caused the elimination of this species (Schmidt and Samaritan 1984); however, it is possible, since these fi sh readily take a fl y lure and have been, on occasion, the object of a recreational fi shery (Werner 2004), that a relatively marginal population was simply overfi shed. This explanation has some support since the Bronx River in this region has often been stocked with Salmo trutta Linnaeus, (Brown Trout) to support a recreational fl y fi shery, and these animals (Fall fi sh) could have been taken along with the trout. Further, we found no meaningful degradation in habitat or water quality (Rachlin 2005) in this stretch of the river to account for the extirpation of this species. Additional support for this idea is the fact that Blacknose Dace have been associated with the same habitats favored by Fallfi sh and have even been reported to spawn on Fallfi sh nests (Smith 1985). However, elimination of the Fallfi sh due to sensitivity to pollutants and/or poor water quality, post 1936, can not be explicitly ruled out. Our data in di cate that populations of Blacknose Dace show good representation in the river from Station 1 south to Station 9 (Fig 1, Table 1). Brown trout reported in the 1954, 1957, and 1986 collections from rkm 22.0–31.1 (river mile 13.7–19.3) were the result of seasonal stocking, and never established themselves as a breeding population in the Bronx River. We did, however, fi nd a breeding population in the southernmost reaches of Davis Brook (Station 1) just south of Valhalla, NY, which is adjacent to the Kensico Reservoir (Fig 1). From here, Davis Brook opens into a multichannel marsh before coalescing again into a single stream, which at this point is called the Bronx River. This marsh area serves as an effective barrier preventing the downstream migration of the trout. We have never collected any trout south of this marsh area. The next fish to be considered is the Johnny Darter, reported once in the 1954 collection from rkm 31.1 (river mile 19.3) and never reported again from any section of the Bronx River. This fish, found in streams and rivers of the western drainages in New York State (Smith 1985, Werner 2004), is typically not part of the fauna of the Bronx River. However, the more characteristic Tessellated Darter can easily be confused with the Johnny Darter, especially during the breeding season when the males become quite dark, obscuring the lateral V, W, or X markings used to quickly distinguish 540 Northeastern Naturalist Vol. 14, No. 4 between these two species. Since the Tessellated Darter is common in and ranges throughout the freshwater reaches of the Bronx River, it is reasonable to assume, given the known distribution of the Johnny Darter, that the reported occurrence of this species in the 1954 collection could have re sult ed from a misidentification. Equally problematical is the report of Grass Pickerel in the 1957 col lec tion between rkm 24.8 and 31.1 (river mile 15.4–19.3), and our finding of Redfin Pickerel at our Station 2 (rkm 33.3, river mile 20.7) in es sen tial ly the same stretch of river. These subspecies of Esox americanus Gmelin (Pick er el) are very difficult to tell apart, especially in their ju ve nile stages, which are the stages captured in both studies. It is quite possible that the 1957 report represents a misidentification; we are rea son ably certain of our iden ti fi ca tion, having used the characteristics dis cussed by Crossman (1966), Smith (1985), and Werner (2004). Based on Crossman’s taxonomic study of Pickerel in eastern North America, using 13 morphological characters and including distribution maps of Redfin Pickerel, Grass Pickerel, and their intergrades (Crossman 1966), it seems very unlikely that Grass Pickerel, which in New York State is found only in the central and western parts of the state, would be, or ever had been, in the Bronx River. There is also some question regarding the taxonomic status of these subspecies and therefore, it is best to simply state that Pickerel is found in this section of the river. The presence of Northern Pike, only reported once in the 1954 collection from the same section of the river as Pickerel, and its absence from all other col lec tions, including our current survey, cannot be explained; nor do we have an explanation for the absence of Spottail Shiner, reported by Schmidt and Samaritan (1984) but not collected by us nor reported in the historic database (Carlson 2001, Carlson and Daniels 2004) for the Bronx River. The only other fish that has been extirpated from the river is Bitterling. This fish, common in northern Europe and central and north east ern Asia, was probably introduced into the United States in the early 1920s (Smith 1985, Werner 2004); at various times it has been reported from both the Bronx and Sawmill rivers in New York State (Carlson 2001, Schmidt and Samaritan 1984, Smith 1985, Werner 2004). Although reported in the 1936 collection, Schmidt and Samaritan (1984) last re port ed it from the Bronx River in 1979, and we had collected three spec i mens from the river at Paxton Avenue (rkm 16.9, river mile 10.5) in 1981. No collections since that date have ever reported finding Bitterling, and one of us (A. Pappantoniou), who has recently collected in the Saw mill River, also reports the absence of Bitterling from that river. This fish requires the presence of a unionid mussel in order to complete its life cycle because it, by obligation, deposits its eggs into the mantle cavity of these mussels (Breeder 1933, Przybylski and Garcia-Berthou 2004). It had been suggested that the assumed “demise” of unionid mus sels from the river, due to pollution, 2007 J.W. Rachlin, B.E. Warkentine, and A. Pappantoniou 541 might have accounted for the Bitterling’s ex tinc tion. Schmidt et al. (1981) speculated that the Bitterling, which was last seen in the Sawmill in 1951, continued to exist as a marginal pop u la tion in a small 1.2-km stretch of the Bronx River in the vicinity of Paxton Avenue where there were small populations of the unionid mussel Pyganodon cataracta (Say), with which the Bitterling had been as so ci at ed. Since populations of this unionid mussel, specimens of which are quite large (between 7.46–13.87 cm in length), are currently found at an av er age population density of 1.4 mussels/m2 in the Paxton Avenue section of the Bronx River just south of its confluence with the Sprain Brook, we believe that the absence of Bitterling cannot be ex plained by the assumed “absence” of these mussels; instead we suggest that by the late 1950s for the Sawmill and by the late 1980s for the Bronx River, these marginal pop u la tions of Bitterling were no longer able to sustain themselves and went extinct in these rivers. Based on the current presence of a total of 23 species of fish in the freshwater reaches of the Bronx River (Table 1), and the fact that the majority of these species have been part of the historic data base of ich thy o fau na for the river since 1936 (Table 1), we conclude that this river has been remarkably stable in terms of its fish species for the past 70 years. The species do represent, for the most part, stress-tolerant forms (Schmidt and Samaritan 1984), which is what one would expect from an urban river flowing through communities with zones of light industry, residential ar eas, and community parks at various distances from its banks. The pres ence in our collections of Fourspine Stickleback, Brown Bullhead, Banded Killifish, and Smallmouth Bass, which were not reported in the historic data base (Table 1), do not necessarily represent new introductions into the river. Rather, it likely reflects that the historic database consists of col lec tions made at intermittent times and was not the result of intensive surveys. Our sampling, conducted in each collecting season (March through Sep tem ber) from 2001 to 2005, and using a variety of sampling gear, was an intensive survey. An examination of Table 1 shows a community of 22 marine and es tu a rine fish species, many of which are important to the commercial and recreational fisheries of New York. Among these are American Eel, Brevoortia tyrannus (Latrobe) (Atlantic Menhaden), Cynoscion regalis (Bloch and Schneider) (Weakfish), Microgadus tomcod (Waldbaum) (Atlantic Tom cod), Morone saxatilis (Waldbaum) (Striped Bass), Paralichthys dentatus (Linnaeus) (Summer Flounder), Pomatomus saltatrix (Linnaeus) (Bluefish), Pseudopleuronectes americanus (Waldbaum) (Winter Flounder), and Tautogolabrus adspersus (Waldbaum) (Cunner). Since the majority of these species are found in the Bronx River Estuary in their juvenile to young-adult stages, it is clear that this estuary serves as an important nursery ground for these species. If we consider the estuary proper to begin just south of Drew Garden (rkm 4.34, river 542 Northeastern Naturalist Vol. 14, No. 4 mile 2.7) at the southern end of Station 9 (Fig 1), and to extend south to the river’s mouth on the East River, then our sampling stations from Station 10 (rkm 1.8, river mile 1.1) and south including the Federal Channel (Station 13) are in the heart of the estuary. Catch-per-unit-effort data (Table 1) shows that the most abundant species in the estuary are Atlantic Silverside and Mummichog, both of which serve as a food resource for many of the commercially and recreationally important fish species listed above. Among the least abun dant species in the estuary were Gobiosoma bosc (Lacépède) (Naked Goby), Gobiosoma ginsburgi Hildebrand and Schroeder (Seaboard Goby), Paralichthys dentatus (Summer Flounder), Pomatomus saltatrix (Bluefish), and Pholis gunnellus (Linnaeus) (Rock Gun nel). The low values for Summer Flounder and Bluefish can be explained by the fact that these are seasonal migrants into the area, and both of these species were taken only at Clason Point and in the Federal Channel near the mouth of the river. The Seaboard Goby was also taken from the Federal Channel, but was found in tires brought up by our trawl net, and thus are easily missed. The Rock Gunnel also was taken in the Federal Channel, and the Naked Goby was collected by seine at Station 10. These last two species represent first records for their presence in the Bronx River Estuary, and as such, the specimens have been forwarded to the ichthyological collection at the New York State Museum at Albany for cataloging; their catalogue numbers are NYSM 57943 for Naked Goby, and NYSM 58903 for Rock Gunnel. Together, the total of 45 fish species throughout the entire extent of the Bronx River and its estuary justifies the continuing efforts of organizations in the Bronx and Westchester counties to continue their efforts to clean its shoreline and banks, and to mitigate the introduction of contaminants from combined sewage and storm water outflows, as has been the goal and involvement of organizations such as the Bronx River Alliance, other local NGOs, New York City’s Department of Environmental Protection, New York State’s Department of Environmental Conservation and the Office of the Attorney General of the State of New York. So far these efforts have proven to be remarkably successful (Bode et al. 1999, Larson et al. 2004, Rachlin 2005). This success and the use of the river’s fish fauna as the object of a recreational fishery, especially for youngsters, provides the various communities along its banks with a sense of ownership, and argues well for this urban river’s continued improvement in terms of water quality and visual appearance. Acknowledgments The authors wish to thank CUNY graduate students Linda Lalicata and Athena Tiwari and undergraduate student Cindy Walsh from Lehman Col lege’s Laboratory for Marine and Estuarine Research, several un der grad u ate and grad u ate students from SUNY Maritime College, and SUNY Maritime College’s Cap tains 2007 J.W. Rachlin, B.E. Warkentine, and A. Pappantoniou 543 Fleureton, Johansson, Palmiotti, and Smith for their field assistance. 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