John Lyons, Wisconsin Department of Natural Resources
Publication Date - April 2011
|Common Name:||Pugnose Shiner|
|Other Common Names:||Pug-nosed shiner (Greene 1935)|
|Scientific name:||Notropis anogenus|
|Etymology:||Notropis - Greek, meaning back, keel|
anogenus - Greek, meaning without a chin
The pugnose shiner is a member of the minnow family, Cyprinidae, and was described by Forbes (1885) from the Fox River at McHenry, Illinois, about 18 km south of the Wisconsin border. Since then, little has been published on the systematics or taxonomy of this species, probably because of its scarcity. Bailey (1959) described the distribution and morphology of the pugnose shiner and suggested that it might be most closely related to the Topeka shiner (Notropis tristis [= topeka]), a species occurring in the Great Plains to the south and west of Wisconsin. He also noted the similarity in appearance between the pugnose shiner and two Wisconsin species, the blackchin shiner and the pugnose minnow. Other authors (Scott and Crossman 1973; Trautman 1981; Becker 1983; Smith 1985; Leslie and Timmins 2002) have commented on the resemblance of pugnose shiners to one or both of these species. In a comprehensive review of the systematics of North American Cyprinidae, Mayden (1989) placed the pugnose shiner in the weed shiner species group, a group of eight that includes the blackchin shiner but not the Topeka shiner or pugnose minnow. However, more recent classifications of North American minnows based on DNA sequences (but excluding pugnose shiner data) raise questions about the makeup and validity of the weed shiner species group and indicate that the relationship of the pugnose shiner to other minnows remains uncertain (Mayden et al. 2006).
Scientists from Canada are currently looking at genetic relationships among populations of the pugnose shiner across its range using microsatellite DNA (N. Mandrak, Canadian Department of Fisheries and Oceans, personal communication, 2010). Initial results suggest that all pugnose shiner populations derive from ancestors that survived the most recent ice age in a single refugium in an unglaciated portion of the Mississippi River basin. However, despite their common ancestry, current populations have developed distinctive genetic characteristics. Populations in Iowa and Minnesota are more similar to each other genetically than those from eastern Wisconsin, Michigan, and southern Ontario, which are in turn more similar to each other than those from New York and eastern Ontario.
The pugnose shiner body is slender, delicate, and slightly laterally compressed, with a body width of about 15% of standard length (SL) and a maximum body depth of 22-23% (all percentages from Smith 1985 and Leslie and Timmins 2002). The head is rounded and blunt in side view, averaging about 25-27% of SL. The mouth is small, 3% of SL, and superior, oriented nearly vertically relative to the long axis of the body.
No barbels are present on the head. The upper jaw reaches only to the anterior nostril. The eye is relatively large, 9-10% of SL. The pharyngeal teeth formula is 0,4-4,0, and the teeth are hooked and weakly serrated. There are six to eight short gill rakers on each side of the first gill arch (all counts from Bailey 1959; Scott and Crossman 1973; Becker 1964a, 1983; Smith 1985: Leslie and Timmins 2002). The single dorsal fin has eight or rarely nine rays and no spines. The anal fin typically has eight rays with a range of 7-10. The pelvic fins are abdominal and located slightly in advance of origin of dorsal fin, with eight rays each. The posterior tip of the pelvic fin extends to or beyond the anus in males but does not reach the anus in females (Becker 1983). Breeding males have minute tubercles on their heads and thickened and roughened pelvic and pectoral fin rays (Trautman 1981). The pectoral fins of pugnose shiners have 11-14 rays each. The lateral line is complete with 34-38 cycloid scales. There are four to five scale rows above the lateral line and three to four below (Smith 1985). The primary type specimen has 23 circumferential scale rows (none on the breast) and 12 around the caudal peduncle (Bailey 1959). Pugnose shiners have 32-36 vertebrae (Scott and Crossman 1973). The digestive tract is S-shaped and is about 60-70% of total length (TL) (Becker 1983). The peritoneum is dark brown to black over a silvery background (Bailey 1959; Becker 1983).
The overall background color of the pugnose shiner is silvery, with light tan, straw, or yellowish tints on the back and sides grading to whitish tints on the belly. The scales above the lateral line and on the back are outlined in dark pigment. A dark lateral stripe is present (inconspicuous in some live fish; most pronounced in preserved specimens) that is one to two scale rows wide with a jagged border that gives the stripe a slight "zig-zag" appearance.
The stripe extends from a small dark spot at the base of the tail forward through the eye and snout, ending on the posterior part of the upper jaw, prior to the lips. The upper chin also has dark pigment. Pre- and post-dorsal and post-anal stripes are faint or absent. All fins are unpigmented or slightly dusky. There are no distinctive colors on breeding fish, and juveniles appear similar to adults.
Among Wisconsin species, the pugnose shiner is most similar to the blackchin shiner, weed shiner, ironcolor shiner, and pugnose minnow. Table 1 gives characteristics useful for distinguishing these five shiners. Of the five, only the blackchin shiner has been found together in the same habitat with the pugnose shiner. I find live blackchin and pugnose shiners very difficult to tell
Table 1. Characteristics for distinguishing pugnose shiners from four other similar species.
|Characteristic||Pugnose shiner||Blackchin shiner||Weed shiner||Ironcolor shiner||Pugnose minnow|
|Pharnygeal tooth formula||0,4-4,0||0,4-4,0 or 1,4-4,1||2,4-4,2||2,4-4,2||0,5-5,0 or 0,5-4,0|
|Mouth orientation||Nearly vertical||Oblique||Oblique||Oblique||Nearly vertical|
|Color inside mouth||White||White||White||Black||White|
|Pigment on tip of chin||Dark||Dark||Dark||Dark||None|
|Peritoneum color||Black or dark brown||Silvery||Silvery||Silvery||Silvery|
|Number of dorsal rays||8, rarely 9||8||8||8||Usually 9|
|Males, dorsal fin pigment||None||None||None||None||Dark, clear middle|
|Number of anal rays||Usually 8, 7 common||8||7||8||8|
|Lateral stripe scales/margin||1-2 rows/zig-zag||1-2 rows/zig-zag||1-2 rows/zig-zag||2-3 rows/straight||1-2 rows/zig-zag|
|Light stripe on flank||Absent||Absent||Present||Present||Absent|
apart, and Smith (1985) stated that he could not distinguish them in the field. Bailey (1959) reported that among eight specimens used in the original description of pugnose shiner, two were actually blackchin shiners. More information on how to identify pugnose shiners can be found at http://www.seagrant.wisc.edu/home/Default.aspx?tabid=604.
The pugnose shiner is small and short-lived. The only published quantitative data on age and growth of this species are from Wisconsin (Becker 1983). The largest specimen known is a female of 60 mm total length (TL) and 2.4 g from Lower Nemahbin Lake, Waukesha County. Males may have a maximum size of only 50 mm TL. The oldest fish are three years old. Based on limited growth analyses from scales, pugnose shiners reach 22-32 mm TL at age 1, 30-43 mm at age 2, and 47-57 mm at age 3.
The pugnose shiner occurs infrequently over a fairly wide range that encompasses recently glaciated areas of the Great Lakes region.
The species is found throughout much of the Great Lakes basin across Wisconsin, Michigan, and small parts of Indiana, Ohio, New York, and southern Ontario (Bailey 1959; Gilbert 1980). Within the Great Lakes basin, pugnose shiners are least frequently encountered in the Lake Superior sub-basin, with only three confirmed localities, one in Delta Lake, Bayfield County (Fago 1992; UWZM 11958) and the other two in the upper St. Louis River drainage in Minnesota (Schmidt and Proulx 2009). Pugnose shiners also are known from the Mississippi River basin in Wisconsin, Minnesota, and northern Iowa, Illinois, and Indiana, and from the Hudson Bay basin (Red River of the North drainage) in western Minnesota and eastern North Dakota (Bailey 1959; Gilbert 1980; Koel and Peterka 2003).
The pugnose shiner is nowhere common and has declined in distribution and abundance over the last 100 years. Bailey (1959) considered it one of the rarest cyprinids in the northern United States and southern Canada. The pugnose shiner has been extirpated from North Dakota (Koel and Peterka 1998), Indiana (T. P. Simon, U.S. Fish and Wildlife Service, personal communication 2002), and Ohio (Trautman 1981). It is legally designated as endangered in New York (Carlson 1997) and Illinois (Herkert 1992) and as threatened in Iowa (Harlan et al. 1987) and Wisconsin (WDNR 1997), and it is considered rare, vulnerable, or of special concern in Minnesota (MDNR 1996), Michigan (Zorn and Sendek 2001), and Ontario (Parker et al. 1987). The American Fisheries Society and the American Society of Herpetologists and Ichthyologists consider the pugnose shiner threatened throughout its range (Jelks et al. 2008). The Committee on the Status of Endangered Wildlife in Canada has assessed the pugnose shiner as endangered in Canada (COSEWIC 2002) and population recovery goals have been formulated (Venturelli et al. 2010). Chu et al. (2005) predicted that the pugnose shiner might expand its distribution in southern Canada over the next 50 years as a result of global climate warming but that it would still remain uncommon.
In Wisconsin, the pugnose shiner is widespread but rare. It occurs at scattered localities throughout all areas of the state except the unglaciated Driftless Area in the southwest, where the natural lakes and low gradient streams it prefers are scarce (Becker 1983; Fago 1992).
I consider all reports of pugnose shiners from the Mississippi River (generally unpublished or in internal government memoranda) as erroneous and based on misidentified or mislabeled pugnose minnows, which are relatively common there. Strongholds of the pugnose shiner are in the lake districts of southeastern and northwestern Wisconsin.
More detail on the distribution of the pugnose shiner in Wisconsin can be found at http://infotrek.er.usgs.gov/wdnrfish/map/index.
Pugnose shiners are rightfully considered threatened in Wisconsin. They have disappeared from many state waters where they once occurred, including lakes and low gradient streams in the headwaters of the Fox River in central Wisconsin (Becker 1983), Lake Mendota, Dane County, and Pewaukee Lake, Waukesha County (Lyons 1989), and in Lake Ripley, Jefferson County (Lyons et al. 2000). Nowhere are they numerous, and most collections yield fewer than 10 individuals. However, their future is not quite as grim as once believed (Becker 1971). Extensive statewide sampling between 1974 and 1980 for the WDNR Fish Distribution Survey (Fago 1992) and subsequently during WDNR research studies up to the present (Lyons et al. 2000; WDNR unpublished data) revealed several new localities for the pugnose shiner. All told, I estimate that about 30 different waters in the state currently contain the species, compared with about 20 mapped in Becker (1983) But most of the newly discovered populations are small and localized, and I still consider it a special day when I encounter this species.
The pugnose shiner is a habitat specialist. It occurs only in the nearshore shallows of cool or warmwater lakes and low-gradient streams with clear water and extensive aquatic vegetation (Becker 1964a, 1964b, 1983; Trautman 1981; Carlson 1997; Leslie and Timmins 2002; Wei et al. 2004). It is sensitive to turbidity and losses of aquatic vegetation (Bailey 1959; Becker 1983; Schmidt and Proulx 2009). Bottom substrates where it is found are variable, including gravel, sand, mud, marl, organic debris, and clay (Becker 1964a, 1964b, 1983; Trautman 1981; Parker et al. 1987). The species is associated with a diverse assemblage of aquatic plants, including submerged and emergent macrophytes and filamentous green algae (Becker 1983).
In the Red River drainage of northwestern Minnesota, pugnose shiners were most frequently encountered in medium-sized streams with stable flows, clear water, and moderate conductivity (379-570 µS) (Koel and Peterka 2003). In central Minnesota lakes, pugnose shiner were found only where there was high water transparency (Secchi depths >1.8 m) and large, un-fragmented areas of common or abundant aquatic vegetation, particularly muskgrass (Chara species) (Schmidt and Proulx 2009).
Very little is known about the biology of the pugnose shiner. By far the best and most detailed information available is from Becker (1983) based largely on observations made by his son Dale from Lower Nemahbin Lake.
Pugnose shiners spawn in the spring and early summer, from late May into July in Wisconsin (Becker 1983). Spawning behavior has not been described, but the eggs are believed to be broadcast over firm substrates with no nest established or parental care provided (Leslie and Timmins 2002). Water temperatures during spawning range from 21.1°C to 28.9°C. In Lower Nemahbin Lake, mature females had from 530 to 1,275 eggs, constituting 7-17% of their body weight, but not all eggs were mature and probably not all were spawned. Fully mature eggs were yellow and 0.7-1.3 mm in diameter, and immature eggs were white and 0.2-0.6 mm in diameter. In the Black River in the northeastern Lower Peninsula of Michigan, pugnose shiners spawned in mid-July and averaged 600 eggs per female (Norden and Kronschabl 1985).
Post-larval and small juvenile pugnose shiners are described by Leslie and Timmins (2002) Pugnose shiner juveniles are fully developed and appear similar to adults by a length of about 20 mm TL.
What little information is available has been summarized by Becker (1983) Seasonal movement patterns have not been studied in detail, but pugnose shiners appear to leave the shallows when aquatic macrophytes begin to die back in late summer and probably spend the winter in deeper water. In the spring, pugnose shiners do not return to the shallows until the aquatic vegetation there is well developed. Prior to spawning, large aggregations of mature fish may form; Dale Becker and crew captured 610 in one seine haul on May 14, 1977, in Lower Nemahbin Lake. During the spawning period, pugnose shiners live in active schools of 15-35 fish in midwater, but after the breeding season these schools are reduced to 6-12 fish. Pugnose shiners schools are always closely associated with aquatic vegetation, into which they dart at the first sign of danger.
In most of the waters where they occur, pugnose shiners are uncommon and localized, and there is uncertainty about the long-term sustainability of many populations. A computer simulation of pugnose shiner population viability done for the Canadian government indicated that populations with a 5% chance per generation of suffering a catastrophic mortality event required a population size of at least 1,929 adults and at least 0.7 ha of suitable habitat in lakes or 0.2 ha in rivers to have a high likelihood of long-term persistence (Venturelli et al. 2010). If there was a 10% chance per generation of catastrophic mortality, the minimum population size jumped to at least 14,235 adults and the minimum amount of habitat to 5 ha in lakes and 1.5 ha in rivers.
An acute toxicology study indicated that the pugnose shiner was relatively sensitive to treated wastewater discharges disinfected with chlorine compounds (Ward and DeGraeve 1978). Of the 12 fish species tested, a mix of minnow, sunfish, and trout and salmon species, the pugnose shiner was the second most sensitive to chlorine and the fourth most sensitive to bromine chloride.
Tomasso and Murphy (1983) presented data on the effects of two pesticides, aldrin and heptachlor, on the fin regeneration capabilities of "pugnose shiners." However, it seems more likely that the species they actually worked with was the pugnose minnow. They stated that their "pugnose shiners" were "obtained from a local bait shop." Given that they did their study in Tennessee, well outside the range of the pugnose shiner, and that even within its range, the pugnose shiner is too rare and fragile to be encountered in a bait dealer's tanks, it seems almost certain that the species used was not the pugnose shiner. The pugnose minnow is the common Tennessee species most likely to be confused with the pugnose shiner.
Most of what is known about pugnose shiner feeding comes from Becker (1983). His limited field observations indicated that the species eats filamentous green algae and small crustaceans, particularly the cladoceran zooplankton Daphnia and Chydorus. In an aquarium, pugnose shiners preferred green algae such as Chara and Spirogyra to animal food and would only eat the latter after the plant material was nearly gone. A plant diet is consistent with the internal morphology of the pugnose shiner; herbivorous fish usually have a convoluted gut with a black peritoneum like the pugnose shiner. However, in the Black River, Michigan, Norden and Kronschabl (1985) found that the diet of pugnose shiners was 50% cladoceran zooplankton, 33% insect (Diptera) larvae, and only 3% algae and other plant material.
The small, upturned mouth of the pugnose shiner has led some scientists to speculate that it feeds mainly on very small, even microscopic, items on or near the surface (e.g., Scott and Crossman 1973). However, Becker's (1983) aquarium observations indicated that the pugnose shiner could easily consume items twice as long as the mouth and that most feeding took place in midwater.
The pugnose shiner typically occurs in diverse fish assemblages and has been captured with many other fish species. In Wisconsin, the species most commonly associated with the pugnose shiner is the blackchin shiner (Becker 1983). I have never encountered pugnose shiners without also finding blackchin shiners, although blackchin shiners occur at many sites where pugnose shiners are absent. Other common associates are blacknose shiner, bluntnose minnow, bluegill, and Iowa darter. Several of these species are also closely associated with pugnose shiners in Michigan, New York, and Minnesota (Norden and Kronschabl 1985; Carlson 1997; Koel and Peterka 2003).
The pugnose shiner is too poorly known for its ecological role in Wisconsin waters to be well understood. However, given its low numbers, it seems unlikely to be an important food item for carnivorous animals or to have a substantial influence on its algae and zooplankton food base. Scarcity, small size, and fragility also prevent the pugnose shiner from being a bait species for angling. The pugnose shiner's protected legal status as a threatened species precludes its use by aquarium hobbyists.
The primary importance of the pugnose shiner to the people of Wisconsin is as an indicator species. The pugnose shiner is highly susceptible to pollution, turbidity, habitat degradation, and shoreline habitat modifications, particularly reductions in the amount and quality of aquatic vegetation, and serves as a sentinel of the quality of the lakes and streams that it inhabits. The Wisconsin warmwater index of biotic integrity, a tool for assessing aquatic ecosystem health based on their fish assemblages, considers the pugnose shiner an intolerant species (Lyons 1992). The presence of a healthy pugnose shiner population indicates good environmental conditions, whereas the decline or loss of a population is a sign of a degrading ecosystem.